DeNPRU-QM Responsive project: Prevalence of memory complaints in the absence of objective symptoms in clinical populations: systematic review update

DeNPRU-QM Responsive project: Prevalence of memory complaints in the absence of objective symptoms in clinical populations: systematic review update | 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 Systematic Review DeNPRU-QM Responsive project: Prevalence of memory complaints in the absence of objective symptoms in clinical populations: systematic review update Jasmine Shaw, Malvika Muralidhar, Harriet Demnitz-King, Greta Rait, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8165369/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 – Current pathways for assessment and treatment of memory disorders are designed for people with dementia but are also accessed by people with subjective cognitive decline without objective deficits (SCD), or with cognitive deficits likely to be of psychological causation without neurodegeneration (Functional Cognitive Disorders, FCDs). We aimed to identify how frequently adults meeting SCD/FCD criteria, arguably better served by different service models, present to health services. Methods – Updating a previous review, we searched MEDLINE, Embase, and PsycINFO for studies reporting SCD/FCD prevalence within representative clinical samples, published between 2019 and 2025. We assessed study quality using the RoB-PrevMH tool and synthesised data using similar methods to the previous review. Results – We included 5/21 high- and 16/21 moderate-quality studies. The pooled mean age was 73.3 years (Standard Deviation = 7.0; N = 12,785) and 55.1% of participants were female. Across studies reporting SCD (k = 20; n = 13,155) and FCD (k = 3; n = 4,551), pooled prevalences were 17.3% and 5.6% respectively. Most studies (k = 11; 52.4%) did not explicitly exclude pseudodementia related to psychiatric illnesses. In high quality studies that did, SCD prevalence was 11.4% ( k = 3, n = 3,295; 10.2–14.1%) in memory clinic attendees and 16.5% ( k = 1, n = 91) among primary care attendees aged 50 + presenting with cognitive complaints without pre-existing dementia. Conclusions – At least 10% of people presenting to memory services are diagnosed with SCD and fewer with FCD. We need consistent guidelines about how these conditions are defined and diagnosed. An integrated, multidisciplinary, neighbourhood health service would be well positioned to treat these groups. Psychiatry dementia cognitive decline cognitive impairment neurocognitive disorders neurodegenerative diseases Figures Figure 1 Key message What is already known on this topic Current pathways for assessment and treatment of memory disorders are designed for people with dementia but are also accessed by people with subjective cognitive decline without objective deficits (SCD), or with cognitive deficits likely to be of psychological causation without neurodegeneration (Functional Cognitive Disorders, FCDs). What this study adds This study updated a systematic review, identifying recent evidence for the prevalence of SCD or FCD among people presenting to any clinical setting, to inform the development of treatment pathways for people presenting with these symptoms. At least 10% of people presenting to memory services are diagnosed with SCD and fewer are diagnosed with FCD. We need consistent guidelines about how these conditions are defined and diagnosed. An integrated, multidisciplinary, neighbourhood health service would be well positioned to treat these groups. How this study might affect research, practice or policy Identifying the prevalence of SCD/FCD within specific healthcare settings may inform effective treatment pathways, improving support and care quality. Investing in integrated, community older people’s mental and physical health and care services would build capacity to provide effective alternative treatment pathways for those presenting with SCD/FCD symptoms in primary care. BACKGROUND Increasing numbers of individuals, concerned they have reduced cognitive function, are approaching health services ( 1 ). While current pathways for assessment and treatment of memory disorders are designed for people with dementia, they are also accessed by people without objective cognitive deficits, or with deficits of psychological, rather than neurodegenerative causation. Arguably, these groups may be better served by different service models. Around a third of the general adult population experience subjective cognitive complaints without objective deficits ( 2 , 3 ). The term subjective cognitive decline (SCD) was conceived in 2014 to describe cognitive symptoms that are too mild to be evident on objective testing (or undetectable in those with high premorbid cognition, due to ceiling effects of current instruments) ( 4 ). Its management is often based on a model that places SCD “within the realm of degenerative brain disease and at the start of a linear trajectory towards dementia”( 2 ). A recent review reported an association between SCD and a two-fold increased risk of developing either mild cognitive impairment (MCI) or dementia ( 5 ). However, other studies indicate that while most people who develop Alzheimer’s disease and other degenerative dementias experience SCD at some time, most individuals with SCD will not show progressive cognitive decline ( 6 , 7 ). Cognitive symptoms have multiple causes, including functional cognitive disorders (FCDs), drug effects, systemic illness, brain injury, non-degenerative and degenerative brain disease ( 2 ). FCDs cause distress or functional impairment and are defined as the presence of symptom(s) of impaired cognitive function, which can be inconsistent between different situations or with observed or measured function, not better explained by another medical disorder ( 8 ). A FCD diagnosis infers a specific aetiology of cognitive symptoms (functional and non-neurodegenerative), and poses a diagnostic challenge due to its resemblance to neurocognitive disorders ( 9 ). The term FCD conceptualises the cognitive symptoms as psychogenic, relating to the somatisation of distress or worry, as opposed to symptoms occurring within a psychiatric disorder such as anxiety or depression ( 2 ). A 2023 systematic review aimed to identify diagnostic symptoms and signs that discriminate it from neurodegeneration. Patients with FCD were younger, more educated, and more often had a family history of older onset dementia. They also had abrupt symptom onset, anxiety, depression and sleep disturbance. Attending appointments alone and bringing a handwritten list of problems predicted FCD ( 10 ). Both FCD and SCD pose diagnostic challenges: FCD due to its resemblance to neurocognitive disorders ( 9 ), and SCD relating to the consistency by which it is defined and therefore the accuracy by which it can predict later neurodegeneration ( 5 ). Consequently, identification of SCD and FCD are not straightforward and there is uncertainty for both patient and clinician regarding appropriate symptom management. The English Department of Health and Social Care (DHSC) and NHS England commissioned this review, as part of a wider project to explore how treatment pathways for people presenting with these symptoms might be enhanced. A 2019 systematic review examining the prevalence of cognitive complaints in the absence of degenerative brain disease found that approximately a quarter of patients presenting to memory clinics received diagnoses suggestive of subjective cognitive impairment, pseudodementia, or FCD. Across 32 studies, these diagnoses were reported in 2,832/12,003 (24%) patients ( 2 ). We aimed to update this review by identifying recent evidence for the prevalence of SCD or FCD among people presenting to any clinical setting. METHODS Search strategy and selection criteria We searched published, peer-reviewed, English-language literature in MEDLINE, Embase, and PsycINFO databases from 1 March 2019 to 31 May 2025. Search terms for FCD/SCD were informed by the DeNPRU-QM memory service survey and previous reviews ( 1 , 2 , 10 ), combining condition- and population-specific terms with the Boolean operators ‘AND’ (between concepts) and ‘OR’ (within concepts). Reference lists of included studies and relevant reviews were screened (see Table 1S, supplementary material for search strategy). We included quantitative, observational studies reporting cross-sectional data on prevalence of patients with SCD or FCD, as defined above – however termed – among those assessed for possible cognitive disorders in healthcare settings. Eligible studies recruited more than 45 participants ( 11 ) and enrolled patients consecutively referred to or attending a clinical setting over a defined period, thereby drawing from a potentially representative sample of the target population. We excluded studies with SCD samples inclusive of patients with objective cognitive impairment due to neurodegenerative disease (e.g., mild cognitive impairment [MCI]) or related to brain injury, studies that have been retracted by journals, case series, dissertations and meeting abstracts. Quality appraisal We assessed risk of bias using the RoB-PrevMH tool ( 12 ). Two researchers (MM and JS) independently rated each study on clarity of target population definition, and three risk of bias domains related to: sampling; non-response; and information bias. Conflicts were resolved through discussion with a third author (CC). Overall, study quality was judged as ‘high’ (low risk across all domains), ‘moderate’ (any unclear risk), or ‘low’ (any high risk). Data synthesis and analysis We conducted an Egger’s test to assess risk of publication bias and used the “metafunnel” package in Stata to produce a funnel plot of effect size against standard error. We reported pooled mean age and standard deviations (SD), proportions of female participants across all included studies, and ethnicity where possible. Where studies reported median age (see Table 2S, 3S, and 4S, supplementary material for extracted data), we used these averages to approximate mean ( 13 , 14 ), providing pooled estimates using mean age only as a sensitivity analysis. We narratively synthesised findings, reporting prevalence of SCD, FCD and related concepts. Using the methods adopted by the previous review we were updating ( 2 ), we divided the number of patients with SCD or FCD by the sample sizes in clinically relevant groups, reporting pooled prevalence estimates, sample sizes and pooled mean age, SDs, and proportions of female participants. We performed sensitivity analyses to assess the stability of our findings, including random-effects prevalence meta-analysis models (reporting heterogeneity using I 2 ) where subgroup prevalence estimates were pooled (see the Appendix, supplementary material). These meta-analysis models use the inverse of the variance adjusted for between-study heterogeneity (tau-squared), thereby reducing sample size influence. They are based on Freeman-Tukey transformations, stabilising variance and reducing skewness, which were back-transformed to find prevalence estimates. FINDINGS Search results We identified 743 studies, of which 21 met our inclusion criteria (see Fig. 1 for our search results and selection process). Study quality There was high agreement between raters regarding study overall risk of bias (64/84; 76.2%). Most studies were rated moderate quality (16/21; 76.2%), primarily because they did not report sample sizes before applying exclusion criteria or obtaining consent (14/16; 87.5%). No studies had more than one RoB-PrevMH domain rated as ‘unclear’. The remaining studies (5/21; 23.8%) were rated high quality (see Table 5S, supplementary material). Over half of the included studies (13; 61.9%) reported prevalence estimates for diagnostic categories defined through standardised clinical assessment (number of studies [ k ] = 10) or use of questionnaires (k = 3) in prospectively collected data. The remaining 8 studies (38.1%) used existing databases or clinical registers, reporting diagnoses determined in routine clinical practice. Egger’s test for all included studies indicated strong evidence for publication bias (β = 13.87; [95% CI: 4.73, 23.01], p = 0.005); with smaller studies that reported higher rather than lower prevalence estimates more likely to be published (see Fig. 1 S, supplementary material). Population characteristics The included studies were conducted in: Europe (9; 42.9%) (including two UK studies); North America (5; 23.8%); Asia (3; 14.3%); South America (3; 14.3%); and Australia (1; 4.8%). The weighted pooled mean age across all studies ( N = 12,785) was 73.3 years (SD = 7.0) and 55.1% ( n = 7,048) were female. Only five studies reported ethnicity (three were high-quality), so these are reported individually ( 20 , 28 , 30 , 31 , 33 ). Definitions/concepts delineating groups with subjective cognitive decline Almost all studies reported the prevalence of concepts variously described as subjective (cognitive or memory) decline, impairment or concerns. 8/21 (38.1%) studies used the term “subjective cognitive decline” (SCD), 6 (28.6%) used “subjective cognitive impairment” (SCI), 4 (19.1%) used “subjective memory complaints” (SMC), and 3 (14.3%) used “subjective cognitive complaints” (SCC). Table 6S (supplementary material) shows how frequently terms were used, and how cases were ascertained. Definitions of subjective concerns were commonly based on criteria defined by ICD-10, or those delineated by Jessen and colleagues: normal performance on standardised cognitive tests and persistent self-experience of cognitive decline unrelated to an acute event that cannot be explained by objective cognitive impairment (e.g., dementia, MCI) or psychiatric or neurological disease ( 4 , 7 ). Definitions of functional cognitive decline/ impairment 3/21 (14.3%) studies reported the prevalence of FCD or functional cognitive impairment (FCI). Two studies defined FCD using Ball and colleagues’ criteria ( 8 ): one or more symptoms of cognitive impairment, evidence of inconsistency between the complaint and clinical assessment, and symptoms of cognitive impairment not explained by other conditions that affect daily functioning or require clinical attention ( 19 , 20 ). One of these studies included people with SCD and psychiatric disorder within their definition of FCD ( 19 ). The third study used memory clinic assessment to categorise their sample, distinguishing between those with and without objective cognitive decline and then further defining those with FCI (memory complaints without relevant neuropathology due to mental and physical health problems) ( 28 ). Reported diagnoses After pooling the samples from all studies reporting SCD prevalence ( k = 20; n = 13,155), the most common diagnosis was dementia (39.9%), followed by MCI (25.6%), SCD (17.3%), and ‘other’ conditions (including FCD; 17.2%). Among the studies reporting FCD prevalence ( k = 3; n = 4,551) the most common diagnosis was dementia (61.0%), followed by MCI (15.2%), ‘other’ conditions (including SCD; 18.2%), and FCD (5.6%). Patients presenting to primary care settings with cognitive concerns Two studies evaluated patients presenting to primary care with SCD ( 15 , 16 ). One (high-quality) study prospectively recruited 91/432 (21.1%) patients who presented to a Basic Health Unit in Brazil over a 6-month period ( 16 ). Patients were excluded from formal assessment if they were aged < 50 years (n = 157) or presented without cognitive concerns (n = 167). 15 (16.5%) patients presenting with cognitive concerns were reported to meet Jessen and colleagues’ SCD criteria ( 4 , 7 ). A second, (moderate-quality) study analysed clinical data from two cohorts from 17 primary care centres in Sweden ( 15 ). Patients aged ≥ 40 years undergoing investigation for dementia were recruited for the BioFINDER Primary Care Study ( 36 ). 140/515 (27.2%) had SCD, excluding those with psychiatric disorders. Patients referred to secondary care outpatient settings for diagnostic assessment of cognitive concerns Sixteen studies recruited from diagnostic memory disorders services. These neurology- ( k = 11), psychiatry- ( k = 2), geriatric- ( k = 2), and multidisciplinary-led ( k = 1) services were based in secondary ( k = 11) and tertiary ( k = 5) case settings. 10 (62.5%) studies reported existing diagnoses, while 6 (37.5%) recruited prospective samples, determining diagnoses through clinical assessments. Two studies were based in memory clinics in the UK ( 28 ) and Finland ( 23 ) dedicated to evaluation of early onset memory problems. High quality studies (k = 5) Three high-quality studies explicitly excluded those with psychiatric disorders from SCD samples in line with Jessen ( 4 , 7 ) and Ball ( 8 ) criteria. The UK-based study set in an early onset memory clinic prospectively recruited 348 patients (aged 38–66) referred over 2.5 years; 220 (63.2%) were White British and 128 (36.8%) from minority ethnic backgrounds. 900/1,200 referrals were deemed inappropriate using published diagnostic guidelines ( 37 ). Referrals were from primary (88.2%) and secondary care services (21.8%). 130 (37.4%) patients had ‘memory complaints without relevant neuropathy’ and 93 (26.7%) had FCI; others were diagnosed with dementia or MCI ( 28 ). Two USA-based studies, set in a Texan memory disorder clinic, used retrospective data. One recruited consecutive referrals over 6-years, the second over seven years. The former study excluded 116/1,256 not completing assessments ( 30 ). The remaining sample included 161/1,140 (14.1%) patients with SCC. The latter study included 209/1,659 (12.6%) patients with SCC ( 31 ). Both studies reported ethnicity, with the former study including 86% Caucasian, 6% African American, 4% Hispanic, and 4% other ethnicity, and the latter study very similar proportions. A Swedish study prospectively recruited all referrals to a geriatric-led memory clinic over one year. They reported 68/106 (64.2%) had SCI ( 18 ), not excluding those with psychiatric illness. Only one high quality memory service-based study evaluated the prevalence of FCD according to Ball’s criteria ( 8 ); they included SCD diagnoses in this group according to Jessen and colleagues ( 7 ). The service was a neurology-led tertiary memory clinic in Brazil, and prevalence of FCD and SCD was reported. Their sample included 146/496 (29.4%) patients with FCD; 53/146 (36.6%) were SCD diagnoses and 93/146 (63.7%) were psychiatric disorder diagnoses. The authors note that the sample was less highly educated than populations in most epidemiological studies in high income countries ( 19 ). Moderate quality studies (k = 11) A UK-based study asked 85 memory clinics to each audit the case-notes of 50 consecutive patients ( 20 ), and found that 44/3,707 (1.2%) and 16/3,707 (0.4%) of patients had SCD and FCD respectively. Of their sample, 274 (7.4%) belonged to ethnically minoritised groups, including Black, Asian, and other backgrounds. Three studies were based in Sweden. One analysed secondary data from the BioFINDER study 2 ( 38 ), (discussed above as it also recruited in primary care), finding that 139/698 (19.9%) patients met criteria for SCD ( 15 ). A second Swedish study prospectively recruited patients from nine multidisciplinary-led memory clinics ( 21 ); 104/835 (12.5%) patients with diagnoses had SCI. In the third Swedish study, participants were retrospectively sampled from a hospital electronic database and biobank for clinical research ( 29 ); 214/410 (52.2%) patients were SCI cases. A Finnish study ( 23 ) consecutively recruited memory clinic attendees younger than 65 years; 14/210 (6.7%) met SCD criteria. Two studies recruited from Greek memory clinics over different time-periods; one included 44/145 (30.3%) patients with SMC ( 27 ), the other 34/174 (19.5%) patients with SCD, for which deterioration of cognitive performance on a range of neuropsychological tests was under 10.0% ( 26 ). Two Canada-based studies used secondary data from the Rural and Remote Memory Clinic, from different time periods; one included 85/149 (57.0%) ( 22 ), the other 95/416 (22.8%) patients with SCI ( 25 ). An Australian-based study included 40/129 (31.0%) patients with SCD from the ISLAND clinic ( 17 ). Finally, a Taiwanese study retrospectively reported 53 (7.3%) SCD cases in a tertiary memory clinic sample of 727 ( 24 ). Summary of memory clinic studies In high-quality studies of memory clinic populations that excluded or identified patients with cognitive symptoms related to comorbid psychiatric illness ( k = 3; n = 2,347; mean age: 71.6; SD = 8.8; 54.4% female), 11.4% ( n = 3,295; 10.2–14.1%) of participants met SCD criteria ( 19 , 30 , 31 ). In high quality studies where concept criteria ( 4 , 7 , 8 ) were not fully operationalised (symptoms related to other medical disorders were not excluded), SCD prevalence higher (64.2%) ( 18 ) and FCD prevalence (including both SCD and psychiatric disorder diagnoses) was 29.4% ( 19 ). Two studies that recruited participants from memory clinics for people with early onset memory concerns, reported conflicting findings. In a UK study, 37.4% patients had ‘memory complaints without relevant neuropathy’ and 93 (26.7%) had FCI ( 28 ), but in a Finnish study only 14 (6.7%) had SCD, with MCI related to non-neurodegenerative causes the most frequent diagnosis ( 23 ). This variation may relate to operational or diagnostic differences between the services or studies; the Finnish study used full neuropsychological assessment to detect objective impairment, which may account for the higher proportion with MCI, relative to the UK study which used primary care screening tools. Only two studies, both from the UK, reported the prevalence of FCD/FCI amongst patients attending memory clinics (defined in line with Ball and colleagues’ ( 8 ) criteria); 0.4% FCD was found in a moderate-quality study auditing diagnoses across 85 UK memory clinic populations, and 26.7% FCI in a high-quality, prospective study evaluating patients referred to a young-onset memory clinic. Other secondary care populations (k = 4) Four moderate-quality studies described secondary care populations, for whom diagnostic evaluation of cognitive symptoms was not the primary reason for referral. One USA, moderate-quality study, recruited African American adults (mean age: 52.5; SD = 10.5; 86% female) attending a post-acute covid clinic, an average of 5 months after covid-infection ( 33 ). 4/87 (4.6%) participants had SCC, defined using scores on the Patient Reported Outcomes Measurement Information System Cognitive Function-Concerns (PROMIS-CF) short form questionnaire. The remaining three studies described populations referred for geriatric comprehensive evaluation or rehabilitation. Two used clinically assessed diagnoses to define their study groups ( 32 , 34 ). One reviewed secondary data from patients presenting to a neurology clinic in Peru for cognitive evaluation. 330/720 (45.8%) included patients met SCD criteria ( 32 ). The second study prospectively recruited patients presenting with cognitive symptoms to two rehabilitation outpatient clinics in China. Their sample ( n = 95), excluding those with clinical depression, included 34 (35.8%) patients with SCD ( 34 ). The latter study recruited patients presenting to geriatric outpatient clinics in Turkey ( 35 ). In their final sample ( n = 794), 313 (48.0%) reported SMC; defined as a positive answer to a question about whether memory concerns affect everyday life. Overall, among moderate-quality studies of populations presenting to secondary care geriatric comprehensive evaluation or rehabilitation services ( n = 1,467; mean age: 71.6 years [SD = 5.7]; 54.9% female), the pooled prevalence of SCD was 42.1% ( n = 1,609; 35.8–45.8%) ( 32 , 34 , 35 ), and among a younger population attending a post-acute covid clinic, 4.6% met SCC criteria ( 33 ). DISCUSSION There has been a considerable volume of research regarding the prevalence of SCD/FCD since a previous review found that a quarter of those referred for cognitive assessments met criteria for FCD, SCI or pseudodementia ( 2 ). We found that in high quality studies, one in ten people presenting to memory services meet criteria for SCD and fewer are diagnosed with FCD. Evidence from UK settings is limited. One higher quality study reported that a quarter of patients referred to a UK young-onset memory clinic had FCD. This is in line with a previous review indicating that FCD is more prevalent among those assessed for dementia at a younger age ( 10 ). A second UK study audited current diagnoses and found rates of FCD and SCD much lower than those reported in international, prospective studies. This might be explained by different national service models: the UK system, with access to memory services almost entirely via primary care is more heavily gate-kept than other systems. It might also reflect a lack of consistency in how these conditions are defined and diagnosed. Tools to triage patients without objective cognitive impairment from primary care away from memory clinics have been considered, including digital cognitive tests ( 18 ), biomarkers ( 15 ) and a checklist to identify those more likely to have FCD ( 39 ). But people with SCD and FCD may both benefit from being seen in a memory clinic for reassurance, and treatment of non-neurodegenerative aetiology. Even if tools were available to accurately triage these groups out of memory services, this would risk reducing the service afforded to these groups, unless alternative, more appropriate pathways for the specific needs of these distinct conditions could be developed. While biomarkers are anticipated to transform the accuracy of dementia diagnostic processes, they are currently only recommended where an objective cognitive deficit likely related to Alzheimer’s disease is suspected; a positive biomarker test of uncertain relevance could considerably exacerbate distress. The terms FCD and SCD imply causation (degenerative and psychological respectively), which can be problematic as true causation is often unclear and/or complex. Systematic evaluation of the causes of symptoms – which may include drug effects, physical and psychological illnesses is key to evidence-based treatment. We found that rates of SCD/FCD were higher in studies where psychological disorders as a cause of symptoms were not systematically excluded, suggesting that they may be contributing to many cases. Older people are least likely to receive psychological ( 40 ) and drug treatments ( 41 ) for mental disorders. Investing in older people’s mental health services would build capacity to provide effective alternative treatment pathways for those presenting with SCD/FCD symptoms in primary care. The UK 10-year health plan focus on neighbourhood-based, integrated care will bring together interdisciplinary expertise across geriatrics, primary care, neurology and psychiatry. This integrated workforce would be well positioned, if suitably skilled and resourced, to deliver the joined-up approach to care this patient group needs ( 42 ). This more integrated approach enables a more holistic, iterative consideration of symptoms, more suited to the needs of these groups. This approach could reduce distress associated with a diagnostic process often culminating in no practical help ( 43 , 44 ), deliver more effective, relevant care for this group who are at low risk of developing dementia, and save resources. The integration of health and social care will be critical too. Providing supportive cognitive wellbeing groups for people with SCD and MCI appears to improve cognition, at relatively low cost ( 45 , 46 ). Limitations Across diverse international settings, prevalence estimates varied widely amongst differing clinical contexts, methodologies, and diagnostic criteria. Although Jessen and colleagues' ( 4 , 7 ) criteria for SCD were the most cited, a minority of studies operationalised them fully; only three studies citing these criteria explicitly excluded patients with pseudodementia. The slightly lower proportion of memory clinic patients we identified as having FCD/SCD relative to the previous review is probably explained by their inclusion of pseudodementia. National differences in service configurations are also likely to be a major source of heterogeneity. Conclusion One in ten people presenting to memory services are diagnosed with SCD and fewer are diagnosed with FCD. 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International Journal of Geriatric Psychiatry [Internet]. 2020 Nov; Available from: https://www.ncbi.nlm.nih.gov/pubmed/32608171 Demnitz-King H. The APPLE-Tree (Active Prevention in People at risk of dementia through Lifestyle, bEhaviour change and Technology to build REsiliEnce) remote, lower-intensity multidomain lifestyle intervention for subjective cognitive decline or MCI: randomised controlled trial”. Baker LD, Espeland MA, Whitmer RA, Snyder HM, Leng X, Lovato L, et al. Structured vs Self-Guided Multidomain Lifestyle Interventions for Global Cognitive Function: The US POINTER Randomized Clinical Trial. JAMA [Internet]. 2025 July 28 [cited 2025 July 29]; Available from: https://doi.org/10.1001/jama.2025.12923 Additional Declarations The authors declare no competing interests. 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1","display":"","copyAsset":false,"role":"figure","size":223632,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend\u0026nbsp;\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8165369/v1/2d17c43a1a5d944615aae4bc.png"},{"id":96913159,"identity":"0c362d03-c334-4f74-b049-88f534d8940a","added_by":"auto","created_at":"2025-11-27 13:53:50","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1013046,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8165369/v1/eeb175b3-c2b8-497e-80cf-cbb7f8a97140.pdf"},{"id":96605776,"identity":"a3610f15-b8ae-4bbd-b25b-c4159cc29026","added_by":"auto","created_at":"2025-11-24 09:24:02","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":134806,"visible":true,"origin":"","legend":"","description":"","filename":"DeNPRUQMProject13supplementarymaterial.docx","url":"https://assets-eu.researchsquare.com/files/rs-8165369/v1/5201e1f1c31484eb962ad4c1.docx"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003eDeNPRU-QM Responsive project: Prevalence of memory complaints in the absence of objective symptoms in clinical populations: systematic review update\u003c/p\u003e","fulltext":[{"header":"Key message ","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eWhat is already known on this topic\u003c/em\u003e\u003c/strong\u003e\u003cem\u003e\u003cbr\u003e\u003c/em\u003eCurrent pathways for assessment and treatment of memory disorders are designed for people with dementia but are also accessed by people with subjective cognitive decline without objective deficits (SCD), or with cognitive deficits likely to be of psychological causation without neurodegeneration (Functional Cognitive Disorders, FCDs).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eWhat this study adds\u003c/em\u003e\u003c/strong\u003e\u003cem\u003e\u003cbr\u003e\u003c/em\u003eThis study updated a systematic review, identifying recent evidence for the prevalence of SCD or FCD among people presenting to any clinical setting, to inform the development of treatment pathways for people presenting with these symptoms. At least 10% of people presenting to memory services are diagnosed with SCD and fewer are diagnosed with FCD. We need consistent guidelines about how these conditions are defined and diagnosed. An integrated, multidisciplinary, neighbourhood health service would be well positioned to treat these groups.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eHow this study might affect research, practice or policy\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cem\u003e\u003cbr\u003e\u003c/em\u003eIdentifying the prevalence of SCD/FCD within specific healthcare settings may inform effective treatment pathways, improving support and care quality. Investing in integrated, community older people\u0026rsquo;s mental and physical health and care services would build capacity to provide effective alternative treatment pathways for those presenting with SCD/FCD symptoms in primary care.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"BACKGROUND","content":"\u003cp\u003eIncreasing numbers of individuals, concerned they have reduced cognitive function, are approaching health services (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). While current pathways for assessment and treatment of memory disorders are designed for people with dementia, they are also accessed by people without objective cognitive deficits, or with deficits of psychological, rather than neurodegenerative causation. Arguably, these groups may be better served by different service models.\u003c/p\u003e\u003cp\u003eAround a third of the general adult population experience subjective cognitive complaints without objective deficits (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). The term subjective cognitive decline (SCD) was conceived in 2014 to describe cognitive symptoms that are too mild to be evident on objective testing (or undetectable in those with high premorbid cognition, due to ceiling effects of current instruments) (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). Its management is often based on a model that places SCD \u0026ldquo;within the realm of degenerative brain disease and at the start of a linear trajectory towards dementia\u0026rdquo;(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). A recent review reported an association between SCD and a two-fold increased risk of developing either mild cognitive impairment (MCI) or dementia (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). However, other studies indicate that while most people who develop Alzheimer\u0026rsquo;s disease and other degenerative dementias experience SCD at some time, most individuals with SCD will not show progressive cognitive decline (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eCognitive symptoms have multiple causes, including functional cognitive disorders (FCDs), drug effects, systemic illness, brain injury, non-degenerative and degenerative brain disease (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). FCDs cause distress or functional impairment and are defined as the presence of symptom(s) of impaired cognitive function, which can be inconsistent between different situations or with observed or measured function, not better explained by another medical disorder (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). A FCD diagnosis infers a specific aetiology of cognitive symptoms (functional and non-neurodegenerative), and poses a diagnostic challenge due to its resemblance to neurocognitive disorders (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). The term FCD conceptualises the cognitive symptoms as psychogenic, relating to the somatisation of distress or worry, as opposed to symptoms occurring within a psychiatric disorder such as anxiety or depression (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). A 2023 systematic review aimed to identify diagnostic symptoms and signs that discriminate it from neurodegeneration. Patients with FCD were younger, more educated, and more often had a family history of older onset dementia. They also had abrupt symptom onset, anxiety, depression and sleep disturbance. Attending appointments alone and bringing a handwritten list of problems predicted FCD (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eBoth FCD and SCD pose diagnostic challenges: FCD due to its resemblance to neurocognitive disorders (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e), and SCD relating to the consistency by which it is defined and therefore the accuracy by which it can predict later neurodegeneration (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). Consequently, identification of SCD and FCD are not straightforward and there is uncertainty for both patient and clinician regarding appropriate symptom management. The English Department of Health and Social Care (DHSC) and NHS England commissioned this review, as part of a wider project to explore how treatment pathways for people presenting with these symptoms might be enhanced.\u003c/p\u003e\u003cp\u003eA 2019 systematic review examining the prevalence of cognitive complaints in the absence of degenerative brain disease found that approximately a quarter of patients presenting to memory clinics received diagnoses suggestive of subjective cognitive impairment, pseudodementia, or FCD. Across 32 studies, these diagnoses were reported in 2,832/12,003 (24%) patients (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). We aimed to update this review by identifying recent evidence for the prevalence of SCD or FCD among people presenting to any clinical setting.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eSearch strategy and selection criteria\u003c/h2\u003e\u003cp\u003eWe searched published, peer-reviewed, English-language literature in MEDLINE, Embase, and PsycINFO databases from 1 March 2019 to 31 May 2025. Search terms for FCD/SCD were informed by the DeNPRU-QM memory service survey and previous reviews (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e), combining condition- and population-specific terms with the Boolean operators \u0026lsquo;AND\u0026rsquo; (between concepts) and \u0026lsquo;OR\u0026rsquo; (within concepts). Reference lists of included studies and relevant reviews were screened (see Table\u0026nbsp;1S, supplementary material for search strategy).\u003c/p\u003e\u003cp\u003eWe included quantitative, observational studies reporting cross-sectional data on prevalence of patients with SCD or FCD, as defined above \u0026ndash; however termed \u0026ndash; among those assessed for possible cognitive disorders in healthcare settings. Eligible studies recruited more than 45 participants (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e) and enrolled patients consecutively referred to or attending a clinical setting over a defined period, thereby drawing from a potentially representative sample of the target population. We excluded studies with SCD samples inclusive of patients with objective cognitive impairment due to neurodegenerative disease (e.g., mild cognitive impairment [MCI]) or related to brain injury, studies that have been retracted by journals, case series, dissertations and meeting abstracts.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eQuality appraisal\u003c/h3\u003e\n\u003cp\u003eWe assessed risk of bias using the RoB-PrevMH tool (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). Two researchers (MM and JS) independently rated each study on clarity of target population definition, and three risk of bias domains related to: sampling; non-response; and information bias. Conflicts were resolved through discussion with a third author (CC). Overall, study quality was judged as \u0026lsquo;high\u0026rsquo; (low risk across all domains), \u0026lsquo;moderate\u0026rsquo; (any unclear risk), or \u0026lsquo;low\u0026rsquo; (any high risk).\u003c/p\u003e\n\u003ch3\u003eData synthesis and analysis\u003c/h3\u003e\n\u003cp\u003eWe conducted an Egger\u0026rsquo;s test to assess risk of publication bias and used the \u0026ldquo;metafunnel\u0026rdquo; package in Stata to produce a funnel plot of effect size against standard error. We reported pooled mean age and standard deviations (SD), proportions of female participants across all included studies, and ethnicity where possible. Where studies reported median age (see Table\u0026nbsp;2S, 3S, and 4S, supplementary material for extracted data), we used these averages to approximate mean (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e), providing pooled estimates using mean age only as a sensitivity analysis.\u003c/p\u003e\u003cp\u003eWe narratively synthesised findings, reporting prevalence of SCD, FCD and related concepts. Using the methods adopted by the previous review we were updating (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e), we divided the number of patients with SCD or FCD by the sample sizes in clinically relevant groups, reporting pooled prevalence estimates, sample sizes and pooled mean age, SDs, and proportions of female participants.\u003c/p\u003e\u003cp\u003eWe performed sensitivity analyses to assess the stability of our findings, including random-effects prevalence meta-analysis models (reporting heterogeneity using I\u003csup\u003e2\u003c/sup\u003e) where subgroup prevalence estimates were pooled (see the Appendix, supplementary material). These meta-analysis models use the inverse of the variance adjusted for between-study heterogeneity (tau-squared), thereby reducing sample size influence. They are based on Freeman-Tukey transformations, stabilising variance and reducing skewness, which were back-transformed to find prevalence estimates.\u003c/p\u003e"},{"header":"FINDINGS","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003eSearch results\u003c/h2\u003e\u003cp\u003eWe identified 743 studies, of which 21 met our inclusion criteria (see Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e for our search results and selection process).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eStudy quality\u003c/h2\u003e\u003cp\u003eThere was high agreement between raters regarding study overall risk of bias (64/84; 76.2%). Most studies were rated moderate quality (16/21; 76.2%), primarily because they did not report sample sizes before applying exclusion criteria or obtaining consent (14/16; 87.5%). No studies had more than one RoB-PrevMH domain rated as \u0026lsquo;unclear\u0026rsquo;. The remaining studies (5/21; 23.8%) were rated high quality (see Table\u0026nbsp;5S, supplementary material).\u003c/p\u003e\u003cp\u003eOver half of the included studies (13; 61.9%) reported prevalence estimates for diagnostic categories defined through standardised clinical assessment (number of studies [\u003cem\u003ek\u003c/em\u003e]\u0026thinsp;=\u0026thinsp;10) or use of questionnaires \u003cem\u003e(k\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3) in prospectively collected data. The remaining 8 studies (38.1%) used existing databases or clinical registers, reporting diagnoses determined in routine clinical practice.\u003c/p\u003e\u003cp\u003eEgger\u0026rsquo;s test for all included studies indicated strong evidence for publication bias (β\u0026thinsp;=\u0026thinsp;13.87; [95% CI: 4.73, 23.01], p\u0026thinsp;=\u0026thinsp;0.005); with smaller studies that reported higher rather than lower prevalence estimates more likely to be published (see Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eS, supplementary material).\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003ePopulation characteristics\u003c/h3\u003e\n\u003cp\u003eThe included studies were conducted in: Europe (9; 42.9%) (including two UK studies); North America (5; 23.8%); Asia (3; 14.3%); South America (3; 14.3%); and Australia (1; 4.8%). The weighted pooled mean age across all studies (\u003cem\u003eN\u003c/em\u003e\u0026thinsp;=\u0026thinsp;12,785) was 73.3 years (SD\u0026thinsp;=\u0026thinsp;7.0) and 55.1% (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7,048) were female. Only five studies reported ethnicity (three were high-quality), so these are reported individually (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eDefinitions/concepts delineating groups with subjective cognitive decline\u003c/h3\u003e\n\u003cp\u003eAlmost all studies reported the prevalence of concepts variously described as subjective (cognitive or memory) decline, impairment or concerns. 8/21 (38.1%) studies used the term \u0026ldquo;subjective cognitive decline\u0026rdquo; (SCD), 6 (28.6%) used \u0026ldquo;subjective cognitive impairment\u0026rdquo; (SCI), 4 (19.1%) used \u0026ldquo;subjective memory complaints\u0026rdquo; (SMC), and 3 (14.3%) used \u0026ldquo;subjective cognitive complaints\u0026rdquo; (SCC). Table\u0026nbsp;6S (supplementary material) shows how frequently terms were used, and how cases were ascertained.\u003c/p\u003e\u003cp\u003eDefinitions of subjective concerns were commonly based on criteria defined by ICD-10, or those delineated by Jessen and colleagues: normal performance on standardised cognitive tests and persistent self-experience of cognitive decline unrelated to an acute event that cannot be explained by objective cognitive impairment (e.g., dementia, MCI) or psychiatric or neurological disease (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e).\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eDefinitions of functional cognitive decline/ impairment\u003c/h2\u003e\u003cp\u003e3/21 (14.3%) studies reported the prevalence of FCD or functional cognitive impairment (FCI). Two studies defined FCD using Ball and colleagues\u0026rsquo; criteria (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e): one or more symptoms of cognitive impairment, evidence of inconsistency between the complaint and clinical assessment, and symptoms of cognitive impairment not explained by other conditions that affect daily functioning or require clinical attention (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). One of these studies included people with SCD and psychiatric disorder within their definition of FCD (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e). The third study used memory clinic assessment to categorise their sample, distinguishing between those with and without objective cognitive decline and then further defining those with FCI (memory complaints without relevant neuropathology due to mental and physical health problems) (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eReported diagnoses\u003c/h2\u003e\u003cp\u003eAfter pooling the samples from all studies reporting SCD prevalence (\u003cem\u003ek\u003c/em\u003e\u0026thinsp;=\u0026thinsp;20; \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;13,155), the most common diagnosis was dementia (39.9%), followed by MCI (25.6%), SCD (17.3%), and \u0026lsquo;other\u0026rsquo; conditions (including FCD; 17.2%). Among the studies reporting FCD prevalence (\u003cem\u003ek\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3; \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4,551) the most common diagnosis was dementia (61.0%), followed by MCI (15.2%), \u0026lsquo;other\u0026rsquo; conditions (including SCD; 18.2%), and FCD (5.6%).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003ePatients presenting to primary care settings with cognitive concerns\u003c/h2\u003e\u003cp\u003eTwo studies evaluated patients presenting to primary care with SCD (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). One (high-quality) study prospectively recruited 91/432 (21.1%) patients who presented to a Basic Health Unit in Brazil over a 6-month period (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). Patients were excluded from formal assessment if they were aged\u0026thinsp;\u0026lt;\u0026thinsp;50 years (n\u0026thinsp;=\u0026thinsp;157) or presented without cognitive concerns (n\u0026thinsp;=\u0026thinsp;167). 15 (16.5%) patients presenting with cognitive concerns were reported to meet Jessen and colleagues\u0026rsquo; SCD criteria (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). A second, (moderate-quality) study analysed clinical data from two cohorts from 17 primary care centres in Sweden (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). Patients aged\u0026thinsp;\u0026ge;\u0026thinsp;40 years undergoing investigation for dementia were recruited for the BioFINDER Primary Care Study (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e). 140/515 (27.2%) had SCD, excluding those with psychiatric disorders.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003ePatients referred to secondary care outpatient settings for diagnostic assessment of cognitive concerns\u003c/h2\u003e\u003cp\u003eSixteen studies recruited from diagnostic memory disorders services. These neurology- (\u003cem\u003ek\u003c/em\u003e\u0026thinsp;=\u0026thinsp;11), psychiatry- (\u003cem\u003ek\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2), geriatric- (\u003cem\u003ek\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2), and multidisciplinary-led (\u003cem\u003ek\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1) services were based in secondary (\u003cem\u003ek\u003c/em\u003e\u0026thinsp;=\u0026thinsp;11) and tertiary (\u003cem\u003ek\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5) case settings. 10 (62.5%) studies reported existing diagnoses, while 6 (37.5%) recruited prospective samples, determining diagnoses through clinical assessments. Two studies were based in memory clinics in the UK (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e) and Finland (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e) dedicated to evaluation of early onset memory problems.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003eHigh quality studies (k\u0026thinsp;=\u0026thinsp;5)\u003c/h2\u003e\u003cp\u003eThree high-quality studies explicitly excluded those with psychiatric disorders from SCD samples in line with Jessen (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e) and Ball (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e) criteria. The UK-based study set in an early onset memory clinic prospectively recruited 348 patients (aged 38\u0026ndash;66) referred over 2.5 years; 220 (63.2%) were White British and 128 (36.8%) from minority ethnic backgrounds. 900/1,200 referrals were deemed inappropriate using published diagnostic guidelines (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e). Referrals were from primary (88.2%) and secondary care services (21.8%). 130 (37.4%) patients had \u0026lsquo;memory complaints without relevant neuropathy\u0026rsquo; and 93 (26.7%) had FCI; others were diagnosed with dementia or MCI (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e). Two USA-based studies, set in a Texan memory disorder clinic, used retrospective data. One recruited consecutive referrals over 6-years, the second over seven years. The former study excluded 116/1,256 not completing assessments (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e). The remaining sample included 161/1,140 (14.1%) patients with SCC. The latter study included 209/1,659 (12.6%) patients with SCC (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). Both studies reported ethnicity, with the former study including 86% Caucasian, 6% African American, 4% Hispanic, and 4% other ethnicity, and the latter study very similar proportions.\u003c/p\u003e\u003cp\u003eA Swedish study prospectively recruited all referrals to a geriatric-led memory clinic over one year. They reported 68/106 (64.2%) had SCI (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e), not excluding those with psychiatric illness.\u003c/p\u003e\u003cp\u003eOnly one high quality memory service-based study evaluated the prevalence of FCD according to Ball\u0026rsquo;s criteria (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e); they included SCD diagnoses in this group according to Jessen and colleagues (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). The service was a neurology-led tertiary memory clinic in Brazil, and prevalence of FCD and SCD was reported. Their sample included 146/496 (29.4%) patients with FCD; 53/146 (36.6%) were SCD diagnoses and 93/146 (63.7%) were psychiatric disorder diagnoses. The authors note that the sample was less highly educated than populations in most epidemiological studies in high income countries (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003ch2\u003eModerate quality studies (k\u0026thinsp;=\u0026thinsp;11)\u003c/h2\u003e\u003cp\u003eA UK-based study asked 85 memory clinics to each audit the case-notes of 50 consecutive patients (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e), and found that 44/3,707 (1.2%) and 16/3,707 (0.4%) of patients had SCD and FCD respectively. Of their sample, 274 (7.4%) belonged to ethnically minoritised groups, including Black, Asian, and other backgrounds. Three studies were based in Sweden. One analysed secondary data from the BioFINDER study 2 (\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e), (discussed above as it also recruited in primary care), finding that 139/698 (19.9%) patients met criteria for SCD (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). A second Swedish study prospectively recruited patients from nine multidisciplinary-led memory clinics (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e); 104/835 (12.5%) patients with diagnoses had SCI. In the third Swedish study, participants were retrospectively sampled from a hospital electronic database and biobank for clinical research (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e); 214/410 (52.2%) patients were SCI cases. A Finnish study (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e) consecutively recruited memory clinic attendees younger than 65 years; 14/210 (6.7%) met SCD criteria.\u003c/p\u003e\u003cp\u003eTwo studies recruited from Greek memory clinics over different time-periods; one included 44/145 (30.3%) patients with SMC (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e), the other 34/174 (19.5%) patients with SCD, for which deterioration of cognitive performance on a range of neuropsychological tests was under 10.0% (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e). Two Canada-based studies used secondary data from the Rural and Remote Memory Clinic, from different time periods; one included 85/149 (57.0%) (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e), the other 95/416 (22.8%) patients with SCI (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). An Australian-based study included 40/129 (31.0%) patients with SCD from the ISLAND clinic (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). Finally, a Taiwanese study retrospectively reported 53 (7.3%) SCD cases in a tertiary memory clinic sample of 727 (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\u003ch2\u003eSummary of memory clinic studies\u003c/h2\u003e\u003cp\u003eIn high-quality studies of memory clinic populations that excluded or identified patients with cognitive symptoms related to comorbid psychiatric illness (\u003cem\u003ek\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3; \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2,347; mean age: 71.6; SD\u0026thinsp;=\u0026thinsp;8.8; 54.4% female), 11.4% (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3,295; 10.2\u0026ndash;14.1%) of participants met SCD criteria (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). In high quality studies where concept criteria (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e) were not fully operationalised (symptoms related to other medical disorders were not excluded), SCD prevalence higher (64.2%) (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e) and FCD prevalence (including both SCD and psychiatric disorder diagnoses) was 29.4% (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eTwo studies that recruited participants from memory clinics for people with early onset memory concerns, reported conflicting findings. In a UK study, 37.4% patients had \u0026lsquo;memory complaints without relevant neuropathy\u0026rsquo; and 93 (26.7%) had FCI (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e), but in a Finnish study only 14 (6.7%) had SCD, with MCI related to non-neurodegenerative causes the most frequent diagnosis (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). This variation may relate to operational or diagnostic differences between the services or studies; the Finnish study used full neuropsychological assessment to detect objective impairment, which may account for the higher proportion with MCI, relative to the UK study which used primary care screening tools.\u003c/p\u003e\u003cp\u003eOnly two studies, both from the UK, reported the prevalence of FCD/FCI amongst patients attending memory clinics (defined in line with Ball and colleagues\u0026rsquo; (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e) criteria); 0.4% FCD was found in a moderate-quality study auditing diagnoses across 85 UK memory clinic populations, and 26.7% FCI in a high-quality, prospective study evaluating patients referred to a young-onset memory clinic.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec18\" class=\"Section2\"\u003e\u003ch2\u003eOther secondary care populations (k\u0026thinsp;=\u0026thinsp;4)\u003c/h2\u003e\u003cp\u003eFour moderate-quality studies described secondary care populations, for whom diagnostic evaluation of cognitive symptoms was not the primary reason for referral. One USA, moderate-quality study, recruited African American adults (mean age: 52.5; SD\u0026thinsp;=\u0026thinsp;10.5; 86% female) attending a post-acute covid clinic, an average of 5 months after covid-infection (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e). 4/87 (4.6%) participants had SCC, defined using scores on the Patient Reported Outcomes Measurement Information System Cognitive Function-Concerns (PROMIS-CF) short form questionnaire.\u003c/p\u003e\u003cp\u003eThe remaining three studies described populations referred for geriatric comprehensive evaluation or rehabilitation. Two used clinically assessed diagnoses to define their study groups (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e). One reviewed secondary data from patients presenting to a neurology clinic in Peru for cognitive evaluation. 330/720 (45.8%) included patients met SCD criteria (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e). The second study prospectively recruited patients presenting with cognitive symptoms to two rehabilitation outpatient clinics in China. Their sample (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;95), excluding those with clinical depression, included 34 (35.8%) patients with SCD (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e). The latter study recruited patients presenting to geriatric outpatient clinics in Turkey (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e). In their final sample (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;794), 313 (48.0%) reported SMC; defined as a positive answer to a question about whether memory concerns affect everyday life.\u003c/p\u003e\u003cp\u003eOverall, among moderate-quality studies of populations presenting to secondary care geriatric comprehensive evaluation or rehabilitation services (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1,467; mean age: 71.6 years [SD\u0026thinsp;=\u0026thinsp;5.7]; 54.9% female), the pooled prevalence of SCD was 42.1% (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1,609; 35.8\u0026ndash;45.8%) (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e), and among a younger population attending a post-acute covid clinic, 4.6% met SCC criteria (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThere has been a considerable volume of research regarding the prevalence of SCD/FCD since a previous review found that a quarter of those referred for cognitive assessments met criteria for FCD, SCI or pseudodementia (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). We found that in high quality studies, one in ten people presenting to memory services meet criteria for SCD and fewer are diagnosed with FCD.\u003c/p\u003e\u003cp\u003eEvidence from UK settings is limited. One higher quality study reported that a quarter of patients referred to a UK young-onset memory clinic had FCD. This is in line with a previous review indicating that FCD is more prevalent among those assessed for dementia at a younger age (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). A second UK study audited current diagnoses and found rates of FCD and SCD much lower than those reported in international, prospective studies. This might be explained by different national service models: the UK system, with access to memory services almost entirely via primary care is more heavily gate-kept than other systems. It might also reflect a lack of consistency in how these conditions are defined and diagnosed.\u003c/p\u003e\u003cp\u003eTools to triage patients without objective cognitive impairment from primary care away from memory clinics have been considered, including digital cognitive tests (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e), biomarkers (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e) and a checklist to identify those more likely to have FCD (\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e). But people with SCD and FCD may both benefit from being seen in a memory clinic for reassurance, and treatment of non-neurodegenerative aetiology. Even if tools were available to accurately triage these groups out of memory services, this would risk reducing the service afforded to these groups, unless alternative, more appropriate pathways for the specific needs of these distinct conditions could be developed. While biomarkers are anticipated to transform the accuracy of dementia diagnostic processes, they are currently only recommended where an objective cognitive deficit likely related to Alzheimer\u0026rsquo;s disease is suspected; a positive biomarker test of uncertain relevance could considerably exacerbate distress.\u003c/p\u003e\u003cp\u003eThe terms FCD and SCD imply causation (degenerative and psychological respectively), which can be problematic as true causation is often unclear and/or complex. Systematic evaluation of the causes of symptoms \u0026ndash; which may include drug effects, physical and psychological illnesses is key to evidence-based treatment. We found that rates of SCD/FCD were higher in studies where psychological disorders as a cause of symptoms were not systematically excluded, suggesting that they may be contributing to many cases.\u003c/p\u003e\u003cp\u003eOlder people are least likely to receive psychological (\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e) and drug treatments (\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e) for mental disorders. Investing in older people\u0026rsquo;s mental health services would build capacity to provide effective alternative treatment pathways for those presenting with SCD/FCD symptoms in primary care. The UK 10-year health plan focus on neighbourhood-based, integrated care will bring together interdisciplinary expertise across geriatrics, primary care, neurology and psychiatry. This integrated workforce would be well positioned, if suitably skilled and resourced, to deliver the joined-up approach to care this patient group needs (\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e). This more integrated approach enables a more holistic, iterative consideration of symptoms, more suited to the needs of these groups. This approach could reduce distress associated with a diagnostic process often culminating in no practical help (\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e), deliver more effective, relevant care for this group who are at low risk of developing dementia, and save resources. The integration of health and social care will be critical too. Providing supportive cognitive wellbeing groups for people with SCD and MCI appears to improve cognition, at relatively low cost (\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e).\u003c/p\u003e\u003cdiv id=\"Sec20\" class=\"Section2\"\u003e\u003ch2\u003eLimitations\u003c/h2\u003e\u003cp\u003eAcross diverse international settings, prevalence estimates varied widely amongst differing clinical contexts, methodologies, and diagnostic criteria. Although Jessen and colleagues' (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e) criteria for SCD were the most cited, a minority of studies operationalised them fully; only three studies citing these criteria explicitly excluded patients with pseudodementia. The slightly lower proportion of memory clinic patients we identified as having FCD/SCD relative to the previous review is probably explained by their inclusion of pseudodementia. National differences in service configurations are also likely to be a major source of heterogeneity.\u003c/p\u003e\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eOne in ten people presenting to memory services are diagnosed with SCD and fewer are diagnosed with FCD. We need consistent guidelines about how these conditions are defined and diagnosed. An integrated, multidisciplinary, neighbourhood health service would be well positioned to treat these groups.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;This research is funded through the NIHR Policy Research Unit in Dementia and Neurodegeneration \u0026ndash; Queen Mary University of London, reference NIHR206110. The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eConflicting interests\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNone known.\u003c/p\u003e\n"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eKelsey O, Demnitz-King H, Kenten C, Chapman H, Muralidhar M, Camboe E, et al. A national survey of dementia diagnosis and care in English memory services [Internet]. Research Square; 2025 [cited 2025 May 2]. Available from: https://www.researchsquare.com/article/rs-6322268/v1\u003c/li\u003e\n\u003cli\u003eMcWhirter L, Ritchie C, Stone J, Carson A. Functional cognitive disorders: a systematic review. Lancet Psychiatry. 2020 Feb;7(2):191\u0026ndash;207. \u003c/li\u003e\n\u003cli\u003eCooper C, Bebbington P, Lindesay J, Meltzer H, McManus S, Jenkins R, et al. 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Frequency and correlates of subjective cognitive complaints and objective cognitive screening results in African American adults following COVID-19 infection. Brain, Behavior, \u0026amp; Immunity - Health. 2023 Dec;34:100691. \u003c/li\u003e\n\u003cli\u003eXu Y, Lin Y, Yi L, Li Z, Li X, Yu Y, et al. Screening for Cognitive Frailty Using Short Cognitive Screening Instruments: Comparison of the Chinese Versions of the MoCA and Qmci Screen. Front Psychol. 2020 Apr 3;11:558. \u003c/li\u003e\n\u003cli\u003eYavuz Veizi BG, Oğuz EO, Ilkin Naharci M. Subjective Memory Complaints in Older Adults: The Role of Polypharmacy and Anticholinergic Burden. J Geriatr Psychiatry Neurol. 2025 May;08919887251339837. \u003c/li\u003e\n\u003cli\u003ePalmqvist S, Hansson O. The Swedish BioFINDER - Primary Care Study [Internet]. 2025. Available from: https://www.clinicaltrials.gov/study/NCT06120361?id=NCT06120361\u003c/li\u003e\n\u003cli\u003eYoung Dementia Network. Diagnosing dementia in younger people. A decision-making guideline [Internet]. Available from: https://www.youngdementianetwork.org/wp-content/uploads/2021/04/YDN_GP_Guide_Leaflet_DL_2021-v5.pdf\u003c/li\u003e\n\u003cli\u003eHansson O, Stomrud. The Swedish BioFINDER 2 Study [Internet]. 2025. Available from: https://www.clinicaltrials.gov/study/NCT03174938?id=NCT03174938\u003c/li\u003e\n\u003cli\u003eCabreira V, Alty J, Antic S, Araujo R, Aybek S, Ball HA, et al. Development of a diagnostic checklist to identify functional cognitive disorder versus other neurocognitive disorders. BMJ Neurol Open. 2025 Feb;7(1):e000918. \u003c/li\u003e\n\u003cli\u003eCooper C, Bebbington P, McManus S, Meltzer H, Stewart R, Farrell M, et al. The treatment of Common Mental Disorders across age groups: results from the 2007 Adult Psychiatric Morbidity Survey. J Affect Disord. 2010 Dec;127(1\u0026ndash;3):96\u0026ndash;101. \u003c/li\u003e\n\u003cli\u003eLarsen AJ, Teobaldi G, Espinoza Jeraldo RI, Falkai P, Cooper C. Effectiveness of pharmacological and non-pharmacological interventions for treatment-resistant depression in older patients: a systematic review and meta-analysis. BMJ Ment Health. 2025 Mar;28(1):e301324. \u003c/li\u003e\n\u003cli\u003eGOV.UK [Internet]. 2025 [cited 2025 May 2]. Build an NHS Fit For the Future. Available from: https://www.gov.uk/missions/nhs\u003c/li\u003e\n\u003cli\u003eCarter C, James T, Higgs P, Cooper C, Rapaport P. Understanding the subjective experiences of memory concern and MCI diagnosis: A scoping review. Dementia (London). 2023 Feb;22(2):439\u0026ndash;74. \u003c/li\u003e\n\u003cli\u003ePoppe M, Mansour H, Rapaport P, Palomo M, Burton A, Morgan-Trimmer S, et al. \u0026lsquo;Falling through the cracks\u0026rsquo;; Stakeholders\u0026rsquo; views around the concept and diagnosis of mild cognitive impairment and their understanding of dementia prevention. International Journal of Geriatric Psychiatry [Internet]. 2020 Nov; Available from: https://www.ncbi.nlm.nih.gov/pubmed/32608171\u003c/li\u003e\n\u003cli\u003eDemnitz-King H. The APPLE-Tree (Active Prevention in People at risk of dementia through Lifestyle, bEhaviour change and Technology to build REsiliEnce) remote, lower-intensity multidomain lifestyle intervention for subjective cognitive decline or MCI: randomised controlled trial\u0026rdquo;. \u003c/li\u003e\n\u003cli\u003eBaker LD, Espeland MA, Whitmer RA, Snyder HM, Leng X, Lovato L, et al. Structured vs Self-Guided Multidomain Lifestyle Interventions for Global Cognitive Function: The US POINTER Randomized Clinical Trial. JAMA [Internet]. 2025 July 28 [cited 2025 July 29]; Available from: https://doi.org/10.1001/jama.2025.12923\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Queen Mary University of London","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":"dementia, cognitive decline, cognitive impairment, neurocognitive disorders, neurodegenerative diseases","lastPublishedDoi":"10.21203/rs.3.rs-8165369/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8165369/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003e\u0026ndash; Current pathways for assessment and treatment of memory disorders are designed for people with dementia but are also accessed by people with subjective cognitive decline without objective deficits (SCD), or with cognitive deficits likely to be of psychological causation without neurodegeneration (Functional Cognitive Disorders, FCDs). We aimed to identify how frequently adults meeting SCD/FCD criteria, arguably better served by different service models, present to health services.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003e\u0026ndash; Updating a previous review, we searched MEDLINE, Embase, and PsycINFO for studies reporting SCD/FCD prevalence within representative clinical samples, published between 2019 and 2025. We assessed study quality using the RoB-PrevMH tool and synthesised data using similar methods to the previous review.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003e\u0026ndash; We included 5/21 high- and 16/21 moderate-quality studies. The pooled mean age was 73.3 years (Standard Deviation\u0026thinsp;=\u0026thinsp;7.0; N\u0026thinsp;=\u0026thinsp;12,785) and 55.1% of participants were female. Across studies reporting SCD (k\u0026thinsp;=\u0026thinsp;20; n\u0026thinsp;=\u0026thinsp;13,155) and FCD (k\u0026thinsp;=\u0026thinsp;3; n\u0026thinsp;=\u0026thinsp;4,551), pooled prevalences were 17.3% and 5.6% respectively. Most studies (k\u0026thinsp;=\u0026thinsp;11; 52.4%) did not explicitly exclude pseudodementia related to psychiatric illnesses. In high quality studies that did, SCD prevalence was 11.4% (\u003cem\u003ek\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3, n\u0026thinsp;=\u0026thinsp;3,295; 10.2\u0026ndash;14.1%) in memory clinic attendees and 16.5% (\u003cem\u003ek\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1, n\u0026thinsp;=\u0026thinsp;91) among primary care attendees aged 50\u0026thinsp;+\u0026thinsp;presenting with cognitive complaints without pre-existing dementia.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003e\u0026ndash; At least 10% of people presenting to memory services are diagnosed with SCD and fewer with FCD. We need consistent guidelines about how these conditions are defined and diagnosed. An integrated, multidisciplinary, neighbourhood health service would be well positioned to treat these groups.\u003c/p\u003e","manuscriptTitle":"DeNPRU-QM Responsive project: Prevalence of memory complaints in the absence of objective symptoms in clinical populations: systematic review update","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-23 15:53:52","doi":"10.21203/rs.3.rs-8165369/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":"1fdaa0d4-b241-47dc-a02a-ba3ce5dc6640","owner":[],"postedDate":"November 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":58330065,"name":"Psychiatry"}],"tags":[],"updatedAt":"2025-11-23T15:53:52+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-23 15:53:52","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8165369","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8165369","identity":"rs-8165369","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}