Escitalopram intermittent use and brain reactivity to aggressive stimuli in premenstrual dysphoric disorder

Escitalopram intermittent use and brain reactivity to aggressive stimuli in premenstrual dysphoric disorder | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Escitalopram intermittent use and brain reactivity to aggressive stimuli in premenstrual dysphoric disorder Manon Dubol, Maria Gröndal, Felix Schmidt, Patrick M Fisher, Vibe G Frokjaer, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6224514/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: Premenstrual dysphoric disorder (PMDD) is a depressive disorder linked to the menstrual cycle, notably characterized by the cyclic occurrence of emotional distress. A core symptom is irritability or anger, whose outcome can be aggressiveness. Intermittent selective serotonin reuptake inhibitor (SSRI) treatment has shown promise in alleviating symptoms, yet the neural underpinnings of its rapid efficacy remain unknown. This randomized controlled trial aimed to evaluate the impact of intermittent SSRI treatment for PMDD on aggression-related brain function. Methods: Women with PMDD (n = 62) were randomized to receive either intermittent escitalopram (20mg/day) or placebo during the luteal phase of the menstrual cycle. Symptoms were assessed using the Daily Record of Severity of Problems. Functional magnetic resonance imaging (fMRI) was conducted in combination with the Point Subtraction Aggression Paradigm (PSAP) to evaluate neural responses to aggression-related stimuli. Results: Intermittent escitalopram treatment significantly reduced PMDD symptoms compared to placebo, particularly irritability or anger. Aggressiveness, that was positively associated with these key symptoms, diminished as an effect of treatment, with irritability mediating the relationship between treatment and aggressiveness. Reactivity to provocations was associated with lower activation of the anterior insula upon treatment with escitalopram, which also positively related to irritability. Conclusions: These findings suggest a potential neural mechanism underlying the therapeutic effects of SSRIs in PMDD and provide insights into their role, in an interplay with gonadal hormones, in modulating reactive aggression. aggressiveness brain depression female functiona magnetic resonance imaging hormones premenstrual dysphoric disorder randomized controlled trial selective serotonin reuptake inhibitor Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Premenstrual dysphoric disorder (PMDD) is a depressive disorder characterized by recurring episodes of severe affective symptoms, including depression, irritability or anger, mood lability, and anxiety, which emerge in the days leading up to and around the onset of menstruation ( 1 , 2 ). The cyclical nature of symptom onset and resolution implicates the physiological fluctuations of gonadal hormones as a key factor in the pathogenesis of PMDD, as demonstrated by pharmacological interventions that impact such fluctuations ( 3 , 4 ). Among PMDD symptoms, irritability and anger are the most commonly reported and distressing ( 5 ), significantly impairing daily functioning and diminishing quality of life ( 6 ). It is well-established that premenstrual complaints, especially irritability, can be effectively reduced by treatment with selective serotonin reuptake inhibitors (SSRIs; Marjoribanks, Brown ( 7 )). Symptom relief occurs rapidly, often within hours to days upon starting SSRI medication, enabling effective intermittent treatment to be typically administered solely during the symptomatic phase, from ovulation to the onset of menstruation ( 8 , 9 ). The efficacy of SSRIs in alleviating mood-related premenstrual symptoms highlights the role of serotonergic transmission in their underlying mechanisms ( 10 ). Recent research indicates that women with PMDD experience altered serotonergic function during the premenstrual phase of the menstrual cycle ( 11 ). Additional support for serotonergic underpinnings of PMDD is that premenstrual mood symptoms can be triggered by tryptophan depletion, a precursor to serotonin ( 12 ), while serotonin receptor antagonists interfere with the symptom-relieving effects of SSRIs ( 13 ). Interestingly, while SSRIs might putatively rectify altered serotonergic properties in PMDD (Eriksson et al. 2006; Jovanovic et al. 2006; Marjoribanks et al. 2013)⁠, their rapid and efficacious action might in fact revert on neurotransmitter-steroid interactions. Notably, SSRIs are particularly effective in reducing premenstrual irritability, anger, and mood lability ( 14 , 15 ). This could indicate a reduced inhibitory effect of serotonin in PMDD-patients and aligns with a substantial body of research suggesting that serotonin plays a central physiological role in tempering sex steroid-driven behaviors, including various types of aggressive behaviors in many species, including humans ( 16 – 18 ). This highlights the importance of investigating whether SSRI treatment modulates aggression in PMDD-patients. Reactive aggressive behavior, while not explicitly listed in the diagnostic criteria for PMDD, aggravates in the premenstrual phase ( 19 , 20 ), as a response to elevated symptoms such as irritability and anger ( 21 ). Reactive aggression is typically defined as emotional and impulsive, as a response to threat, provocation, or frustration ( 22 , 23 ). In the present study, the monetary reward task, point subtraction aggression paradigm (PSAP; Skibsted, Cunha-Bang ( 24 )) was employed to investigate reactive aggression. Developed by Cherek ( 25 ), the PSAP offers an objective, free-operant measure of aggression by allowing participants to respond to provocation with aggressive behavior by stealing, and thereby reducing, the reward of the provoking opponent. Notably, this action does not increase the participant's monetary reward but solely serves to punish the opponent ( 26 ). Unlike paradigms that rely on competitive reaction-time tasks, the PSAP allows for continuous and voluntary responses, making it a more ecologically valid measure of real-world aggressive decision-making ( 27 ). Hence, the PSAP is an effective tool for investigating the behavioral mechanisms of reactive aggression. With its computerized format, the PSAP also offers a foundation for exploring the neural pathways underlying reactive aggression ( 24 , 28 – 30 ). The neural pathways associated with reactive aggression suggest altered connections between regions responsible for top-down control including the prefrontal cortex (PFC), orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and mesolimbic emotion-processing areas, such as the amygdala and insula, in aggressive individuals ( 31 , 32 ). Similar patterns are observed in nonclinical samples when playing PSAP, with a positive association between reactive aggressive behaviors and reactivity to provocations in brain areas related to emotion and cognitive top-down control such as the PFC, ACC, insula, and striatum ( 24 , 28 , 29 ). Additionally, one recent functional magnetic resonance imaging (fMRI) study using the PSAP highlighted an enhanced brain reactivity in the dorsal ACC and dorsomedial PFC of PMDD patients during aggressive responses, upon treatment that suppressed gonadal hormone fluctuations and associated with PMDD symptoms relief ( 3 , 33 ). The PSAP is sensitive to serotonin modulation, as evidenced by reduced aggressive responses during SSRI treatment ( 34 ) and increased aggression following serotonin depletion through tryptophan depletion ( 35 ). While studies on the neural effects of SSRIs in PMDD are limited, they hold great promise, especially given prior neuroimaging findings that suggest altered top-down regulation of subcortical reactivity in PMDD ( 36 ). The purpose of the present randomised, double-blind placebo-controlled neuroimaging study was to investigate the psychoneurobiological signatures of SSRI treatment in relation to reactive aggression in patients with PMDD. EU Clinical Trial Register (EudraCT) identifier: 2016-001217-25 URL: https://www.clinicaltrialsregister.eu/ctr-search/search?query=2016-001217-25 Trial registry name: Emotion, Serotonin and Premenstrual Dysphoric Disorder (EmSeP) Methods Participants The study was conducted at the Departments of Obstetrics and Gynecology at Uppsala University Hospital. Participants were recruited through advertisements in local newspapers and social media. A total of 131 women were assessed for eligibility, from which 62 were enrolled in the study. Eligible participants were women aged 18–46 years who had regular menstrual cycles, and met the DSM-5 criteria for PMDD ( 37 ). Exclusion criteria included ongoing mental health conditions assessed using the Mini International Neuropsychiatric Interview (MINI)( 38 ), ongoing drug or alcohol abuse, past hospitalization for psychiatric disorders, attempted suicide, or use of psychotropic medications within the past three months. Additionally, women with severe medical conditions such as liver disease, those treated with hormonal contraceptives or other steroid hormone therapies within the last three months, as well as pregnant, breastfeeding, or pregnancy-planning women, were excluded. Women with a history of depressive or anxiety disorders were allowed to participate, provided these conditions were no longer active. Past depressive episodes and panic disorders were assessed using the MINI, while past anxiety disorders and treatments were evaluated using structured questions in the case report form. Participants received both oral and written information about the study and had the opportunity to ask questions before providing informed consent in the presence of an investigator. All study procedures adhered to Good Clinical Practice and the ethical standards outlined in the Helsinki Declaration. The study was approved by the Regional Ethical Review Board in Uppsala (DNR 2016/312) and the Medical Products Agency in Sweden. The clinical trial ‘Emotion, Serotonin and Premenstrual Dysphoric Disorder’ (EmSeP) was registered under the EU Clinical Trial Register identifier EUDRA-CT 2016-001217-25. The CONSORT diagram of the trial is presented in Supplementary Fig. 1 and a flowchart for the neuroimaging sub-study is provided in Supplementary Fig. 2. PMDD diagnosis PMDD diagnosis was confirmed using the Daily Record of Severity of Problems (DRSP)( 39 ), which participants completed daily for at least two menstrual cycles via a smartphone application. The DRSP comprises 21 items representing 11 PMDD symptoms, including depression, anxiety, mood swings, irritability, decreased interest in activities, concentration difficulties, fatigue, sleep disturbances, increased appetite or cravings, feelings of being overwhelmed, and physical symptoms. Each item is rated on a 6-point Likert scale, from 1 (not at all) to 6 (extreme). Daily diary entries also included reports on menstrual bleeding. Following the DSM-5 criteria, PMDD was defined as a > 50% increase in at least five of the 11 symptoms from the follicular phase (days 6–12) to the luteal phase (days − 7 to − 1), with at least one being a core affective symptom (depression, anxiety, mood swings, irritability). Percent change was calculated as (mean luteal phase score − mean follicular phase score) / mean follicular phase score × 100. Diagnostic symptoms were required to be at least mild (mean luteal phase score > 3.0) and absent/minimal during the follicular phase (mean follicular phase score < 2.0). Women who did not meet PMDD criteria after two cycles of tracking were given the option to continue for an additional cycle. Study design The study was conducted as a double-blind randomized control trial with a 1:1 computerized random assignment of PMDD patients to either 20 mg/day escitalopram (SSRI) or placebo for up to 15 days during the luteal phase (Fig. 1 A). Indistinguishable escitalopram (Escitalopram®, Lundbeck, Sweden) and placebo tablets were packaged, labelled and listed with no information of allocation available for the local study personal and participants. Treatment drugs were assigned in ascending order. All participants attended an initial screening visit to ensure their eligibility and to gather anamnestic information and clinical data. Subsequently, subjects rated their symptoms with the DRSP for two diagnostic cycles to confirm the PMDD diagnosis. Eligible individuals were then invited for a baseline examination in the symptomatic luteal phase, timed based on their reporting of previous menstrual bleeding and average cycle length. During this session, venous blood samples were collected prior to psychometric testing, to analyse hormone levels. Upon completion of the baseline examination, subjects received their randomization code and tablets. They were instructed to start the treatment on day 14 of the ensuing menstrual cycle, while reporting daily their symptom ratings using the DRSP. The follow-up visit was scheduled analogously to the baseline session in the luteal phase of the treatment month. All participants were asked to bring the tablet packaging at the follow-up session for compliance control. Patient monitoring and contact was maintained in between sessions, ensuring prospective symptom charting during the trial without unmasking. During the follow-up visit, anatomical and functional brain scans were collected in addition to psychometric data and blood samples. Psychometric data included the self-rating Revised Swedish Version of the Aggression Questionnaire (AQ-RSV), to quantify aggression both before and after treatment ( 40 ). Treatment outcomes The primary treatment outcome measure was the change in premenstrual DRSP total score from baseline. The DRSP total score was calculated as the sum of the 21 items, each averaged over the last five days of the luteal phase at baseline and during the follow-up cycle. Secondary outcomes included changes from baseline in DRSP subscales based on the DSM-5 categorization of the four core PMDD symptoms, to evaluate symptom class-specific treatment effects. The DSM-5 symptom categories included ( i ) depression, ( ii ) anxiety, ( iii ) affective lability, and ( iv ) anger/irritability. These consist of the DRSP items ( i ) felt depressed , felt hopeless , felt worthless or guilty ; ( ii ) felt anxious ; ( iii ) had mood swings, was more sensitive or easily hurt ; and ( iv ) felt angry or irritable , had conflicts with others . These subscales were scored analogously to the total DRSP score. Primary and secondary clinical outcomes were evaluated as absolute scores and change in percentage from baseline to follow-up cycle. Treatment response was defined as at least 30% decrease in the DRSP total score from baseline to follow-up. A dichotomous clinical outcome status was defined as either no remission or remission, based on whether the participant still fit the DSM-5 diagnostic criteria for PMDD or not (at least five symptoms with mean luteal phase score > 3.0 on the DRSP scale, with a > 50% increase from the follicular to the luteal phase, including at least one core affective symptom). Hormone analysis Estradiol, progesterone, and testosterone levels were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS) at the Core Facility of Metabolomics, University of Bergen. For the analysis, 300 µL of blood serum was used. Proteins were precipitated using acetonitrile, and the resulting supernatant underwent liquid–liquid extraction with ethyl acetate–heptane, facilitated by a Hamilton STAR pipetting robot (Bonaduz, Switzerland). Steroids were separated on a C-18 column (50 x 2.1 mm, 1.7 µm particle size) using an Acquity UPLC system (Waters, Milford, MA, USA). Separation was achieved via gradient elution over 14 minutes with water and methanol containing ammonium hydroxide as mobile phases. The UPLC system was coupled to a Waters Xevo TQ-S tandem mass spectrometer equipped with an electrospray ionization source. Detection of steroids was performed in multiple reaction monitoring (MRM) mode, with negative ion mode used for estradiol and positive ion mode for progesterone and testosterone. Two product ions were monitored for each compound to ensure the absence of interferences. The lower limit of quantification was 3.6 pmol/L for estradiol, 0.21 nmol/L for progesterone, and 0.11 nmol/L for testosterone. Due to disruptions caused by the COVID-19 pandemic, a proportion of the hormonal data was not available for analysis (11% at baseline, 37% at follow-up). fMRI task description The Point Subtraction Aggression Paradigm (PSAP, Fig. 1 B) has been previously described in detail ( 26 ). Briefly, participants could choose from: Option 1, requiring 100 consecutive presses to earn 1 point; Option 2, requiring 10 consecutive presses to subtract (“steal”) 1 point from a virtual opponent (aggressive response), or Option 3, requiring 10 consecutive presses, to gain a brief protection period during which the participant's points could not be stolen (protective response). Game status, including total score, press counts, and selected options, was visible to the participants inside the scanner. Provocations, in the form of stolen points, occurred every 6–60 seconds if the participants did not select Option 2 or Option 3. Completing Option 2 or Option 3 initiated a maximum 60-second provocation-free period, though participants were only explicitly informed about the protective effect of Option 2. Participants were told that while they could not keep points stolen from the opponent, the opponent retained stolen points. Hence, Option 2 reflected aggressive behaviour without direct monetary gain. Participants were provided with oral instructions about the PSAP, prior to scanning. Inside the scanner, participants completed a one-minute practice trial before engaging in a 12-minute PSAP session. The paradigm was implemented using E-prime® v2.0 (Psychological Software Tools, Pittsburgh, PA). Behavioural outcomes included the total points earned, the number of provocations received, and the counts of presses for each option. Additionally, a PSAP aggression score was calculated as: (1000 x Number of Option 2) / (Total button presses x Number of provocations) ( 24 ). MRI acquisition, pre-processing, and analysis Structural and functional MRI was performed using a 3.0 Tesla whole-body MRI scanner (Achieva dStream, Philips Medical Systems, Best, The Netherlands) with a 32-channel head coil. A total of 240 dynamic whole-brain scans were collected using a T2*-weighted gradient echo-planar imaging (EPI) fMRI sequence with the following parameters: repetition time (TR) = 3000 ms, echo time (TE) = 30 ms, flip angle = 90°, matrix size = 100 x 97, 43 slices, slice thickness = 2.8 mm, and acquisition time = 12:11 min. The resulting images had a voxel size of 1.88 x 1.88 x 2.8 mm³. For anatomical reference, T1-weighted whole-brain scans were acquired using an MPRAGE sequence with the following parameters: TR = 8.3 ms, TE = 3.8 ms, flip angle = 8°, matrix size = 256 x 256, 220 slices, slice thickness = 1 mm, and acquisition time = 3:50 min. The resulting images had a voxel size of 0.94 x 0.94 x 1 mm³. fMRI data preprocessing and analysis steps were performed in Statistical Parametric Mapping (SPM12, Wellcome Centre for Human Neuroimaging, University College London, London, UK) implemented on Matlab, R2022b. The functional volumes were spatially realigned to the first image, unwarped, and corrected for slice timing before being co-registered with the anatomical scan, normalized into Montreal Neurological Institute space, and smoothed using a 4mm FWHM Gaussian filter. Outlier volumes were identified based on signal density (> 4) and motion (> 2 mm) using the Artifact Detection Tools ( http://www.nitrc.org/projects/artifact_detect ), and thereafter censored in the first-level fMRI analysis. First-level analysis of blood-oxygen-level-dependent (BOLD) signal change was performed by modelling the following conditions: Monetary Response (the first ten seconds of Option 1), Aggressive Response (duration of Option 2), Protective Response (duration of Option 3), Winning Reward (event, at end of Option 1), Stealing Reward (event, at end of Option 2) and Provocation (event, at time of provocation). The first 10 seconds of the Monetary Response (Option 1) were used as a baseline condition, as previously described in ( 24 ), to limit confounding effects from reward processing. If a provocation occurred during this period, the time from the beginning of Option1 until the provocation started was used. Single-subject design matrices, including these task conditions and the six head movement regressors obtained during spatial realignment, were estimated using general linear models to determine condition-specific BOLD responses, with the canonical HRF plus time-derivative. The following contrasts were computed: Provocation > Monetary Response, Aggressive Response > Monetary Response, Winning Reward > Monetary Response, Stealing Reward > Monetary Response, and Protective Response > Monetary Response. The generated single-subject contrast maps were then used for the second-level fMRI analysis to examine task-related brain reactivity over the whole group. Based on the previously described PSAP neural correlates ( 24 ), a region of interest (ROI) approach was employed. The ROIs were defined according to the AAL3 atlas, and included the left and right amygdala, striatum (putamen and caudate nuclei), ACC (subgenual, supgenual and pregenual areas), insula, and PFC (lateral and medial parts of the superior frontal gyrus, middle frontal gyrus, opercularis, triangularis and orbitalis parts of the inferior frontal gyrus). Statistical analyses Randomized Controlled Trial Using an intention-to-treat approach, the primary analyses were conducted using unblinded data from all participants with sufficient data. Differences between the two treatment groups in treatment response and remission status at the end of trial were assessed using χ 2 tests. To further evaluate the treatment effect on the overall symptom burden, we performed an analysis of variance with repeated measures of the DRSP total score. ‘Time’ was included as within-subject variable, with time points (baseline and follow-up) treated as repeated measures, and ‘Treatment’ (escitalopram or placebo) was entered as a fixed factor. An interaction term between treatment and time was included to assess the treatment effect. Similarly, we tested the Treatment x Time interaction effects on the DRSP subscales to further delineate the treatment effects across symptom dimensions. Multiple testing corrections were applied for the DRSP subscales using the False Discovery Rate (FDR)(four tests). Post-hoc independent-samples Mann-Whitney U Tests were run to assess the difference in DRSP scores at follow-up between treatment group, with effect sizes given as Cohen’s d. All analyses were performed using SPSS for Windows, version 28.0.1.0 (IBM, Armonk, NY), with a significance threshold set at p < 0.05. PSAP behaviour and aggression As many of the relevant behavioral variables in PSAP were not normally distributed (significant Shapiro-Wilk tests), independent t -tests with bootstrapped mean differences (bootstrap replicates = 1,000, using the boot package for R, version 4.4.2) were conducted to compare the groups in terms of behavioral outcomes (total points earned, number of provocations received, counts of presses for each option and aggression score). Changes in aggressiveness levels assessed with the total AQ-RSV score, in relation to escitalopram treatment, were investigated using an analysis of variance with repeated measures of the AQ-RSV total score. ‘Time’ was included as within-subject variable, with time points (baseline and follow-up) treated as repeated measures, and ‘Treatment’ (escitalopram or placebo) was entered as a fixed factor. An interaction term between treatment and time was included to assess the treatment effect. Post-hoc comparisons were carried out using one-sided two-sample and paired t-tests in SPSS for Windows, version 28.0.1.0 (IBM, Armonk, NY). A mediation analysis was conducted using the PROCESS macro for SPSS (Model 4, ( 41 )) to examine whether irritability levels (mediator) mediated the effect of treatment (independent variable) on aggressiveness (AQ-RSV score, dependent variable). Bootstrapped confidence intervals (5,000 resamples) were used to test the significance of the indirect effect, as this approach provides a more robust estimate by accounting for the non-normality of the sampling distribution of the mediation effect. Functional MRI The second-level fMRI analyses consisted in examining the task-related brain reactivity over the whole sample and delineating treatment group differences across the task conditions. One sample t-tests were run within masks of the predefined ROIs, to define brain reactivity to provocations, aggressive response, protective response, stealing points, and winning points. Condition-specific activations were visualized using a voxel-level significance threshold of p uncorrected < 0.001, with region-specific cluster extent thresholds of p FWE < 0.05 (Family-wise error correction). The extent thresholds were as follows: k ≥ 33 for PFC; k ≥ 12 for ACC; k ≥ 17 for the insulae; k ≥ 15 for the striatum; and k ≥ 4 for the amygdalae. To ensure that only task-responsive areas were assessed in terms of treatment group differences at follow-up, mean contrast estimates from statistically significant task-responsive clusters within ROIs were extracted. Differences in task-related brain activation across conditions were examined between treatment groups (escitalopram, placebo) using two-sample t-tests and Mann-Whitney U tests. FDR correction for multiple testing across the tested clusters’ data was applied. A mediation analysis was conducted using the PROCESS macro for SPSS (Model 4) to examine whether brain reactivity to the task conditions, within areas showing a significant treatment effect, mediated the relationship between treatment and irritability. Results - Participants’ characteristics In total, 62 women with PMDD participated in the study, and were randomized to either escitalopram (n = 33, SSRI group) or placebo (n = 29, placebo group). The CONSORT diagram of the randomized control trial is presented in Supplementary Fig. 1. Six participants discontinued the treatment (four in the SSRI group, two in the placebo group), resulting in a dropout rate of 11.3%. In the SSRI group, three participants stopped taking the treatment due to side effects, and one stopped due to personal reasons. Two of these participants continued to fill in the DRSP and were therefore included in the analysis, following an intention-to-treat approach. Likewise, one participant in the placebo group discontinued the treatment due to personal reasons but continued to fill in the DRSP, and was included in the analysis. Commonly reported side effects included nausea, headache, and dizziness. One participant reported a worsening of anxiety and depression, as well as concentration problems upon the first escitalopram intake. The demographic and clinical characteristics of the study sample are summarized in Supplementary Table 1. Overall, women included in the study were 34 ± 6 years old (mean ± standard deviation), had a healthy body mass index (24.6 ± 4.4), and had an average cycle length of 28.5 ± 2.5 days. Most participants were married or cohabiting, working part- or full-time, and had a high education level. Over a third had a history of depressive episodes, and about 16% had a history of anxiety. The self-reported duration of PMDD was 11 ± 7 years, on average. Over the whole sample, more than 75% had previously been treated for PMDD, primarily with antidepressants, and secondarily with hormonal and psychological treatments. Among those who had previously used antidepressants, 40% had terminated the treatment due to non-response, and 49% due to side effects. The two treatment groups did not differ in any of the demographic, hormonal, and clinical characteristics (Supplementary Table 1, Supplementary Fig. 2). - Escitalopram efficacy in PMDD Thirty-one women allocated to escitalopram treatment and twenty-seven women allocated to placebo treatment were included in the analysis of treatment effects. In each group, two participants failed to provide sufficient DRSP ratings during the RCT (dropped out of the study) and were excluded from the analysis. Participants in the SSRI group took escitalopram for an average of 10.4 ± 2.8 days (mean ± standard deviation), while participants in the placebo group took the treatment for 10.1 ± 2.9 days, on average. In both treatment groups, treatment duration did not relate to the extent of symptom change (Supplementary Fig. 3). Significant treatment-by-time effects on DRSP scores were detected, indicating differential patterns of symptom severity change over time in the two treatment groups. These effects included the total DRSP score (F = 6.24, p FDR =0.019), the DRSP depression score (F = 8.07, p FDR =0.015), the DRSP affective lability score (F = 6.64, p FDR =0.019), and the DRSP irritability score (F = 8.80, p FDR =0.015). At follow-up, significant group differences in these DRSP scores further indicated that escitalopram treatment was associated with a clear decrease in symptom severity compared to placebo (medium to large effect sizes, Supplementary Table 2). A graphical representation of the change in symptom severity from baseline to end of trial in each treatment group is given in Fig. 2 . The two groups did not differ in terms of remission at the end of the trial (SSRI: n = 23 non-remitters, n = 8 remitters; placebo: n = 22 non-remitters, n = 5 remitters; Χ 2 = 0.44, p = 0.51). However, a higher treatment response rate was observed in the SSRI group compared to placebo (SSRI: n = 15 responders, n = 6 non-responders; placebo: n = 6 responders, n = 21 non-responders; Χ 2 = 4.28, p = 0.04). - Task behaviour, aggressiveness, and brain reactivity The two groups performed the PSAP similarly, in terms of option choices, button presses, and the PSAP aggression score (Fig. 3 A, 3 B, Supplementary Table 3). Of note, the PSAP aggression score was not correlated with the AQ-RSV scores at follow-up with in any treatment group (Placebo: r = -0.15, p = 0.52; SSRI: ρ = -0.04, p = 0.87; Fig. 3 C). No significant group-by-time effect on AQ-RSV scores was found (F = 2.62, p = 0.11). However, the treatment groups displayed a significant difference in the total AQ-RSV score at follow-up (t = 1.87, p = 0.03, Cohen’s d = 0.55), and the escitalopram group displayed a significant decrease in AQ-RSV scores from baseline to follow-up (t=-2.07, p = 0.02, Cohen’s d=-0.42), while the scores remained stable in the placebo group (t=-.89, p = 0.19, Cohen’s d=-0.18) (Fig. 3 D). In order to test whether the effect of treatment on AQ-RSV scores could be mediated by the decrease in the severity of irritability, we evaluated associations between AQ-RSV scores and DRSP irritability scores before treatment. A positive association was observed between aggressiveness scores (AQ-RSV) and the severity of irritability (Fig. 3 E). At follow-up, the DRSP irritability scores remained positively associated with the AQ-RSV scores, while no significant correlation was observed between irritability and the PSAP aggression score (Fig. 3 F). A mediation analysis was then conducted to examine whether irritability levels mediated the effect of treatment on aggressiveness levels (Fig. 3 G). Treatment significantly predicted irritability and irritability significantly predicted aggressiveness, while the total effect of treatment on aggressiveness did not reach statistical significance (Fig. 3 G). Notably, the direct effect of treatment on aggressiveness, when controlling for irritability, was further reduced. The indirect effect of treatment on aggressiveness through irritability was statistically significant (95% CI [− 11.48, − 0.45]), indicating that irritability mediated the relationship between treatment and aggressiveness (Fig. 3 G). The partially standardized indirect effect was − 0.32 (95% CI [− 0.77, − 0.03]), suggesting a moderate effect size, and a significant mediation effect. In terms of neural correlates of the PSAP, provocations elicited significant brain activation within the PFC, ACC, amygdala, insula, and striatum across all participants (Fig. 4 ). During the aggressive response, sub-regions of the PFC, ACC, right insula and striatum showed significant activations (Fig. 4 ). Winning points during the task was associated with brain reactivity within the PFC, insula and striatum Fig. 4 ). Details about the precise location and magnitude of the main task effects on brain reactivity within ROIs are presented in Supplementary Table 4. We found no significant main effects of the PSAP ’Stealing’ and ’Protective response’ conditions in any ROI. - Effect of escitalopram on neural correlates of aggression Thirty-seven participants presented valid fMRI data at follow-up (SSRI group: n = 18; placebo group: n = 19; Supplementary Fig. 2). Among those, three chose the aggressive option of the PSAP less than two times, and were therefore excluded from the analyses involving this task condition (SSRI group: n = 2; placebo group: n = 1). A flowchart of the neuroimaging study sample is presented in Supplementary Fig. 4. Different reactivity to provocations was observed in the left anterior insula, with the BOLD signal being lower in the escitalopram group than in the placebo group (Fig. 5 A); however, this effect did not survive correction for multiple comparisons across the tested clusters (Supplementary Table S5). No significant correlation was found across all participants between the anterior insula reactivity to provocation and both the PSAP aggression score and the AQ-RSV score at follow-up (Supplementary Fig. 5). A positive association between activations in the anterior insula and the follow-up DRSP irritability scores was observed across all participants (ρ = 0.39, p = 0.016), suggesting that a greater engagement of this region in response to provocation relates to a higher degree of irritability (Fig. 5 B). Although bivariate analyses indicated an effect of treatment on insular reactivity to provocation, as well as an association between brain reactivity in this region and the severity of irritability, a mediation analysis did not support an indirect effect of treatment on irritability mediated by insular reactivity (coefficient = − 0.10, 95% CI [− 0.60, 0.52]). This suggests that while brain reactivity to provocation in the left anterior insula is related to both variables, it does not statistically account for the effect of treatment on irritability. Of note, no significant group differences in brain reactivity were observed during the aggressive response and winning reward task conditions (Supplementary Tables 6–7). Discussion The present pharmaco-neuroimaging study describes neural correlates of aggression in response to provocation in women with PMDD treated intermittently with escitalopram vs. placebo. The RCT demonstrates symptom domain-specific amelioration in PMDD symptoms by intermittently administered escitalopram. Dosage of 20 mg/day for up to fifteen luteal days led to a significant reduction in total DRSP scores, as well as scores of core mood symptoms such as anger and irritability, affect lability and depression, when compared to placebo. The findings confirm, in line with the literature, the strongest effects of SSRIs to be on anger and irritability, followed by affective lability and depression. Indeed, symptom-onset treatment has consistently been shown to primarily target mood-related symptoms—such as anger, irritability, and affective lability — rather than somatic symptoms, changes in appetite, or lack of energy ( 7 , 8 , 14 ). Moreover, as seen in SSRI treatment for depression, where certain symptoms (e.g., sleep disturbances and sexual dysfunction) may overlap with common medical side effects ( 42 ), the escitalopram group in the present study reported increased sleep disturbances and energy loss (see Fig. 2 ). This underscores the importance of evaluating SSRI treatment effect specifically on the symptoms they are intended to target—the core PMDD-symptoms. Intermittent escitalopram treatment led to a significant reduction in self-reported aggressiveness, as reflected in the decreased AQ-RSV scores observed exclusively in the group receiving escitalopram. Importantly, a positive association was observed between aggressiveness and irritability, both before and after treatment, reinforcing the link between these symptom dimensions in PMDD. However, no such relationship was found between irritability and PSAP aggression scores, suggesting that the PSAP may not fully capture the behavioral consequences of irritability in this population. A mediation analysis revealed that the reduction in aggressiveness following SSRI treatment was partly driven by improvements in irritability, with a statistically significant mediating effect. This finding highlights the role of irritability as a key mechanism through which SSRIs influence aggressiveness in PMDD. The moderate effect size further suggests that while serotonergic modulation effectively alleviates irritability, additional factors may contribute to the persistence of aggressive traits. Future studies should explore how individual differences in aggression regulation and interpersonal functioning influence treatment response, as well as investigate alternative behavioral measures that better capture the real-world impact of irritability and aggression in PMDD. Our functional neuroimaging findings align with previous research on the neural correlates of reactive aggression and provocation reactivity during the PSAP, implicating a network of regions involved in emotion processing and regulation ( 24 , 28 , 29 ). As expected, provocations elicited significant activation in key regions associated with aggression regulation, including the PFC, ACC, amygdala, insula, and striatum. Our findings suggest that intermittent escitalopram treatment can influence insular activity and this? is associated with reductions in affective PMDD symptoms, such as anger and irritability. Specifically, escitalopram appeared to dampen anterior insula reactivity to provocation, though this effect was relatively small. The anterior insula plays a well-established role in reactive aggression and processing negative emotional states triggered by provocation, which can lead to impulsive aggressive behavior ( 31 , 50 ). Prior research has also highlighted a modulatory role of serotonin in aggression-related neurocircuitry, including effects on insular activity ( 17 ). Additionally, neuroimaging studies suggest that the insula is involved in emotional processing in PMDD ( 36 ). Notably, PMDD patients have been showed to exhibit heightened insular reactivity to socially relevant stimuli during the luteal phase, compared to healthy controls ( 51 ). Since the PSAP includes a social component — where participants perceive provocation from a fictitious opponent — our findings may indicate that escitalopram modulates neural circuits involved in processing social cues in PMDD. Although our results must be interpreted with caution due to the exploratory nature of the study and the lack of statistical correction for multiple comparisons, they align with prior research suggesting that prosocial behaviors are linked to intact or enhanced serotonin function ( 52 , 53 ). Along the line of blunted top-down regulatory activation ( 54 ) and heightened emotional processing ( 55 ) in PMDD ( 36 ), the present findings of reduced insular activation upon treatment with escitalopram complement the ones showing higher fronto-cortical activation upon treatment with a selective progesterone receptor modulator ( 33 ). Interstingly, progesterone antagonism was associated with enhanced top-down control during aggressive responses — suggesting potential effects on cognitive regulation, which can be understood as complementary to the here observed decreased anterior insula reactivity to provocation, pointing to a downregulation of emotional processing. Importantly, the amygdala, ACC and PFC seem involved in PMDD pathophysiology ( 36 ) and are core components of the neural network underlying reactive aggression ( 31 ). Thus, our findings of reduced anterior insula involvement in response to provocations should be considered within the broader context of this network’s role in PMDD symptomatology. Notably, while anterior insula activation was significantly associated with irritability at follow-up, the mediation analysis did not support insular reactivity as an indirect pathway explaining treatment effects on irritability. This suggests that although the anterior insula is engaged in processing provocations and linked to irritability, its role in mediating the SSRI effects on aggression remains unclear. Furthermore, the lack of significant group differences in brain responses during aggressive behavior suggests that escitalopram’s effects may be specific to processing provocations, rather than the expression of aggressiveness itself. Future studies with larger samples and more targeted analyses are needed to further elucidate the mechanisms underlying SSRI effects on aggression-related neural circuitry. The present findings should be interpreted in light of methodological considerations. Treatment duration did not influence therapeutic response in this study (Supplementary Fig. 4). This is in line with the finding of rapid effect onset of SSRIs (Steinberg et al. 2012) and maximal efficacy gain of escitalopram within the first treatment cycle in PMDD (Eriksson et al. 2008a). It is indeed well established that SSRIs show selective action in PMDD, targeting specific symptom dimension ( 7 ), with intermittent treatment demonstrating an effect comparable to continuous treatment ( 43 ). The observed significant amelioration in irritability and anger upon treatment with escitalopram vs. placebo was not paralleled by behavioral differences in reactive aggression, as measured by the PSAP. Despite significant reductions in mood symptoms, previous studies using the PSAP have not observed behavioral changes in response to medical treatments for premenstrual dysphoria ( 20 , 33 ). A recent crossover study of patients with severe premenstrual irritability and anger found no behavioral differences in aggression during intermittent escitalopram treatment compared to placebo ( 20 ). Similarly, no differences in PSAP outcomes were observed in a RCT with selective progesterone receptor modulator (SPRM) treatment vs. placebo ( 33 ). The PSAP is an established test for assessing reactive aggression and has been widely used to examine how psychotropic drugs influence this behavior ( 34 , 44 ). A potential explanation for the lack of behavioral findings is that this laboratory task does not capture all aspects of reactive aggression but primarily measures punishment in response to provocation. This may miss to reflect the typical behavioral consequences of irritability and anger in PMDD, as the impairment mainly appears in home relationships, especially with one’s partner or children ( 45 ). Another potential explanation is that aggressive behavior tendencies differ between genders ( 46 , 47 ), with women more likely to employ indirect aggression ( 48 , 49 ), which is not specifically captured in the PSAP. Sex- and disorder-tailored tasks designed to focus on behavioral aspects of interpersonal interactions may therefore more accurately capture the impairments and consequences of PMDD symptoms, as, in addition to anger/irritability, interpersonal issues such as rejection sensitivity and conflicts are among the most prevalent and debilitating symptoms of PMDD ( 6 ). In summary, this pharmaco-neuroimaging study provides insights into the neural and behavioral effects of intermittent escitalopram treatment in women with PMDD. Escitalopram effectively alleviated core mood symptoms such as anger, irritability, and affective lability, though no significant behavioral changes in reactive aggression were detected using the PSAP. Neuroimaging findings revealed reduced activation in the left anterior insula during provocation in the escitalopram group, suggesting that serotonergic modulation may influence neural mechanisms underlying affective symptoms in PMDD. These results contribute to the growing evidence that SSRIs selectively target mood-related PMDD symptoms and highlight the need for more tailored behavioral paradigms to capture the interpersonal and context-dependent nature of aggression in PMDD. Declarations Acknowledgments We would like to thank Lena Moby and Sara Nyback for their help with data collection. We are additionally grateful to the Neuropsychopharmacology group for their valuable support. Conflict of interest The study drugs were supplied by Lundbeck, Sweden; however, the company had no further involvement in the study's design, data collection, analysis, interpretation of findings, or manuscript preparation. ISP has occasionally served on advisory boards or as an invited speaker at scientific meetings for Asarina Pharma, Bayer Health Care, Gedeon Richter, Peptonics, Shire/Takeda, Sandoz, and Lundbeck A/S. EE has been on advisory boards and/or received speaker's honoraria and/or research grants from H Lundbeck and Janssen. All other authors declare no conflicts of interest. Funding This study was funded by the Swedish Research Council (2015-00495, 2016-01439, 2020-01801, 2021-03089), the Swedish Society of Medicine (SLS-573171, SLS-597211, SLS-789101), and the Swedish Brain Foundation (2020-0255). Additionally, EC received funding from the Swedish Research EU FP7-People-Cofund (INCA 600398) and SciLifeLab. References Epperson CN, Steiner M, Hartlage SA, Eriksson E, Schmidt PJ, Jones I, et al. (2012): Premenstrual dysphoric disorder: evidence for a new category for DSM-5. Am J Psychiatry . 169:465-475. Hartlage SA, Freels S, Gotman N, Yonkers K (2012): Criteria for premenstrual dysphoric disorder: secondary analyses of relevant data sets. Arch Gen Psychiatry . 69:300-305. Comasco E, Kopp Kallner H, Bixo M, Hirschberg AL, Nyback S, de Grauw H, et al. (2021): Ulipristal Acetate for Treatment of Premenstrual Dysphoric Disorder: A Proof-of-Concept Randomized Controlled Trial. Am J Psychiatry . 178:256-265. Rubinow DR, Schmidt PJ (2019): Sex differences and the neurobiology of affective disorders. Neuropsychopharmacology . 44:111-128. Studer E, Nilsson S, Westman A, Pedersen NL, Eriksson E (2023): Significance and Interrelationship of the Symptoms Listed in the DSM Criteria for Premenstrual Dysphoric Disorder. Psychiatr Res Clin Pract . 5:105-113. Pearlstein TB, Bellew KM, Endicott J, Steiner M (2005): Paroxetine Controlled Release for Premenstrual Dysphoric Disorder: Remission Analysis Following a Randomized, Double-Blind, Placebo-Controlled Trial. Prim Care Companion J Clin Psychiatry . 7:53-60. Marjoribanks J, Brown J, O'Brien PM, Wyatt K (2013): Selective serotonin reuptake inhibitors for premenstrual syndrome. Cochrane Database Syst Rev .CD001396. Eriksson E, Ekman A, Sinclair S, Sorvik K, Ysander C, Mattson UB, et al. (2008): Escitalopram administered in the luteal phase exerts a marked and dose-dependent effect in premenstrual dysphoric disorder. J Clin Psychopharmacol . 28:195-202. Steinberg EM, Cardoso GM, Martinez PE, Rubinow DR, Schmidt PJ (2012): Rapid response to fluoxetine in women with premenstrual dysphoric disorder. Depress Anxiety . 29:531-540. Yonkers KA, O'Brien PM, Eriksson E (2008): Premenstrual syndrome. Lancet . 371:1200-1210. Sacher J, Zsido RG, Barth C, Zientek F, Rullmann M, Luthardt J, et al. (2023): Increase in Serotonin Transporter Binding in Patients With Premenstrual Dysphoric Disorder Across the Menstrual Cycle: A Case-Control Longitudinal Neuroreceptor Ligand Positron Emission Tomography Imaging Study. Biol Psychiatry . 93:1081-1088. Menkes DB, Coates DC, Fawcett JP (1994): Acute tryptophan depletion aggravates premenstrual syndrome. J Affect Disord . 32:37-44. Roca CA, Schmidt PJ, Smith MJ, Danaceau MA, Murphy DL, Rubinow DR (2002): Effects of metergoline on symptoms in women with premenstrual dysphoric disorder. Am J Psychiatry . 159:1876-1881. Eriksson E, Hedberg MA, Andersch B, Sundblad C (1995): The serotonin reuptake inhibitor paroxetin is superior to the noradrenaline reuptake inhibitor maprotiline in the treatment of premenstrual syndrome. Neuropsychopharmacology . 12:167-176. Landen M, Erlandsson H, Bengtsson F, Andersch B, Eriksson E (2009): Short onset of action of a serotonin reuptake inhibitor when used to reduce premenstrual irritability. Neuropsychopharmacology . 34:585-592. Takahashi A, Quadros IM, de Almeida RM, Miczek KA (2012): Behavioral and pharmacogenetics of aggressive behavior. Curr Top Behav Neurosci . 12:73-138. da Cunha-Bang S, Knudsen GM (2021): The Modulatory Role of Serotonin on Human Impulsive Aggression. Biol Psychiatry . 90:447-457. Bubak AN, Watt MJ, Yaeger JDW, Renner KJ, Swallow JG (2020): The stalk-eyed fly as a model for aggression - is there a conserved role for 5-HT between vertebrates and invertebrates? J Exp Biol . 223. Yen JY, Chen CC, Chang SJ, Ko CH, Chen CS, Yen CF (2011): Hostility, Impulsivity, and Behavior Inhibition Among Women with PMDD. CNS Spectr . 16:205-213. Grondal M, Naslund J, Englund C, Luke TJ, Ask K, Eriksson E, et al. (2025): Intermittent escitalopram treatment and reactive aggression in women with premenstrual irritability and anger: A crossover study. J Affect Disord . 369:599-607. Anderson CA, Bushman BJ (2002): Human aggression. Annu Rev Psychol . 53:27-51. Berkowitz L (1993): Aggression: Its Causes, Consequences, and Control . McGraw-Hill. Blair RJ (2016): The Neurobiology of Impulsive Aggression. J Child Adolesc Psychopharmacol . 26:4-9. Skibsted AP, Cunha-Bang SD, Carre JM, Hansen AE, Beliveau V, Knudsen GM, et al. (2017): Aggression-related brain function assessed with the Point Subtraction Aggression Paradigm in fMRI. Aggress Behav . 43:601-610. Cherek DR (1981): Effects of smoking different doses of nicotine on human aggressive behavior. Psychopharmacology (Berl) . 75:339-345. Geniole SN, MacDonell ET, McCormick CM (2017): The Point Subtraction Aggression Paradigm as a laboratory tool for investigating the neuroendocrinology of aggression and competition. Horm Behav . 92:103-116. Golomb BA, Cortez-Perez M, Jaworski BA, Mednick S, Dimsdale J (2007): Point subtraction aggression paradigm: validity of a brief schedule of use. Violence Vict . 22:95-103. Gan G, Preston-Campbell RN, Moeller SJ, Steinberg JL, Lane SD, Maloney T, et al. (2016): Reward vs. Retaliation-the Role of the Mesocorticolimbic Salience Network in Human Reactive Aggression. Front Behav Neurosci . 10:179. da Cunha-Bang S, Fisher PM, Hjordt LV, Perfalk E, Beliveau V, Holst K, et al. (2018): Men with high serotonin 1B receptor binding respond to provocations with heightened amygdala reactivity. Neuroimage . 166:79-85. Kose S, Steinberg JL, Moeller FG, Gowin JL, Zuniga E, Kamdar ZN, et al. (2015): Neural correlates of impulsive aggressive behavior in subjects with a history of alcohol dependence. Behav Neurosci . 129:183-196. Bertsch K, Florange J, Herpertz SC (2020): Understanding Brain Mechanisms of Reactive Aggression. Curr Psychiatry Rep . 22:81. Coccaro EF, McCloskey MS, Fitzgerald DA, Phan KL (2007): Amygdala and orbitofrontal reactivity to social threat in individuals with impulsive aggression. Biol Psychiatry . 62:168-178. Kaltsouni E, Fisher PM, Dubol M, Hustad S, Lanzenberger R, Frokjaer VG, et al. (2021): Brain reactivity during aggressive response in women with premenstrual dysphoric disorder treated with a selective progesterone receptor modulator. Neuropsychopharmacology . 46:1460-1467. Cherek DR, Lane SD, Pietras CJ, Steinberg JL (2002): Effects of chronic paroxetine administration on measures of aggressive and impulsive responses of adult males with a history of conduct disorder. Psychopharmacology (Berl) . 159:266-274. Marsh DM, Dougherty DM, Moeller FG, Swann AC, Spiga R (2002): Laboratory-measured aggressive behavior of women: acute tryptophan depletion and augmentation. Neuropsychopharmacology . 26:660-671. Dubol M, Neill Epperson C, Lanzenberger R, Sundstrom-Poromaa I, Comasco E (2020): Neuroimaging premenstrual dysphoric disorder: A systematic and critical review. Front Neuroendocrinol .100838. A.P.A. (2013): Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5) Sheehan DV, Lecrubier Y, Sheehan KH, Amorim P, Janavs J, Weiller E, et al. (1998): The Mini-International Neuropsychiatric Interview (M.I.N.I.): the development and validation of a structured diagnostic psychiatric interview for DSM-IV and ICD-10. J Clin Psychiatry . 59 Suppl 20:22-33;quiz 34-57. Endicott J, Nee J, Harrison W (2006): Daily Record of Severity of Problems (DRSP): reliability and validity. Arch Womens Ment Health . 9:41-49. Prochazka H, Agren H (2001): Aggression in the general Swedish population, measured with a new self-rating inventory: The Aggression Questionnaire--revised Swedish version (AQ-RSV). Nord J Psychiatry . 55:17-23. Hayes AF (2017): Introduction to mediation, moderation, and conditional process analysis: A regression-based approach . Guilford publications. Hieronymus F, Lisinski A, Eriksson E, Ostergaard SD (2021): Do side effects of antidepressants impact efficacy estimates based on the Hamilton Depression Rating Scale? A pooled patient-level analysis. Transl Psychiatry . 11:249. Landen M, Nissbrandt H, Allgulander C, Sorvik K, Ysander C, Eriksson E (2007): Placebo-controlled trial comparing intermittent and continuous paroxetine in premenstrual dysphoric disorder. Neuropsychopharmacology . 32:153-161. Moeller FG, Dougherty DM, Swann AC, Collins D, Davis CM, Cherek DR (1996): Tryptophan depletion and aggressive responding in healthy males. Psychopharmacology (Berl) . 126:97-103. Hylan TR, Sundell K, Judge R (1999): The impact of premenstrual symptomatology on functioning and treatment-seeking behavior: experience from the United States, United Kingdom, and France. J Womens Health Gend Based Med . 8:1043-1052. Hyde JS (2005): The gender similarities hypothesis. Am Psychol . 60:581-592. Denson TF, O'Dean SM, Blake KR, Beames JR (2018): Aggression in Women: Behavior, Brain and Hormones. Front Behav Neurosci . 12:81. Darko G, Bjorkqvist K, Osterman K (2019): Low intensity intimate partner aggression in Ghana: Support for the revised gender symmetry theory in an African country. Aggress Behav . 45:52-61. Potegal M, Archer J (2004): Sex differences in childhood anger and aggression. Child Adolesc Psychiatr Clin N Am . 13:513-528, vi-vii. Dambacher F, Sack AT, Lobbestael J, Arntz A, Brugman S, Schuhmann T (2015): Out of control: evidence for anterior insula involvement in motor impulsivity and reactive aggression. Soc Cogn Affect Neurosci . 10:508-516. Gingnell M, Ahlstedt V, Bannbers E, Wikstrom J, Sundstrom-Poromaa I, Fredrikson M (2014): Social stimulation and corticolimbic reactivity in premenstrual dysphoric disorder: a preliminary study. Biol Mood Anxiety Disord . 4:3. Miczek KA, de Almeida RM, Kravitz EA, Rissman EF, de Boer SF, Raine A (2007): Neurobiology of escalated aggression and violence. J Neurosci . 27:11803-11806. Crockett MJ, Clark L, Hauser MD, Robbins TW (2010): Serotonin selectively influences moral judgment and behavior through effects on harm aversion. Proc Natl Acad Sci U S A . 107:17433-17438. Comasco E, Hahn A, Ganger S, Gingnell M, Bannbers E, Oreland L, et al. (2014): Emotional fronto-cingulate cortex activation and brain derived neurotrophic factor polymorphism in premenstrual dysphoric disorder. Hum Brain Mapp . 35:4450-4458. Stiernman L, Dubol M, Comasco E, Sundstrom-Poromaa I, Boraxbekk CJ, Johansson M, et al. (2023): Emotion-induced brain activation across the menstrual cycle in individuals with premenstrual dysphoric disorder and associations to serum levels of progesterone-derived neurosteroids. Transl Psychiatry . 13:124. Additional Declarations The authors declare potential competing interests as follows: The study drugs were supplied by Lundbeck, Sweden; however, the company had no further involvement in the study's design, data collection, analysis, interpretation of findings, or manuscript preparation. ISP has occasionally served on advisory boards or as an invited speaker at scientific meetings for Asarina Pharma, Bayer Health Care, Gedeon Richter, Peptonics, Shire/Takeda, Sandoz, and Lundbeck A/S. EE has been on advisory boards and/or received speaker's honoraria and/or research grants from H Lundbeck and Janssen. V.G.F. has served as a consultant for SAGE therapeutics, and as a lecturer for H. Lundbeck, Janssen-Cilag and Gedeon-Richther. All other authors declare no conflicts of interest. Supplementary Files SUPPLEMENTpreprint.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6224514","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":428731773,"identity":"e0d0c700-1acb-4487-b708-48ddaeb56dd2","order_by":0,"name":"Manon Dubol","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Manon","middleName":"","lastName":"Dubol","suffix":""},{"id":428731774,"identity":"6d3798bb-28f9-4748-a5ce-30a2dd09d4dc","order_by":1,"name":"Maria Gröndal","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Maria","middleName":"","lastName":"Gröndal","suffix":""},{"id":428731775,"identity":"68489371-1975-4c3c-b913-7f06858cfe28","order_by":2,"name":"Felix Schmidt","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Felix","middleName":"","lastName":"Schmidt","suffix":""},{"id":428731776,"identity":"79ea3e61-70b9-44a2-834d-0527a9cf8366","order_by":3,"name":"Patrick M Fisher","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Patrick","middleName":"M","lastName":"Fisher","suffix":""},{"id":428731777,"identity":"4bcc78ab-ece1-48b8-bbc8-3401ea89d3d7","order_by":4,"name":"Vibe G Frokjaer","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Vibe","middleName":"G","lastName":"Frokjaer","suffix":""},{"id":428731778,"identity":"d8aa95cf-b0e5-4310-b35d-1c5c46c7984c","order_by":5,"name":"Elias Eriksson","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Elias","middleName":"","lastName":"Eriksson","suffix":""},{"id":428731779,"identity":"ed41bb9f-2a6d-4fdc-91f2-02d04483f31b","order_by":6,"name":"Inger Sundström Poromaa","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Inger","middleName":"Sundström","lastName":"Poromaa","suffix":""},{"id":428731780,"identity":"7b6edac2-437f-4bc2-8ee3-d6942e43b75c","order_by":7,"name":"Erika Comasco","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0UlEQVRIiWNgGAWjYFACxmYkTgXpWs4QZw0zkvY2ItTzSx9uNvjBYCen23784YeP8w4nNvAfPoBXi2RfYnNiD0OysdmZHGPJmduAWiTSEvBqMTjD2HyAh+FA4rYDOWzMvGAtPAZ4tdgDtRz8A9Jy/vkzZt45IIed/4DfFh7G5mSwLTcSzJh5G4BaGHLw6mCQANpiLGMA9MuNN8aSM46lG7dJpOF3GH8P+2PJNxV2cmbn0x9++FBjLdvPf/gBfmsgzkNisxGhfhSMglEwCkYBAQAAi15EPkyDDoAAAAAASUVORK5CYII=","orcid":"","institution":"","correspondingAuthor":true,"prefix":"","firstName":"Erika","middleName":"","lastName":"Comasco","suffix":""}],"badges":[],"createdAt":"2025-03-14 08:20:33","currentVersionCode":1,"declarations":{"humanSubjects":true,"vertebrateSubjects":false,"conflictsOfInterestStatement":true,"humanSubjectEthicalGuidelines":true,"humanSubjectConsent":true,"humanSubjectClinicalTrial":true,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-6224514/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6224514/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":78734293,"identity":"c63a4635-f7db-4134-8a3c-e57e0e1d183d","added_by":"auto","created_at":"2025-03-18 07:58:52","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":189417,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eStudy design. A. \u003c/strong\u003eThis pharmaco-functional MRI study\u003cstrong\u003e \u003c/strong\u003eincluded three visits (screening, randomization and follow-up visits). The timing of the three visits, in relation to a standardized menstrual cycle with schematic fluctuations of estradiol and progesterone is depicted. Upon the screening visit, participants’ eligibility was assessed through questionnaires such as the Mini International Neuropsychiatric Interview, and daily symptom rating was initiated using the Daily Record of Severity of Problems (DRSP). Following two menstrual cycles of DRSP ratings, PMDD diagnosis, as defined by the DSM-5, was confirmed. The randomization visit was planned in the symptomatic luteal phase and consisted in a baseline examination including psychometric testing, blood sampling, and the random assignment of PMDD patients to either 20 mg/day escitalopram or placebo, as part of a double-blind randomized control trial. Treatment duration was set to up to 15 days, starting mid-cycle. The follow-up visit was scheduled in the luteal phase of the treatment month, and consisted in a functional MRI scan using the Point Subtraction Aggression Paradigm (PSAP), psychometric testing, and blood sampling. \u003cstrong\u003eB. \u003c/strong\u003eThe PSAP was implemented using E-prime® and MR-compatible goggles and a 3-button response unit. Participants could choose from 3 options: “Earn”, “Steal” or “Protect”, requiring 100 consecutive presses to earn 1 point, or 10 consecutive presses to either subtract (“steal”) 1 point from a virtual opponent (aggressive response), or gain a brief protection period during which the participant's points could not be stolen (protective response). Game status, including total score, press counts, and the selected option, was visible to the participants inside the scanner. Provocations, in the form of stolen points, were depicted as a reduction of the total score by 1 point, surrounded by red minus signs. Participants completed a one-minute practice trial before engaging in a 12-minute PSAP block.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6224514/v1/ca68b579698419cd634a3a2b.png"},{"id":78734295,"identity":"f57bc2ae-0d85-4226-97e3-b48b91762c4c","added_by":"auto","created_at":"2025-03-18 07:58:52","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":89288,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eChange in symptom severity from baseline in patients with PMDD treated with Escitalopram, compared to placebo. \u003c/strong\u003eThe bar graph illustrates the percent change in premenstrual DRSP scores, averaged within the two treatment groups, for the total DRSP score and the DRSP scores corresponding to the eleven symptoms included in the DSM-5 criteria for PMDD. The DRSP total score was calculated as the sum of the 21 single items, each averaged over the last five days of the luteal phase at baseline and during the follow-up cycle. DRSP, Daily Record of Severity of Problems.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6224514/v1/e5b13e6d7a5fddaca2ccb87e.png"},{"id":78734298,"identity":"e85dce03-dca9-4bb8-8aee-59c4ce939cae","added_by":"auto","created_at":"2025-03-18 07:58:52","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":245742,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePSAP behaviour. \u0026nbsp;A. \u003c/strong\u003eThe task behaviour in terms of button presses (upper panel) and frequency of option choice (lower panel) is shown for each treatment group.\u003cstrong\u003e \u003c/strong\u003eThe bars and dots illustrate the data range and the median values, respectively. The pie charts illustrate the percentages of the choices in each group. \u003cstrong\u003eB. \u003c/strong\u003eThe average PSAP aggression scores (ratio of aggressive responses over provocations, adjusted for the total number of button presses) are shown for the two treatment groups. The bars and dots illustrate the data range and the median values, respectively. \u0026nbsp;\u003cstrong\u003eC. \u003c/strong\u003eThe scatterplot depicts the lack of association between the PSAP aggression score and the total score of the AQ-RSV (aggression score) at follow-up. The trend lines for each treatment groups are shown.\u003cstrong\u003e D. \u003c/strong\u003eThe line graph illustrates the change in the total AQ-RSV score from baseline to follow-up, in the two treatment groups. Participants treated with escitalopram showed a significant decrease in aggression, while the placebo group didn’t display any significant change.\u003cstrong\u003e E. \u003c/strong\u003eThe positive correlation between the total AQ-RSV score and the DRSP irritability score across all participant before treatment, is illustrated in the scatterplot\u003cstrong\u003e F. \u003c/strong\u003eThe heatmap of the correlation matrix between the PSAP aggression score, the total AQ-RSV score at follow-up, and the DRSP irritability score at follow-up shows a significant positive association between the AQ-RSV aggression score and the severity of irritability, across all participants.\u003cstrong\u003e G. \u003c/strong\u003eThe results of a mediation model\u003cstrong\u003e \u003c/strong\u003eindicate that the effect of escitalopram \u003cem\u003eversus\u003c/em\u003eplacebo on aggression scores obtained from the AQ-RSV is mediated by the change in irritability levels assessed by the DRSP. Abbreviations: AQ-RSV, Aggression questionnaires – revised Swedish version; DRSP, Daily Record of Severity of Problems; PSAP, Point Subtraction Aggression Paradigm.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-6224514/v1/e109ac8b4eb0110e261fd086.png"},{"id":78734303,"identity":"bf9fc299-0b2a-44ce-b303-77b79b100a38","added_by":"auto","created_at":"2025-03-18 07:58:52","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":942976,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eBrain reactivity during the PSAP, within regions of interest across all participants. \u003c/strong\u003eThe Main effect of task conditions on brain activations was assessed within ROIs, across treatment groups. The thresholded SPM T-maps from the individual voxel-wise ROI one-sample t tests analyses (height threshold: \u003cem\u003ep\u003c/em\u003e\u003csub\u003e\u003cem\u003euncorrected\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e \u003c/em\u003e\u0026lt; 0.001, extent threshold: p\u003csub\u003eFWE \u003c/sub\u003e\u0026lt; 0.05) are overlaid onto a standard MRI template and grouped per PSAP condition. The significant clusters are shown over coronal brain slices. No significant brain reactivity was seen in association to the ‘stealing’ and ‘protecting’ task conditions. No significant deactivations were found in relation to the task conditions. The thresholded T-maps were exported from SPM12 and brain figures were generated using MRIcroGL (v1.2.20220720).\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-6224514/v1/98a76969defb41a95174b1f9.png"},{"id":78734981,"identity":"389b42ab-d221-4670-8787-aef42fe377a0","added_by":"auto","created_at":"2025-03-18 08:06:52","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":179940,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eEffect of escitalopram on the PSAP neural correlates. A.\u003c/strong\u003e Raincloud plot depicting the differential reactivity to provocation within the left anterior insula in the two treatment groups (left panel). The left insula cluster showing a group difference is illustrated on coronal, axial and sagittal brain slices (right panel, x=-32, y=18, z=-4). The binary cluster image was exported from SPM12 and overlaid onto a standard MNI template in MRIcroGL (v1.2.20220720). \u003cstrong\u003eB.\u003c/strong\u003e Scatterplot showing a positive relationship between brain reactivity to provocation within the left anterior insula and the follow-up DRSP irritability scores, across the two treatment groups (black fit line). For completeness, the green and purple sub-group fit lines are also displayed.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-6224514/v1/0ccc33ccae173653888df251.png"},{"id":78737168,"identity":"a8a75268-4adb-4d87-8f51-0f2753c584f0","added_by":"auto","created_at":"2025-03-18 08:30:53","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2640602,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6224514/v1/eec1d73a-f8fb-43c3-80cb-92c116f0cdd9.pdf"},{"id":78734980,"identity":"7b7dc06b-04a2-4b45-b7b1-abafa6011425","added_by":"auto","created_at":"2025-03-18 08:06:52","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1562320,"visible":true,"origin":"","legend":"","description":"","filename":"SUPPLEMENTpreprint.docx","url":"https://assets-eu.researchsquare.com/files/rs-6224514/v1/e4e68d472d62c77e669e95e3.docx"}],"financialInterests":"The authors declare potential competing interests as follows: The study drugs were supplied by Lundbeck, Sweden; however, the company had no further involvement in the study's design, data collection, analysis, interpretation of findings, or manuscript preparation. ISP has occasionally served on advisory boards or as an invited speaker at scientific meetings for Asarina Pharma, Bayer Health Care, Gedeon Richter, Peptonics, Shire/Takeda, Sandoz, and Lundbeck A/S. EE has been on advisory boards and/or received speaker's honoraria and/or research grants from H Lundbeck and Janssen. V.G.F. has served as a consultant for SAGE therapeutics, and as a lecturer for H. Lundbeck, Janssen-Cilag and Gedeon-Richther. All other authors declare no conflicts of interest.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eEscitalopram intermittent use and brain reactivity to aggressive stimuli in premenstrual dysphoric disorder\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePremenstrual dysphoric disorder (PMDD) is a depressive disorder characterized by recurring episodes of severe affective symptoms, including depression, irritability or anger, mood lability, and anxiety, which emerge in the days leading up to and around the onset of menstruation (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). The cyclical nature of symptom onset and resolution implicates the physiological fluctuations of gonadal hormones as a key factor in the pathogenesis of PMDD, as demonstrated by pharmacological interventions that impact such fluctuations (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). Among PMDD symptoms, irritability and anger are the most commonly reported and distressing (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e), significantly impairing daily functioning and diminishing quality of life (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIt is well-established that premenstrual complaints, especially irritability, can be effectively reduced by treatment with selective serotonin reuptake inhibitors (SSRIs; Marjoribanks, Brown (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e)). Symptom relief occurs rapidly, often within hours to days upon starting SSRI medication, enabling effective intermittent treatment to be typically administered solely during the symptomatic phase, from ovulation to the onset of menstruation (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). The efficacy of SSRIs in alleviating mood-related premenstrual symptoms highlights the role of serotonergic transmission in their underlying mechanisms (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). Recent research indicates that women with PMDD experience altered serotonergic function during the premenstrual phase of the menstrual cycle (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). Additional support for serotonergic underpinnings of PMDD is that premenstrual mood symptoms can be triggered by tryptophan depletion, a precursor to serotonin (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e), while serotonin receptor antagonists interfere with the symptom-relieving effects of SSRIs (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). Interestingly, while SSRIs might putatively rectify altered serotonergic properties in PMDD (Eriksson et al. 2006; Jovanovic et al. 2006; Marjoribanks et al. 2013)⁠, their rapid and efficacious action might in fact revert on neurotransmitter-steroid interactions.\u003c/p\u003e \u003cp\u003eNotably, SSRIs are particularly effective in reducing premenstrual irritability, anger, and mood lability (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). This could indicate a reduced inhibitory effect of serotonin in PMDD-patients and aligns with a substantial body of research suggesting that serotonin plays a central physiological role in tempering sex steroid-driven behaviors, including various types of aggressive behaviors in many species, including humans (\u003cspan additionalcitationids=\"CR17\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e). This highlights the importance of investigating whether SSRI treatment modulates aggression in PMDD-patients.\u003c/p\u003e \u003cp\u003eReactive aggressive behavior, while not explicitly listed in the diagnostic criteria for PMDD, aggravates in the premenstrual phase (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e), as a response to elevated symptoms such as irritability and anger (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). Reactive aggression is typically defined as emotional and impulsive, as a response to threat, provocation, or frustration (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). In the present study, the monetary reward task, point subtraction aggression paradigm (PSAP; Skibsted, Cunha-Bang (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e)) was employed to investigate reactive aggression. Developed by Cherek (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e), the PSAP offers an objective, free-operant measure of aggression by allowing participants to respond to provocation with aggressive behavior by stealing, and thereby reducing, the reward of the provoking opponent. Notably, this action does not increase the participant's monetary reward but solely serves to punish the opponent (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e). Unlike paradigms that rely on competitive reaction-time tasks, the PSAP allows for continuous and voluntary responses, making it a more ecologically valid measure of real-world aggressive decision-making (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). Hence, the PSAP is an effective tool for investigating the behavioral mechanisms of reactive aggression. With its computerized format, the PSAP also offers a foundation for exploring the neural pathways underlying reactive aggression (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan additionalcitationids=\"CR29\" citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe neural pathways associated with reactive aggression suggest altered connections between regions responsible for top-down control including the prefrontal cortex (PFC), orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and mesolimbic emotion-processing areas, such as the amygdala and insula, in aggressive individuals (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e). Similar patterns are observed in nonclinical samples when playing PSAP, with a positive association between reactive aggressive behaviors and reactivity to provocations in brain areas related to emotion and cognitive top-down control such as the PFC, ACC, insula, and striatum (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e). Additionally, one recent functional magnetic resonance imaging (fMRI) study using the PSAP highlighted an enhanced brain reactivity in the dorsal ACC and dorsomedial PFC of PMDD patients during aggressive responses, upon treatment that suppressed gonadal hormone fluctuations and associated with PMDD symptoms relief (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe PSAP is sensitive to serotonin modulation, as evidenced by reduced aggressive responses during SSRI treatment (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e) and increased aggression following serotonin depletion through tryptophan depletion (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e). While studies on the neural effects of SSRIs in PMDD are limited, they hold great promise, especially given prior neuroimaging findings that suggest altered top-down regulation of subcortical reactivity in PMDD (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e). The purpose of the present randomised, double-blind placebo-controlled neuroimaging study was to investigate the psychoneurobiological signatures of SSRI treatment in relation to reactive aggression in patients with PMDD.\u003c/p\u003e \u003cp\u003eEU Clinical Trial Register (EudraCT) identifier: 2016-001217-25\u003c/p\u003e \u003cp\u003eURL: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.clinicaltrialsregister.eu/ctr-search/search?query=2016-001217-25\u003c/span\u003e\u003cspan address=\"https://www.clinicaltrialsregister.eu/ctr-search/search?query=2016-001217-25\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003eTrial registry name: Emotion, Serotonin and Premenstrual Dysphoric Disorder (EmSeP)\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eParticipants\u003c/h2\u003e \u003cp\u003eThe study was conducted at the Departments of Obstetrics and Gynecology at Uppsala University Hospital. Participants were recruited through advertisements in local newspapers and social media. A total of 131 women were assessed for eligibility, from which 62 were enrolled in the study. Eligible participants were women aged 18\u0026ndash;46 years who had regular menstrual cycles, and met the DSM-5 criteria for PMDD (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e). Exclusion criteria included ongoing mental health conditions assessed using the Mini International Neuropsychiatric Interview (MINI)(\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e), ongoing drug or alcohol abuse, past hospitalization for psychiatric disorders, attempted suicide, or use of psychotropic medications within the past three months. Additionally, women with severe medical conditions such as liver disease, those treated with hormonal contraceptives or other steroid hormone therapies within the last three months, as well as pregnant, breastfeeding, or pregnancy-planning women, were excluded. Women with a history of depressive or anxiety disorders were allowed to participate, provided these conditions were no longer active. Past depressive episodes and panic disorders were assessed using the MINI, while past anxiety disorders and treatments were evaluated using structured questions in the case report form.\u003c/p\u003e \u003cp\u003e Participants received both oral and written information about the study and had the opportunity to ask questions before providing informed consent in the presence of an investigator. All study procedures adhered to Good Clinical Practice and the ethical standards outlined in the Helsinki Declaration. The study was approved by the Regional Ethical Review Board in Uppsala (DNR 2016/312) and the Medical Products Agency in Sweden. The clinical trial \u0026lsquo;Emotion, Serotonin and Premenstrual Dysphoric Disorder\u0026rsquo; (EmSeP) was registered under the EU Clinical Trial Register identifier EUDRA-CT 2016-001217-25. The CONSORT diagram of the trial is presented in Supplementary Fig.\u0026nbsp;1 and a flowchart for the neuroimaging sub-study is provided in Supplementary Fig.\u0026nbsp;2.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003ePMDD diagnosis\u003c/h3\u003e\n\u003cp\u003ePMDD diagnosis was confirmed using the Daily Record of Severity of Problems (DRSP)(\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e), which participants completed daily for at least two menstrual cycles via a smartphone application. The DRSP comprises 21 items representing 11 PMDD symptoms, including depression, anxiety, mood swings, irritability, decreased interest in activities, concentration difficulties, fatigue, sleep disturbances, increased appetite or cravings, feelings of being overwhelmed, and physical symptoms. Each item is rated on a 6-point Likert scale, from 1 (not at all) to 6 (extreme). Daily diary entries also included reports on menstrual bleeding. Following the DSM-5 criteria, PMDD was defined as a\u0026thinsp;\u0026gt;\u0026thinsp;50% increase in at least five of the 11 symptoms from the follicular phase (days 6\u0026ndash;12) to the luteal phase (days \u0026minus;\u0026thinsp;7 to \u0026minus;\u0026thinsp;1), with at least one being a core affective symptom (depression, anxiety, mood swings, irritability). Percent change was calculated as (mean luteal phase score\u0026thinsp;\u0026minus;\u0026thinsp;mean follicular phase score) / mean follicular phase score \u0026times; 100. Diagnostic symptoms were required to be at least mild (mean luteal phase score\u0026thinsp;\u0026gt;\u0026thinsp;3.0) and absent/minimal during the follicular phase (mean follicular phase score\u0026thinsp;\u0026lt;\u0026thinsp;2.0). Women who did not meet PMDD criteria after two cycles of tracking were given the option to continue for an additional cycle.\u003c/p\u003e\n\u003ch3\u003eStudy design\u003c/h3\u003e\n\u003cp\u003eThe study was conducted as a double-blind randomized control trial with a 1:1 computerized random assignment of PMDD patients to either 20 mg/day escitalopram (SSRI) or placebo for up to 15 days during the luteal phase (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA). Indistinguishable escitalopram (Escitalopram\u0026reg;, Lundbeck, Sweden) and placebo tablets were packaged, labelled and listed with no information of allocation available for the local study personal and participants. Treatment drugs were assigned in ascending order.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAll participants attended an initial screening visit to ensure their eligibility and to gather anamnestic information and clinical data. Subsequently, subjects rated their symptoms with the DRSP for two diagnostic cycles to confirm the PMDD diagnosis. Eligible individuals were then invited for a baseline examination in the symptomatic luteal phase, timed based on their reporting of previous menstrual bleeding and average cycle length. During this session, venous blood samples were collected prior to psychometric testing, to analyse hormone levels. Upon completion of the baseline examination, subjects received their randomization code and tablets. They were instructed to start the treatment on day 14 of the ensuing menstrual cycle, while reporting daily their symptom ratings using the DRSP. The follow-up visit was scheduled analogously to the baseline session in the luteal phase of the treatment month. All participants were asked to bring the tablet packaging at the follow-up session for compliance control. Patient monitoring and contact was maintained in between sessions, ensuring prospective symptom charting during the trial without unmasking. During the follow-up visit, anatomical and functional brain scans were collected in addition to psychometric data and blood samples. Psychometric data included the self-rating Revised Swedish Version of the Aggression Questionnaire (AQ-RSV), to quantify aggression both before and after treatment (\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eTreatment outcomes\u003c/h3\u003e\n\u003cp\u003eThe primary treatment outcome measure was the change in premenstrual DRSP total score from baseline. The DRSP total score was calculated as the sum of the 21 items, each averaged over the last five days of the luteal phase at baseline and during the follow-up cycle. Secondary outcomes included changes from baseline in DRSP subscales based on the DSM-5 categorization of the four core PMDD symptoms, to evaluate symptom class-specific treatment effects. The DSM-5 symptom categories included (\u003cem\u003ei\u003c/em\u003e) depression, (\u003cem\u003eii\u003c/em\u003e) anxiety, (\u003cem\u003eiii\u003c/em\u003e) affective lability, and (\u003cem\u003eiv\u003c/em\u003e) anger/irritability. These consist of the DRSP items (\u003cem\u003ei\u003c/em\u003e) \u003cem\u003efelt depressed\u003c/em\u003e, \u003cem\u003efelt hopeless\u003c/em\u003e, \u003cem\u003efelt worthless or guilty\u003c/em\u003e; (\u003cem\u003eii\u003c/em\u003e) \u003cem\u003efelt anxious\u003c/em\u003e; (\u003cem\u003eiii\u003c/em\u003e) \u003cem\u003ehad mood swings, was more sensitive or easily hurt\u003c/em\u003e; and (\u003cem\u003eiv\u003c/em\u003e) \u003cem\u003efelt angry or irritable\u003c/em\u003e, \u003cem\u003ehad conflicts with others\u003c/em\u003e. These subscales were scored analogously to the total DRSP score. Primary and secondary clinical outcomes were evaluated as absolute scores and change in percentage from baseline to follow-up cycle. Treatment response was defined as at least 30% decrease in the DRSP total score from baseline to follow-up. A dichotomous clinical outcome status was defined as either no remission or remission, based on whether the participant still fit the DSM-5 diagnostic criteria for PMDD or not (at least five symptoms with mean luteal phase score\u0026thinsp;\u0026gt;\u0026thinsp;3.0 on the DRSP scale, with a\u0026thinsp;\u0026gt;\u0026thinsp;50% increase from the follicular to the luteal phase, including at least one core affective symptom).\u003c/p\u003e\n\u003ch3\u003eHormone analysis\u003c/h3\u003e\n\u003cp\u003eEstradiol, progesterone, and testosterone levels were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS) at the Core Facility of Metabolomics, University of Bergen. For the analysis, 300 \u0026micro;L of blood serum was used. Proteins were precipitated using acetonitrile, and the resulting supernatant underwent liquid\u0026ndash;liquid extraction with ethyl acetate\u0026ndash;heptane, facilitated by a Hamilton STAR pipetting robot (Bonaduz, Switzerland). Steroids were separated on a C-18 column (50 x 2.1 mm, 1.7 \u0026micro;m particle size) using an Acquity UPLC system (Waters, Milford, MA, USA). Separation was achieved via gradient elution over 14 minutes with water and methanol containing ammonium hydroxide as mobile phases. The UPLC system was coupled to a Waters Xevo TQ-S tandem mass spectrometer equipped with an electrospray ionization source. Detection of steroids was performed in multiple reaction monitoring (MRM) mode, with negative ion mode used for estradiol and positive ion mode for progesterone and testosterone. Two product ions were monitored for each compound to ensure the absence of interferences. The lower limit of quantification was 3.6 pmol/L for estradiol, 0.21 nmol/L for progesterone, and 0.11 nmol/L for testosterone. Due to disruptions caused by the COVID-19 pandemic, a proportion of the hormonal data was not available for analysis (11% at baseline, 37% at follow-up).\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003efMRI task description\u003c/h2\u003e \u003cp\u003eThe Point Subtraction Aggression Paradigm (PSAP, Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB) has been previously described in detail (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e). Briefly, participants could choose from: Option 1, requiring 100 consecutive presses to earn 1 point; Option 2, requiring 10 consecutive presses to subtract (\u0026ldquo;steal\u0026rdquo;) 1 point from a virtual opponent (aggressive response), or Option 3, requiring 10 consecutive presses, to gain a brief protection period during which the participant's points could not be stolen (protective response). Game status, including total score, press counts, and selected options, was visible to the participants inside the scanner. Provocations, in the form of stolen points, occurred every 6\u0026ndash;60 seconds if the participants did not select Option 2 or Option 3. Completing Option 2 or Option 3 initiated a maximum 60-second provocation-free period, though participants were only explicitly informed about the protective effect of Option 2. Participants were told that while they could not keep points stolen from the opponent, the opponent retained stolen points. Hence, Option 2 reflected aggressive behaviour without direct monetary gain. Participants were provided with oral instructions about the PSAP, prior to scanning. Inside the scanner, participants completed a one-minute practice trial before engaging in a 12-minute PSAP session. The paradigm was implemented using E-prime\u0026reg; v2.0 (Psychological Software Tools, Pittsburgh, PA). Behavioural outcomes included the total points earned, the number of provocations received, and the counts of presses for each option. Additionally, a PSAP aggression score was calculated as: (1000 x Number of Option 2) / (Total button presses x Number of provocations) (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eMRI acquisition, pre-processing, and analysis\u003c/h3\u003e\n\u003cp\u003eStructural and functional MRI was performed using a 3.0 Tesla whole-body MRI scanner (Achieva dStream, Philips Medical Systems, Best, The Netherlands) with a 32-channel head coil. A total of 240 dynamic whole-brain scans were collected using a T2*-weighted gradient echo-planar imaging (EPI) fMRI sequence with the following parameters: repetition time (TR)\u0026thinsp;=\u0026thinsp;3000 ms, echo time (TE)\u0026thinsp;=\u0026thinsp;30 ms, flip angle\u0026thinsp;=\u0026thinsp;90\u0026deg;, matrix size\u0026thinsp;=\u0026thinsp;100 x 97, 43 slices, slice thickness\u0026thinsp;=\u0026thinsp;2.8 mm, and acquisition time\u0026thinsp;=\u0026thinsp;12:11 min. The resulting images had a voxel size of 1.88 x 1.88 x 2.8 mm\u0026sup3;. For anatomical reference, T1-weighted whole-brain scans were acquired using an MPRAGE sequence with the following parameters: TR\u0026thinsp;=\u0026thinsp;8.3 ms, TE\u0026thinsp;=\u0026thinsp;3.8 ms, flip angle\u0026thinsp;=\u0026thinsp;8\u0026deg;, matrix size\u0026thinsp;=\u0026thinsp;256 x 256, 220 slices, slice thickness\u0026thinsp;=\u0026thinsp;1 mm, and acquisition time\u0026thinsp;=\u0026thinsp;3:50 min. The resulting images had a voxel size of 0.94 x 0.94 x 1 mm\u0026sup3;. fMRI data preprocessing and analysis steps were performed in Statistical Parametric Mapping (SPM12, Wellcome Centre for Human Neuroimaging, University College London, London, UK) implemented on Matlab, R2022b. The functional volumes were spatially realigned to the first image, unwarped, and corrected for slice timing before being co-registered with the anatomical scan, normalized into Montreal Neurological Institute space, and smoothed using a 4mm FWHM Gaussian filter. Outlier volumes were identified based on signal density (\u0026gt;\u0026thinsp;4) and motion (\u0026gt;\u0026thinsp;2 mm) using the Artifact Detection Tools (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://www.nitrc.org/projects/artifact_detect\u003c/span\u003e\u003cspan address=\"http://www.nitrc.org/projects/artifact_detect\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e), and thereafter censored in the first-level fMRI analysis.\u003c/p\u003e \u003cp\u003eFirst-level analysis of blood-oxygen-level-dependent (BOLD) signal change was performed by modelling the following conditions: Monetary Response (the first ten seconds of Option 1), Aggressive Response (duration of Option 2), Protective Response (duration of Option 3), Winning Reward (event, at end of Option 1), Stealing Reward (event, at end of Option 2) and Provocation (event, at time of provocation). The first 10 seconds of the Monetary Response (Option 1) were used as a baseline condition, as previously described in (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e), to limit confounding effects from reward processing. If a provocation occurred during this period, the time from the beginning of Option1 until the provocation started was used. Single-subject design matrices, including these task conditions and the six head movement regressors obtained during spatial realignment, were estimated using general linear models to determine condition-specific BOLD responses, with the canonical HRF plus time-derivative. The following contrasts were computed: Provocation\u0026thinsp;\u0026gt;\u0026thinsp;Monetary Response, Aggressive Response\u0026thinsp;\u0026gt;\u0026thinsp;Monetary Response, Winning Reward\u0026thinsp;\u0026gt;\u0026thinsp;Monetary Response, Stealing Reward\u0026thinsp;\u0026gt;\u0026thinsp;Monetary Response, and Protective Response\u0026thinsp;\u0026gt;\u0026thinsp;Monetary Response.\u003c/p\u003e \u003cp\u003eThe generated single-subject contrast maps were then used for the second-level fMRI analysis to examine task-related brain reactivity over the whole group. Based on the previously described PSAP neural correlates (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e), a region of interest (ROI) approach was employed. The ROIs were defined according to the AAL3 atlas, and included the left and right amygdala, striatum (putamen and caudate nuclei), ACC (subgenual, supgenual and pregenual areas), insula, and PFC (lateral and medial parts of the superior frontal gyrus, middle frontal gyrus, opercularis, triangularis and orbitalis parts of the inferior frontal gyrus).\u003c/p\u003e\n\u003ch3\u003eStatistical analyses\u003c/h3\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eRandomized Controlled Trial\u003c/h2\u003e \u003cp\u003eUsing an intention-to-treat approach, the primary analyses were conducted using unblinded data from all participants with sufficient data. Differences between the two treatment groups in treatment response and remission status at the end of trial were assessed using χ\u003csup\u003e2\u003c/sup\u003e tests. To further evaluate the treatment effect on the overall symptom burden, we performed an analysis of variance with repeated measures of the DRSP total score. \u0026lsquo;Time\u0026rsquo; was included as within-subject variable, with time points (baseline and follow-up) treated as repeated measures, and \u0026lsquo;Treatment\u0026rsquo; (escitalopram or placebo) was entered as a fixed factor. An interaction term between treatment and time was included to assess the treatment effect. Similarly, we tested the Treatment x Time interaction effects on the DRSP subscales to further delineate the treatment effects across symptom dimensions. Multiple testing corrections were applied for the DRSP subscales using the False Discovery Rate (FDR)(four tests). Post-hoc independent-samples Mann-Whitney U Tests were run to assess the difference in DRSP scores at follow-up between treatment group, with effect sizes given as Cohen\u0026rsquo;s d. All analyses were performed using SPSS for Windows, version 28.0.1.0 (IBM, Armonk, NY), with a significance threshold set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003ePSAP behaviour and aggression\u003c/h2\u003e \u003cp\u003eAs many of the relevant behavioral variables in PSAP were not normally distributed (significant Shapiro-Wilk tests), independent \u003cem\u003et\u003c/em\u003e-tests with bootstrapped mean differences (bootstrap replicates\u0026thinsp;=\u0026thinsp;1,000, using the \u003cem\u003eboot\u003c/em\u003e package for R, version 4.4.2) were conducted to compare the groups in terms of behavioral outcomes (total points earned, number of provocations received, counts of presses for each option and aggression score).\u003c/p\u003e \u003cp\u003eChanges in aggressiveness levels assessed with the total AQ-RSV score, in relation to escitalopram treatment, were investigated using an analysis of variance with repeated measures of the AQ-RSV total score. \u0026lsquo;Time\u0026rsquo; was included as within-subject variable, with time points (baseline and follow-up) treated as repeated measures, and \u0026lsquo;Treatment\u0026rsquo; (escitalopram or placebo) was entered as a fixed factor. An interaction term between treatment and time was included to assess the treatment effect. Post-hoc comparisons were carried out using one-sided two-sample and paired t-tests in SPSS for Windows, version 28.0.1.0 (IBM, Armonk, NY). A mediation analysis was conducted using the PROCESS macro for SPSS (Model 4, (\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e)) to examine whether irritability levels (mediator) mediated the effect of treatment (independent variable) on aggressiveness (AQ-RSV score, dependent variable). Bootstrapped confidence intervals (5,000 resamples) were used to test the significance of the indirect effect, as this approach provides a more robust estimate by accounting for the non-normality of the sampling distribution of the mediation effect.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eFunctional MRI\u003c/h2\u003e \u003cp\u003eThe second-level fMRI analyses consisted in examining the task-related brain reactivity over the whole sample and delineating treatment group differences across the task conditions. One sample t-tests were run within masks of the predefined ROIs, to define brain reactivity to provocations, aggressive response, protective response, stealing points, and winning points. Condition-specific activations were visualized using a voxel-level significance threshold of p\u003csub\u003euncorrected\u003c/sub\u003e \u0026lt; 0.001, with region-specific cluster extent thresholds of p\u003csub\u003eFWE\u003c/sub\u003e \u0026lt; 0.05 (Family-wise error correction). The extent thresholds were as follows: k\u0026thinsp;\u0026ge;\u0026thinsp;33 for PFC; k\u0026thinsp;\u0026ge;\u0026thinsp;12 for ACC; k\u0026thinsp;\u0026ge;\u0026thinsp;17 for the insulae; k\u0026thinsp;\u0026ge;\u0026thinsp;15 for the striatum; and k\u0026thinsp;\u0026ge;\u0026thinsp;4 for the amygdalae. To ensure that only task-responsive areas were assessed in terms of treatment group differences at follow-up, mean contrast estimates from statistically significant task-responsive clusters within ROIs were extracted. Differences in task-related brain activation across conditions were examined between treatment groups (escitalopram, placebo) using two-sample t-tests and Mann-Whitney U tests. FDR correction for multiple testing across the tested clusters\u0026rsquo; data was applied. A mediation analysis was conducted using the PROCESS macro for SPSS (Model 4) to examine whether brain reactivity to the task conditions, within areas showing a significant treatment effect, mediated the relationship between treatment and irritability.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e- Participants\u0026rsquo; characteristics\u003c/h2\u003e \u003cp\u003eIn total, 62 women with PMDD participated in the study, and were randomized to either escitalopram (n\u0026thinsp;=\u0026thinsp;33, SSRI group) or placebo (n\u0026thinsp;=\u0026thinsp;29, placebo group). The CONSORT diagram of the randomized control trial is presented in Supplementary Fig.\u0026nbsp;1. Six participants discontinued the treatment (four in the SSRI group, two in the placebo group), resulting in a dropout rate of 11.3%. In the SSRI group, three participants stopped taking the treatment due to side effects, and one stopped due to personal reasons. Two of these participants continued to fill in the DRSP and were therefore included in the analysis, following an intention-to-treat approach. Likewise, one participant in the placebo group discontinued the treatment due to personal reasons but continued to fill in the DRSP, and was included in the analysis. Commonly reported side effects included nausea, headache, and dizziness. One participant reported a worsening of anxiety and depression, as well as concentration problems upon the first escitalopram intake.\u003c/p\u003e \u003cp\u003eThe demographic and clinical characteristics of the study sample are summarized in Supplementary Table\u0026nbsp;1. Overall, women included in the study were 34\u0026thinsp;\u0026plusmn;\u0026thinsp;6 years old (mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation), had a healthy body mass index (24.6\u0026thinsp;\u0026plusmn;\u0026thinsp;4.4), and had an average cycle length of 28.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5 days. Most participants were married or cohabiting, working part- or full-time, and had a high education level. Over a third had a history of depressive episodes, and about 16% had a history of anxiety. The self-reported duration of PMDD was 11\u0026thinsp;\u0026plusmn;\u0026thinsp;7 years, on average. Over the whole sample, more than 75% had previously been treated for PMDD, primarily with antidepressants, and secondarily with hormonal and psychological treatments. Among those who had previously used antidepressants, 40% had terminated the treatment due to non-response, and 49% due to side effects. The two treatment groups did not differ in any of the demographic, hormonal, and clinical characteristics (Supplementary Table\u0026nbsp;1, Supplementary Fig.\u0026nbsp;2).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e- Escitalopram efficacy in PMDD\u003c/h2\u003e \u003cp\u003eThirty-one women allocated to escitalopram treatment and twenty-seven women allocated to placebo treatment were included in the analysis of treatment effects. In each group, two participants failed to provide sufficient DRSP ratings during the RCT (dropped out of the study) and were excluded from the analysis. Participants in the SSRI group took escitalopram for an average of 10.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8 days (mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation), while participants in the placebo group took the treatment for 10.1\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9 days, on average. In both treatment groups, treatment duration did not relate to the extent of symptom change (Supplementary Fig.\u0026nbsp;3).\u003c/p\u003e \u003cp\u003eSignificant treatment-by-time effects on DRSP scores were detected, indicating differential patterns of symptom severity change over time in the two treatment groups. These effects included the total DRSP score (F\u0026thinsp;=\u0026thinsp;6.24, p\u003csub\u003eFDR\u003c/sub\u003e=0.019), the DRSP depression score (F\u0026thinsp;=\u0026thinsp;8.07, p\u003csub\u003eFDR\u003c/sub\u003e=0.015), the DRSP affective lability score (F\u0026thinsp;=\u0026thinsp;6.64, p\u003csub\u003eFDR\u003c/sub\u003e=0.019), and the DRSP irritability score (F\u0026thinsp;=\u0026thinsp;8.80, p\u003csub\u003eFDR\u003c/sub\u003e=0.015). At follow-up, significant group differences in these DRSP scores further indicated that escitalopram treatment was associated with a clear decrease in symptom severity compared to placebo (medium to large effect sizes, Supplementary Table\u0026nbsp;2). A graphical representation of the change in symptom severity from baseline to end of trial in each treatment group is given in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The two groups did not differ in terms of remission at the end of the trial (SSRI: n\u0026thinsp;=\u0026thinsp;23 non-remitters, n\u0026thinsp;=\u0026thinsp;8 remitters; placebo: n\u0026thinsp;=\u0026thinsp;22 non-remitters, n\u0026thinsp;=\u0026thinsp;5 remitters; Χ\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.44, p\u0026thinsp;=\u0026thinsp;0.51). However, a higher treatment response rate was observed in the SSRI group compared to placebo (SSRI: n\u0026thinsp;=\u0026thinsp;15 responders, n\u0026thinsp;=\u0026thinsp;6 non-responders; placebo: n\u0026thinsp;=\u0026thinsp;6 responders, n\u0026thinsp;=\u0026thinsp;21 non-responders; Χ\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;4.28, p\u0026thinsp;=\u0026thinsp;0.04).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e- Task behaviour, aggressiveness, and brain reactivity\u003c/h2\u003e \u003cp\u003eThe two groups performed the PSAP similarly, in terms of option choices, button presses, and the PSAP aggression score (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB, Supplementary Table\u0026nbsp;3). Of note, the PSAP aggression score was not correlated with the AQ-RSV scores at follow-up with in any treatment group (Placebo: r = -0.15, p\u0026thinsp;=\u0026thinsp;0.52; SSRI: ρ = -0.04, p\u0026thinsp;=\u0026thinsp;0.87; Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eC).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eNo significant group-by-time effect on AQ-RSV scores was found (F\u0026thinsp;=\u0026thinsp;2.62, p\u0026thinsp;=\u0026thinsp;0.11). However, the treatment groups displayed a significant difference in the total AQ-RSV score at follow-up (t\u0026thinsp;=\u0026thinsp;1.87, p\u0026thinsp;=\u0026thinsp;0.03, Cohen\u0026rsquo;s d\u0026thinsp;=\u0026thinsp;0.55), and the escitalopram group displayed a significant decrease in AQ-RSV scores from baseline to follow-up (t=-2.07, p\u0026thinsp;=\u0026thinsp;0.02, Cohen\u0026rsquo;s d=-0.42), while the scores remained stable in the placebo group (t=-.89, p\u0026thinsp;=\u0026thinsp;0.19, Cohen\u0026rsquo;s d=-0.18) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eD). In order to test whether the effect of treatment on AQ-RSV scores could be mediated by the decrease in the severity of irritability, we evaluated associations between AQ-RSV scores and DRSP irritability scores before treatment. A positive association was observed between aggressiveness scores (AQ-RSV) and the severity of irritability (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eE). At follow-up, the DRSP irritability scores remained positively associated with the AQ-RSV scores, while no significant correlation was observed between irritability and the PSAP aggression score (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eF). A mediation analysis was then conducted to examine whether irritability levels mediated the effect of treatment on aggressiveness levels (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eG). Treatment significantly predicted irritability and irritability significantly predicted aggressiveness, while the total effect of treatment on aggressiveness did not reach statistical significance (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eG). Notably, the direct effect of treatment on aggressiveness, when controlling for irritability, was further reduced. The indirect effect of treatment on aggressiveness through irritability was statistically significant (95% CI [\u0026minus;\u0026thinsp;11.48, \u0026minus;\u0026thinsp;0.45]), indicating that irritability mediated the relationship between treatment and aggressiveness (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eG). The partially standardized indirect effect was \u0026minus;\u0026thinsp;0.32 (95% CI [\u0026minus;\u0026thinsp;0.77, \u0026minus;\u0026thinsp;0.03]), suggesting a moderate effect size, and a significant mediation effect.\u003c/p\u003e \u003cp\u003eIn terms of neural correlates of the PSAP, provocations elicited significant brain activation within the PFC, ACC, amygdala, insula, and striatum across all participants (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). During the aggressive response, sub-regions of the PFC, ACC, right insula and striatum showed significant activations (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Winning points during the task was associated with brain reactivity within the PFC, insula and striatum Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Details about the precise location and magnitude of the main task effects on brain reactivity within ROIs are presented in Supplementary Table\u0026nbsp;4. We found no significant main effects of the PSAP \u0026rsquo;Stealing\u0026rsquo; and \u0026rsquo;Protective response\u0026rsquo; conditions in any ROI.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003e- Effect of escitalopram on neural correlates of aggression\u003c/h2\u003e \u003cp\u003eThirty-seven participants presented valid fMRI data at follow-up (SSRI group: n\u0026thinsp;=\u0026thinsp;18; placebo group: n\u0026thinsp;=\u0026thinsp;19; Supplementary Fig.\u0026nbsp;2). Among those, three chose the aggressive option of the PSAP less than two times, and were therefore excluded from the analyses involving this task condition (SSRI group: n\u0026thinsp;=\u0026thinsp;2; placebo group: n\u0026thinsp;=\u0026thinsp;1). A flowchart of the neuroimaging study sample is presented in Supplementary Fig.\u0026nbsp;4.\u003c/p\u003e \u003cp\u003eDifferent reactivity to provocations was observed in the left anterior insula, with the BOLD signal being lower in the escitalopram group than in the placebo group (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eA); however, this effect did not survive correction for multiple comparisons across the tested clusters (Supplementary Table S5). No significant correlation was found across all participants between the anterior insula reactivity to provocation and both the PSAP aggression score and the AQ-RSV score at follow-up (Supplementary Fig.\u0026nbsp;5). A positive association between activations in the anterior insula and the follow-up DRSP irritability scores was observed across all participants (ρ\u0026thinsp;=\u0026thinsp;0.39, p\u0026thinsp;=\u0026thinsp;0.016), suggesting that a greater engagement of this region in response to provocation relates to a higher degree of irritability (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eB). Although bivariate analyses indicated an effect of treatment on insular reactivity to provocation, as well as an association between brain reactivity in this region and the severity of irritability, a mediation analysis did not support an indirect effect of treatment on irritability mediated by insular reactivity (coefficient\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.10, 95% CI [\u0026minus;\u0026thinsp;0.60, 0.52]). This suggests that while brain reactivity to provocation in the left anterior insula is related to both variables, it does not statistically account for the effect of treatment on irritability. Of note, no significant group differences in brain reactivity were observed during the aggressive response and winning reward task conditions (Supplementary Tables\u0026nbsp;6\u0026ndash;7).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe present pharmaco-neuroimaging study describes neural correlates of aggression in response to provocation in women with PMDD treated intermittently with escitalopram vs. placebo. The RCT demonstrates symptom domain-specific amelioration in PMDD symptoms by intermittently administered escitalopram. Dosage of 20 mg/day for up to fifteen luteal days led to a significant reduction in total DRSP scores, as well as scores of core mood symptoms such as anger and irritability, affect lability and depression, when compared to placebo.\u003c/p\u003e \u003cp\u003eThe findings confirm, in line with the literature, the strongest effects of SSRIs to be on anger and irritability, followed by affective lability and depression. Indeed, symptom-onset treatment has consistently been shown to primarily target mood-related symptoms\u0026mdash;such as anger, irritability, and affective lability \u0026mdash; rather than somatic symptoms, changes in appetite, or lack of energy (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). Moreover, as seen in SSRI treatment for depression, where certain symptoms (e.g., sleep disturbances and sexual dysfunction) may overlap with common medical side effects (\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e), the escitalopram group in the present study reported increased sleep disturbances and energy loss (see Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This underscores the importance of evaluating SSRI treatment effect specifically on the symptoms they are intended to target\u0026mdash;the core PMDD-symptoms.\u003c/p\u003e \u003cp\u003eIntermittent escitalopram treatment led to a significant reduction in self-reported aggressiveness, as reflected in the decreased AQ-RSV scores observed exclusively in the group receiving escitalopram. Importantly, a positive association was observed between aggressiveness and irritability, both before and after treatment, reinforcing the link between these symptom dimensions in PMDD. However, no such relationship was found between irritability and PSAP aggression scores, suggesting that the PSAP may not fully capture the behavioral consequences of irritability in this population. A mediation analysis revealed that the reduction in aggressiveness following SSRI treatment was partly driven by improvements in irritability, with a statistically significant mediating effect. This finding highlights the role of irritability as a key mechanism through which SSRIs influence aggressiveness in PMDD. The moderate effect size further suggests that while serotonergic modulation effectively alleviates irritability, additional factors may contribute to the persistence of aggressive traits. Future studies should explore how individual differences in aggression regulation and interpersonal functioning influence treatment response, as well as investigate alternative behavioral measures that better capture the real-world impact of irritability and aggression in PMDD.\u003c/p\u003e \u003cp\u003eOur functional neuroimaging findings align with previous research on the neural correlates of reactive aggression and provocation reactivity during the PSAP, implicating a network of regions involved in emotion processing and regulation (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e). As expected, provocations elicited significant activation in key regions associated with aggression regulation, including the PFC, ACC, amygdala, insula, and striatum. Our findings suggest that intermittent escitalopram treatment can influence insular activity and this? is associated with reductions in affective PMDD symptoms, such as anger and irritability. Specifically, escitalopram appeared to dampen anterior insula reactivity to provocation, though this effect was relatively small. The anterior insula plays a well-established role in reactive aggression and processing negative emotional states triggered by provocation, which can lead to impulsive aggressive behavior (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e). Prior research has also highlighted a modulatory role of serotonin in aggression-related neurocircuitry, including effects on insular activity (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). Additionally, neuroimaging studies suggest that the insula is involved in emotional processing in PMDD (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e). Notably, PMDD patients have been showed to exhibit heightened insular reactivity to socially relevant stimuli during the luteal phase, compared to healthy controls (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e). Since the PSAP includes a social component \u0026mdash; where participants perceive provocation from a fictitious opponent \u0026mdash; our findings may indicate that escitalopram modulates neural circuits involved in processing social cues in PMDD. Although our results must be interpreted with caution due to the exploratory nature of the study and the lack of statistical correction for multiple comparisons, they align with prior research suggesting that prosocial behaviors are linked to intact or enhanced serotonin function (\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAlong the line of blunted top-down regulatory activation (\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e) and heightened emotional processing (\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e) in PMDD (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e), the present findings of reduced insular activation upon treatment with escitalopram complement the ones showing higher fronto-cortical activation upon treatment with a selective progesterone receptor modulator (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e). Interstingly, progesterone antagonism was associated with enhanced top-down control during aggressive responses \u0026mdash; suggesting potential effects on cognitive regulation, which can be understood as complementary to the here observed decreased anterior insula reactivity to provocation, pointing to a downregulation of emotional processing. Importantly, the amygdala, ACC and PFC seem involved in PMDD pathophysiology (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e) and are core components of the neural network underlying reactive aggression (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). Thus, our findings of reduced anterior insula involvement in response to provocations should be considered within the broader context of this network\u0026rsquo;s role in PMDD symptomatology.\u003c/p\u003e \u003cp\u003eNotably, while anterior insula activation was significantly associated with irritability at follow-up, the mediation analysis did not support insular reactivity as an indirect pathway explaining treatment effects on irritability. This suggests that although the anterior insula is engaged in processing provocations and linked to irritability, its role in mediating the SSRI effects on aggression remains unclear. Furthermore, the lack of significant group differences in brain responses during aggressive behavior suggests that escitalopram\u0026rsquo;s effects may be specific to processing provocations, rather than the expression of aggressiveness itself. Future studies with larger samples and more targeted analyses are needed to further elucidate the mechanisms underlying SSRI effects on aggression-related neural circuitry.\u003c/p\u003e \u003cp\u003eThe present findings should be interpreted in light of methodological considerations. Treatment duration did not influence therapeutic response in this study (Supplementary Fig.\u0026nbsp;4). This is in line with the finding of rapid effect onset of SSRIs (Steinberg et al. 2012) and maximal efficacy gain of escitalopram within the first treatment cycle in PMDD (Eriksson et al. 2008a). It is indeed well established that SSRIs show selective action in PMDD, targeting specific symptom dimension (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e), with intermittent treatment demonstrating an effect comparable to continuous treatment (\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe observed significant amelioration in irritability and anger upon treatment with escitalopram vs. placebo was not paralleled by behavioral differences in reactive aggression, as measured by the PSAP. Despite significant reductions in mood symptoms, previous studies using the PSAP have not observed behavioral changes in response to medical treatments for premenstrual dysphoria (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e). A recent crossover study of patients with severe premenstrual irritability and anger found no behavioral differences in aggression during intermittent escitalopram treatment compared to placebo (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). Similarly, no differences in PSAP outcomes were observed in a RCT with selective progesterone receptor modulator (SPRM) treatment vs. placebo (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e). The PSAP is an established test for assessing reactive aggression and has been widely used to examine how psychotropic drugs influence this behavior (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e). A potential explanation for the lack of behavioral findings is that this laboratory task does not capture all aspects of reactive aggression but primarily measures punishment in response to provocation. This may miss to reflect the typical behavioral consequences of irritability and anger in PMDD, as the impairment mainly appears in home relationships, especially with one\u0026rsquo;s partner or children (\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e). Another potential explanation is that aggressive behavior tendencies differ between genders (\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e), with women more likely to employ indirect aggression (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e, \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e), which is not specifically captured in the PSAP. Sex- and disorder-tailored tasks designed to focus on behavioral aspects of interpersonal interactions may therefore more accurately capture the impairments and consequences of PMDD symptoms, as, in addition to anger/irritability, interpersonal issues such as rejection sensitivity and conflicts are among the most prevalent and debilitating symptoms of PMDD (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn summary, this pharmaco-neuroimaging study provides insights into the neural and behavioral effects of intermittent escitalopram treatment in women with PMDD. Escitalopram effectively alleviated core mood symptoms such as anger, irritability, and affective lability, though no significant behavioral changes in reactive aggression were detected using the PSAP. Neuroimaging findings revealed reduced activation in the left anterior insula during provocation in the escitalopram group, suggesting that serotonergic modulation may influence neural mechanisms underlying affective symptoms in PMDD. These results contribute to the growing evidence that SSRIs selectively target mood-related PMDD symptoms and highlight the need for more tailored behavioral paradigms to capture the interpersonal and context-dependent nature of aggression in PMDD.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cu\u003eAcknowledgments\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to thank Lena Moby and Sara Nyback for their help with data collection. We are additionally grateful to the Neuropsychopharmacology group for their valuable support.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eConflict of interest\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eThe study drugs were supplied by Lundbeck, Sweden; however, the company had no further involvement in the study\u0026apos;s design, data collection, analysis, interpretation of findings, or manuscript preparation. ISP has occasionally served on advisory boards or as an invited speaker at scientific meetings for Asarina Pharma, Bayer Health Care, Gedeon Richter, Peptonics, Shire/Takeda, Sandoz, and Lundbeck A/S. EE has been on advisory boards and/or received speaker\u0026apos;s honoraria and/or research grants from H Lundbeck and Janssen. All other authors declare no conflicts of interest.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eFunding\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eThis study was funded by the Swedish Research Council (2015-00495, 2016-01439, 2020-01801, 2021-03089), the Swedish Society of Medicine (SLS-573171, SLS-597211, SLS-789101), and the Swedish Brain Foundation (2020-0255). Additionally, EC received funding from the Swedish Research EU FP7-People-Cofund (INCA 600398) and SciLifeLab.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eEpperson CN, Steiner M, Hartlage SA, Eriksson E, Schmidt PJ, Jones I, et al. (2012): Premenstrual dysphoric disorder: evidence for a new category for DSM-5. \u003cem\u003eAm J Psychiatry\u003c/em\u003e. 169:465-475.\u003c/li\u003e\n\u003cli\u003eHartlage SA, Freels S, Gotman N, Yonkers K (2012): Criteria for premenstrual dysphoric disorder: secondary analyses of relevant data sets. \u003cem\u003eArch Gen Psychiatry\u003c/em\u003e. 69:300-305.\u003c/li\u003e\n\u003cli\u003eComasco E, Kopp Kallner H, Bixo M, Hirschberg AL, Nyback S, de Grauw H, et al. (2021): Ulipristal Acetate for Treatment of Premenstrual Dysphoric Disorder: A Proof-of-Concept Randomized Controlled Trial. \u003cem\u003eAm J Psychiatry\u003c/em\u003e. 178:256-265.\u003c/li\u003e\n\u003cli\u003eRubinow DR, Schmidt PJ (2019): Sex differences and the neurobiology of affective disorders. \u003cem\u003eNeuropsychopharmacology\u003c/em\u003e. 44:111-128.\u003c/li\u003e\n\u003cli\u003eStuder E, Nilsson S, Westman A, Pedersen NL, Eriksson E (2023): Significance and Interrelationship of the Symptoms Listed in the DSM Criteria for Premenstrual Dysphoric Disorder. \u003cem\u003ePsychiatr Res Clin Pract\u003c/em\u003e. 5:105-113.\u003c/li\u003e\n\u003cli\u003ePearlstein TB, Bellew KM, Endicott J, Steiner M (2005): Paroxetine Controlled Release for Premenstrual Dysphoric Disorder: Remission Analysis Following a Randomized, Double-Blind, Placebo-Controlled Trial. \u003cem\u003ePrim Care Companion J Clin Psychiatry\u003c/em\u003e. 7:53-60.\u003c/li\u003e\n\u003cli\u003eMarjoribanks J, Brown J, O\u0026apos;Brien PM, Wyatt K (2013): Selective serotonin reuptake inhibitors for premenstrual syndrome. \u003cem\u003eCochrane Database Syst Rev\u003c/em\u003e.CD001396.\u003c/li\u003e\n\u003cli\u003eEriksson E, Ekman A, Sinclair S, Sorvik K, Ysander C, Mattson UB, et al. (2008): Escitalopram administered in the luteal phase exerts a marked and dose-dependent effect in premenstrual dysphoric disorder. \u003cem\u003eJ Clin Psychopharmacol\u003c/em\u003e. 28:195-202.\u003c/li\u003e\n\u003cli\u003eSteinberg EM, Cardoso GM, Martinez PE, Rubinow DR, Schmidt PJ (2012): Rapid response to fluoxetine in women with premenstrual dysphoric disorder. \u003cem\u003eDepress Anxiety\u003c/em\u003e. 29:531-540.\u003c/li\u003e\n\u003cli\u003eYonkers KA, O\u0026apos;Brien PM, Eriksson E (2008): Premenstrual syndrome. \u003cem\u003eLancet\u003c/em\u003e. 371:1200-1210.\u003c/li\u003e\n\u003cli\u003eSacher J, Zsido RG, Barth C, Zientek F, Rullmann M, Luthardt J, et al. (2023): Increase in Serotonin Transporter Binding in Patients With Premenstrual Dysphoric Disorder Across the Menstrual Cycle: A Case-Control Longitudinal Neuroreceptor Ligand Positron Emission Tomography Imaging Study. \u003cem\u003eBiol Psychiatry\u003c/em\u003e. 93:1081-1088.\u003c/li\u003e\n\u003cli\u003eMenkes DB, Coates DC, Fawcett JP (1994): Acute tryptophan depletion aggravates premenstrual syndrome. \u003cem\u003eJ Affect Disord\u003c/em\u003e. 32:37-44.\u003c/li\u003e\n\u003cli\u003eRoca CA, Schmidt PJ, Smith MJ, Danaceau MA, Murphy DL, Rubinow DR (2002): Effects of metergoline on symptoms in women with premenstrual dysphoric disorder. \u003cem\u003eAm J Psychiatry\u003c/em\u003e. 159:1876-1881.\u003c/li\u003e\n\u003cli\u003eEriksson E, Hedberg MA, Andersch B, Sundblad C (1995): The serotonin reuptake inhibitor paroxetin is superior to the noradrenaline reuptake inhibitor maprotiline in the treatment of premenstrual syndrome. \u003cem\u003eNeuropsychopharmacology\u003c/em\u003e. 12:167-176.\u003c/li\u003e\n\u003cli\u003eLanden M, Erlandsson H, Bengtsson F, Andersch B, Eriksson E (2009): Short onset of action of a serotonin reuptake inhibitor when used to reduce premenstrual irritability. \u003cem\u003eNeuropsychopharmacology\u003c/em\u003e. 34:585-592.\u003c/li\u003e\n\u003cli\u003eTakahashi A, Quadros IM, de Almeida RM, Miczek KA (2012): Behavioral and pharmacogenetics of aggressive behavior. \u003cem\u003eCurr Top Behav Neurosci\u003c/em\u003e. 12:73-138.\u003c/li\u003e\n\u003cli\u003eda Cunha-Bang S, Knudsen GM (2021): The Modulatory Role of Serotonin on Human Impulsive Aggression. \u003cem\u003eBiol Psychiatry\u003c/em\u003e. 90:447-457.\u003c/li\u003e\n\u003cli\u003eBubak AN, Watt MJ, Yaeger JDW, Renner KJ, Swallow JG (2020): The stalk-eyed fly as a model for aggression - is there a conserved role for 5-HT between vertebrates and invertebrates? \u003cem\u003eJ Exp Biol\u003c/em\u003e. 223.\u003c/li\u003e\n\u003cli\u003eYen JY, Chen CC, Chang SJ, Ko CH, Chen CS, Yen CF (2011): Hostility, Impulsivity, and Behavior Inhibition Among Women with PMDD. \u003cem\u003eCNS Spectr\u003c/em\u003e. 16:205-213.\u003c/li\u003e\n\u003cli\u003eGrondal M, Naslund J, Englund C, Luke TJ, Ask K, Eriksson E, et al. (2025): Intermittent escitalopram treatment and reactive aggression in women with premenstrual irritability and anger: A crossover study. \u003cem\u003eJ Affect Disord\u003c/em\u003e. 369:599-607.\u003c/li\u003e\n\u003cli\u003eAnderson CA, Bushman BJ (2002): Human aggression. \u003cem\u003eAnnu Rev Psychol\u003c/em\u003e. 53:27-51.\u003c/li\u003e\n\u003cli\u003eBerkowitz L (1993): \u003cem\u003eAggression: Its Causes, Consequences, and Control\u003c/em\u003e. McGraw-Hill.\u003c/li\u003e\n\u003cli\u003eBlair RJ (2016): The Neurobiology of Impulsive Aggression. \u003cem\u003eJ Child Adolesc Psychopharmacol\u003c/em\u003e. 26:4-9.\u003c/li\u003e\n\u003cli\u003eSkibsted AP, Cunha-Bang SD, Carre JM, Hansen AE, Beliveau V, Knudsen GM, et al. (2017): Aggression-related brain function assessed with the Point Subtraction Aggression Paradigm in fMRI. \u003cem\u003eAggress Behav\u003c/em\u003e. 43:601-610.\u003c/li\u003e\n\u003cli\u003eCherek DR (1981): Effects of smoking different doses of nicotine on human aggressive behavior. \u003cem\u003ePsychopharmacology (Berl)\u003c/em\u003e. 75:339-345.\u003c/li\u003e\n\u003cli\u003eGeniole SN, MacDonell ET, McCormick CM (2017): The Point Subtraction Aggression Paradigm as a laboratory tool for investigating the neuroendocrinology of aggression and competition. \u003cem\u003eHorm Behav\u003c/em\u003e. 92:103-116.\u003c/li\u003e\n\u003cli\u003eGolomb BA, Cortez-Perez M, Jaworski BA, Mednick S, Dimsdale J (2007): Point subtraction aggression paradigm: validity of a brief schedule of use. \u003cem\u003eViolence Vict\u003c/em\u003e. 22:95-103.\u003c/li\u003e\n\u003cli\u003eGan G, Preston-Campbell RN, Moeller SJ, Steinberg JL, Lane SD, Maloney T, et al. (2016): Reward vs. Retaliation-the Role of the Mesocorticolimbic Salience Network in Human Reactive Aggression. \u003cem\u003eFront Behav Neurosci\u003c/em\u003e. 10:179.\u003c/li\u003e\n\u003cli\u003eda Cunha-Bang S, Fisher PM, Hjordt LV, Perfalk E, Beliveau V, Holst K, et al. (2018): Men with high serotonin 1B receptor binding respond to provocations with heightened amygdala reactivity. \u003cem\u003eNeuroimage\u003c/em\u003e. 166:79-85.\u003c/li\u003e\n\u003cli\u003eKose S, Steinberg JL, Moeller FG, Gowin JL, Zuniga E, Kamdar ZN, et al. (2015): Neural correlates of impulsive aggressive behavior in subjects with a history of alcohol dependence. \u003cem\u003eBehav Neurosci\u003c/em\u003e. 129:183-196.\u003c/li\u003e\n\u003cli\u003eBertsch K, Florange J, Herpertz SC (2020): Understanding Brain Mechanisms of Reactive Aggression. \u003cem\u003eCurr Psychiatry Rep\u003c/em\u003e. 22:81.\u003c/li\u003e\n\u003cli\u003eCoccaro EF, McCloskey MS, Fitzgerald DA, Phan KL (2007): Amygdala and orbitofrontal reactivity to social threat in individuals with impulsive aggression. \u003cem\u003eBiol Psychiatry\u003c/em\u003e. 62:168-178.\u003c/li\u003e\n\u003cli\u003eKaltsouni E, Fisher PM, Dubol M, Hustad S, Lanzenberger R, Frokjaer VG, et al. (2021): Brain reactivity during aggressive response in women with premenstrual dysphoric disorder treated with a selective progesterone receptor modulator. \u003cem\u003eNeuropsychopharmacology\u003c/em\u003e. 46:1460-1467.\u003c/li\u003e\n\u003cli\u003eCherek DR, Lane SD, Pietras CJ, Steinberg JL (2002): Effects of chronic paroxetine administration on measures of aggressive and impulsive responses of adult males with a history of conduct disorder. \u003cem\u003ePsychopharmacology (Berl)\u003c/em\u003e. 159:266-274.\u003c/li\u003e\n\u003cli\u003eMarsh DM, Dougherty DM, Moeller FG, Swann AC, Spiga R (2002): Laboratory-measured aggressive behavior of women: acute tryptophan depletion and augmentation. \u003cem\u003eNeuropsychopharmacology\u003c/em\u003e. 26:660-671.\u003c/li\u003e\n\u003cli\u003eDubol M, Neill Epperson C, Lanzenberger R, Sundstrom-Poromaa I, Comasco E (2020): Neuroimaging premenstrual dysphoric disorder: A systematic and critical review. \u003cem\u003eFront Neuroendocrinol\u003c/em\u003e.100838.\u003c/li\u003e\n\u003cli\u003eA.P.A. (2013): \u003cem\u003eDiagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5) \u003c/em\u003e\u003c/li\u003e\n\u003cli\u003eSheehan DV, Lecrubier Y, Sheehan KH, Amorim P, Janavs J, Weiller E, et al. (1998): The Mini-International Neuropsychiatric Interview (M.I.N.I.): the development and validation of a structured diagnostic psychiatric interview for DSM-IV and ICD-10. \u003cem\u003eJ Clin Psychiatry\u003c/em\u003e. 59 Suppl 20:22-33;quiz 34-57.\u003c/li\u003e\n\u003cli\u003eEndicott J, Nee J, Harrison W (2006): Daily Record of Severity of Problems (DRSP): reliability and validity. \u003cem\u003eArch Womens Ment Health\u003c/em\u003e. 9:41-49.\u003c/li\u003e\n\u003cli\u003eProchazka H, Agren H (2001): Aggression in the general Swedish population, measured with a new self-rating inventory: The Aggression Questionnaire--revised Swedish version (AQ-RSV). \u003cem\u003eNord J Psychiatry\u003c/em\u003e. 55:17-23.\u003c/li\u003e\n\u003cli\u003eHayes AF (2017): \u003cem\u003eIntroduction to mediation, moderation, and conditional process analysis: A regression-based approach\u003c/em\u003e. Guilford publications.\u003c/li\u003e\n\u003cli\u003eHieronymus F, Lisinski A, Eriksson E, Ostergaard SD (2021): Do side effects of antidepressants impact efficacy estimates based on the Hamilton Depression Rating Scale? A pooled patient-level analysis. \u003cem\u003eTransl Psychiatry\u003c/em\u003e. 11:249.\u003c/li\u003e\n\u003cli\u003eLanden M, Nissbrandt H, Allgulander C, Sorvik K, Ysander C, Eriksson E (2007): Placebo-controlled trial comparing intermittent and continuous paroxetine in premenstrual dysphoric disorder. \u003cem\u003eNeuropsychopharmacology\u003c/em\u003e. 32:153-161.\u003c/li\u003e\n\u003cli\u003eMoeller FG, Dougherty DM, Swann AC, Collins D, Davis CM, Cherek DR (1996): Tryptophan depletion and aggressive responding in healthy males. \u003cem\u003ePsychopharmacology (Berl)\u003c/em\u003e. 126:97-103.\u003c/li\u003e\n\u003cli\u003eHylan TR, Sundell K, Judge R (1999): The impact of premenstrual symptomatology on functioning and treatment-seeking behavior: experience from the United States, United Kingdom, and France. \u003cem\u003eJ Womens Health Gend Based Med\u003c/em\u003e. 8:1043-1052.\u003c/li\u003e\n\u003cli\u003eHyde JS (2005): The gender similarities hypothesis. \u003cem\u003eAm Psychol\u003c/em\u003e. 60:581-592.\u003c/li\u003e\n\u003cli\u003eDenson TF, O\u0026apos;Dean SM, Blake KR, Beames JR (2018): Aggression in Women: Behavior, Brain and Hormones. \u003cem\u003eFront Behav Neurosci\u003c/em\u003e. 12:81.\u003c/li\u003e\n\u003cli\u003eDarko G, Bjorkqvist K, Osterman K (2019): Low intensity intimate partner aggression in Ghana: Support for the revised gender symmetry theory in an African country. \u003cem\u003eAggress Behav\u003c/em\u003e. 45:52-61.\u003c/li\u003e\n\u003cli\u003ePotegal M, Archer J (2004): Sex differences in childhood anger and aggression. \u003cem\u003eChild Adolesc Psychiatr Clin N Am\u003c/em\u003e. 13:513-528, vi-vii.\u003c/li\u003e\n\u003cli\u003eDambacher F, Sack AT, Lobbestael J, Arntz A, Brugman S, Schuhmann T (2015): Out of control: evidence for anterior insula involvement in motor impulsivity and reactive aggression. \u003cem\u003eSoc Cogn Affect Neurosci\u003c/em\u003e. 10:508-516.\u003c/li\u003e\n\u003cli\u003eGingnell M, Ahlstedt V, Bannbers E, Wikstrom J, Sundstrom-Poromaa I, Fredrikson M (2014): Social stimulation and corticolimbic reactivity in premenstrual dysphoric disorder: a preliminary study. \u003cem\u003eBiol Mood Anxiety Disord\u003c/em\u003e. 4:3.\u003c/li\u003e\n\u003cli\u003eMiczek KA, de Almeida RM, Kravitz EA, Rissman EF, de Boer SF, Raine A (2007): Neurobiology of escalated aggression and violence. \u003cem\u003eJ Neurosci\u003c/em\u003e. 27:11803-11806.\u003c/li\u003e\n\u003cli\u003eCrockett MJ, Clark L, Hauser MD, Robbins TW (2010): Serotonin selectively influences moral judgment and behavior through effects on harm aversion. \u003cem\u003eProc Natl Acad Sci U S A\u003c/em\u003e. 107:17433-17438.\u003c/li\u003e\n\u003cli\u003eComasco E, Hahn A, Ganger S, Gingnell M, Bannbers E, Oreland L, et al. (2014): Emotional fronto-cingulate cortex activation and brain derived neurotrophic factor polymorphism in premenstrual dysphoric disorder. \u003cem\u003eHum Brain Mapp\u003c/em\u003e. 35:4450-4458.\u003c/li\u003e\n\u003cli\u003eStiernman L, Dubol M, Comasco E, Sundstrom-Poromaa I, Boraxbekk CJ, Johansson M, et al. (2023): Emotion-induced brain activation across the menstrual cycle in individuals with premenstrual dysphoric disorder and associations to serum levels of progesterone-derived neurosteroids. \u003cem\u003eTransl Psychiatry\u003c/em\u003e. 13:124.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[{"identity":"e434f424-923d-4d65-9035-1c505e53befb","identifier":"10.13039/501100004359","name":"Vetenskapsrådet","awardNumber":"2015-00495","order_by":0}],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Uppsala University","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"aggressiveness, brain, depression, female, functiona magnetic resonance imaging, hormones, premenstrual dysphoric disorder, randomized controlled trial, selective serotonin reuptake inhibitor ","lastPublishedDoi":"10.21203/rs.3.rs-6224514/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6224514/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground:\u003c/h2\u003e \u003cp\u003ePremenstrual dysphoric disorder (PMDD) is a depressive disorder linked to the menstrual cycle, notably characterized by the cyclic occurrence of emotional distress. A core symptom is irritability or anger, whose outcome can be aggressiveness. Intermittent selective serotonin reuptake inhibitor (SSRI) treatment has shown promise in alleviating symptoms, yet the neural underpinnings of its rapid efficacy remain unknown. This randomized controlled trial aimed to evaluate the impact of intermittent SSRI treatment for PMDD on aggression-related brain function.\u003c/p\u003e\u003ch2\u003eMethods:\u003c/h2\u003e \u003cp\u003eWomen with PMDD (n\u0026thinsp;=\u0026thinsp;62) were randomized to receive either intermittent escitalopram (20mg/day) or placebo during the luteal phase of the menstrual cycle. Symptoms were assessed using the Daily Record of Severity of Problems. Functional magnetic resonance imaging (fMRI) was conducted in combination with the Point Subtraction Aggression Paradigm (PSAP) to evaluate neural responses to aggression-related stimuli.\u003c/p\u003e\u003ch2\u003eResults:\u003c/h2\u003e \u003cp\u003eIntermittent escitalopram treatment significantly reduced PMDD symptoms compared to placebo, particularly irritability or anger. Aggressiveness, that was positively associated with these key symptoms, diminished as an effect of treatment, with irritability mediating the relationship between treatment and aggressiveness. Reactivity to provocations was associated with lower activation of the anterior insula upon treatment with escitalopram, which also positively related to irritability.\u003c/p\u003e\u003ch2\u003eConclusions:\u003c/h2\u003e \u003cp\u003eThese findings suggest a potential neural mechanism underlying the therapeutic effects of SSRIs in PMDD and provide insights into their role, in an interplay with gonadal hormones, in modulating reactive aggression.\u003c/p\u003e","manuscriptTitle":"Escitalopram intermittent use and brain reactivity to aggressive stimuli in premenstrual dysphoric disorder","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-03-18 07:58:47","doi":"10.21203/rs.3.rs-6224514/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"af46161f-2c7c-4026-ae04-68ac8e76c658","owner":[],"postedDate":"March 18th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-03-18T07:58:47+00:00","versionOfRecord":[],"versionCreatedAt":"2025-03-18 07:58:47","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6224514","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6224514","identity":"rs-6224514","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}