Inequality of Adolescents’ Mental Health between 2018 and 2023: Repeated Cross-sectional Evidence from COMPASS

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Bélanger, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6933580/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 The COVID-19 pandemic has disrupted adolescents' lifestyles, negatively impacting their mental health and well-being. To date, few studies have examined the medium- to long-term consequences for adolescents. This study examines the evolution of adolescents’ mental health using data collected between 2018 and 2023 from a population of adolescents living in Quebec, Canada, with a focus on depressive symptoms, anxiety symptoms, and flourishing scores. It also explores whether specific demographic and socioeconomic groups are disproportionately affected. Methods We used data collected as part of the COMPASS study from students attending a cohort of 31 high schools in Quebec (Canada). We conducted a repeated cross-sectional analysis from 2018–2023 involving approximately 13,500 adolescents aged 12–17 years each year. The mental health indicators included the Center for Epidemiologic Studies Depression Scale Revised (CESD-R-10), the Generalized Anxiety Disorder scale (GAD-7), and the Diener Flourishing Scale. Statistical analyses employed techniques adapted from the Foster-Greer-Thorbecke indices, establishing a minimum threshold for optimal mental health. We examined various metrics, including the prevalence of mental health issues; the average gap and inequality gap from the threshold of adolescents reporting depressive symptoms, anxiety symptoms or positive flourishing score; and a measure of mental health inequality inspired by the Gini coefficient. Results The prevalence of depressive symptoms and anxiety symptoms increased during the pandemic, peaking in 2021 and 2022, respectively, before returning close to pre-pandemic levels in 2023. However, flourishing scores continued to decline throughout the study period. Anxiety symptoms show greater inequalities than the other two indicators. Girls, older adolescents, and those from more deprived backgrounds presented poorer mental health, with significant disparities persisting post-pandemic. Gender disparities in mental health have widened both during and after the pandemic. Discussion This study reveals that indicators representing positive and negative constructs of mental health evolve differently over time. While depression and anxiety symptoms gradually returned to prepandemic levels, fewer adolescents reported positive flourishing scores over time, emphasizing the urgency of implementing innovative programs that promote holistic well-being, including having positive relationships, feelings of competence, and meaning and purpose in life. Psychology Pediatrics Epidemiology Mental health Depression Anxiety Flourishing Adolescents Inequalities Vulnerabilities Figures Figure 1 Figure 2 Figure 3 Figure 4 Background The COVID-19 pandemic and its associated disruptions, including restrictions and school closures, significantly altered adolescent lifestyles—reducing social interactions ( 1 , 2 ), decreasing physical activity ( 3 – 9 ), and increasing screen time ( 3 , 6 – 9 ). These lifestyle shifts contributed to both short- and long-term mental health challenges ( 10 – 16 ), particularly in a population already facing a decade-long rise in mental health issues ( 17 – 22 ). Reviews of adolescent mental health during the pandemic underscore a heterogeneous decline ( 10 – 16 ), influenced by local contexts, public health restrictions, and study designs ( 12 – 14 ). Despite ample research on adolescent mental health during the pandemic, studies examining the evolution of mental health trajectories beyond 2022 remain limited ( 23 – 29 ). Recent findings reveal mixed trajectories. In Switzerland, well-being among 14–25-year-olds declined from 2017 to 2022, with improvements in negative indicators only emerging in 2022—though the steepest drop in positive indicators preceded the pandemic ( 29 ). In Iceland, adolescents continued to report high depressive symptoms and reduced well-being two years into the pandemic ( 25 ). In Finland, the prevalence of depressive and anxiety symptoms remained elevated between 2021 and 2023, with a deterioration in mental well-being scores ( 23 ). Girls—especially in lower secondary education—showing increased symptoms of anxiety, while boys reported lower social anxiety ( 23 ). By 2023, over 70% of girls and 30% of boys in Finland reported at least one mental health issue ( 23 ). In the UK, no improvement was observed between spring 2022 and spring 2023 ( 24 ). In the Netherlands, improvements noted in 2022 were reversed in 2023 ( 26 ). These ongoing challenges may stem from the pandemic, pre-existing trends, or greater awareness of mental health ( 26 ), echoing findings that symptoms can persist for years post-trauma ( 30 ) and that loneliness may have long-lasting effects ( 31 ). Vulnerable groups—such as girls ( 10 , 11 , 14 ), older adolescents ( 10 , 11 , 14 ), and youth from disadvantaged backgrounds ( 32 – 34 )—remain at heightened risk, though little is known about their recovery patterns. Mental health encompasses not only the absence of disorders but also a dynamic state of emotional, psychological, and social well-being that supports coping, relationships, and community participation ( 35 , 36 ). Flourishing reflects this optimal state, marked by positive emotions, purpose, personal growth, and strong social relationships ( 35 ). The Diener Flourishing Scale captures these dimensions, offering a broader perspective on personal development ( 37 , 38 ). Including flourishing in mental health research shifts the focus beyond pathology to highlight protective factors that foster resilience and thriving ( 35 ). While well-being declined during the pandemic, its post-pandemic trajectory may be distinct from that of negative mental health indicators, possibly due to the time and stability required to rebuild positive functioning ( 23 , 29 ). Previous studies tend to focus on average symptom scores or prevalence, which, while informative, can mask underlying disparities. For instance, a stable average score may mask increasing disparities if mental health improves for some subgroups while others worsen. Similarly, equal increases in prevalence across subgroups do not necessarily indicate greater inequality. To better capture these dynamics, researchers can use distributional measures, which offer a more nuanced understanding beyond simple averages or proportions ( 39 – 41 ). These types of tools, originating from economics, provide a robust framework to assess not only how many adolescents are struggling, but also the extent of their challenges and how far they are from optimal mental well-being. Despite their significant potential to reveal the concentration and depth of mental health challenges and to determine whether difficulties have become more pronounced or if disparities by sex, age, and socioeconomic status have persisted or widened over time, such methods remain underutilized in public health research. Given the mixed—and in some cases, worsening—trends reported in recent studies, it remains unclear whether adolescent mental health has stabilized, continued to deteriorate, or begun to improve in the aftermath of the COVID-19 pandemic. To address this uncertainty, our study examines recent trends using both negative indicators (self-reported depressive and anxiety symptoms) and a positive indicator (flourishing). We aim to assess whether adolescent mental health has stabilized or improved after 2022, and whether these trajectories differ by demographic and socioeconomic characteristics. We propose two hypotheses. First, we hypothesize that during the COVID-19 pandemic, the prevalence of depressive and anxiety symptoms increased while flourishing decreased, with all three indicators stabilizing after 2022. At the same time, we hypothesized that the Gini index, the average gap, and the average inequality gap increased during the during the COVID-19 pandemic and stabilizing after 2022. Second, we hypothesize that the disparities between sexes, age groups, and levels of material deprivation accentuated during the pandemic and persisted beyond 2022 into the recovery phase. We expect the recovery in prevalence, average gap, and average inequality gap to be slower for girls, older adolescents, and individuals from materially deprived families compared to their counterparts. Methodology Study design and participants We utilized data from the COMPASS study on adolescent health (Cannabis Use, Obesity, Mental Health, Physical Activity, Alcohol Use, Smoking, and Sedentary Behaviour) ( 42 ). COMPASS is a study based on school cohorts. Each year, youth in participating high schools are asked to complete a questionnaire about their lifestyle and behaviors. In the province of Quebec, school surveys have been conducted in partnership with school communities and regional public health departments. For this analysis, data were drawn from students attending a cohort of thirty-one high schools in Quebec (Canada) between 2018 and 2023. The schools were from three administrative regions of Quebec: twenty-three from Capitale-Nationale, six from Saguenay-Lac-Saint-Jean and two from Chaudière-Appalaches. Among these, two were urban private schools, and eleven were rural public schools. The remaining eighteen schools were urban public schools. A repeated cross-sectional design was employed to examine changes over this period. This approach enables comparisons across the pre-pandemic (2018 and 2019), peri-pandemic (2021), and post-pandemic (2022 and 2023) periods, providing insights into how trends evolved over time. The severity of public health measures in Quebec during the COVID-19 pandemic fluctuated across different waves. Between March 2020 and March 2022, the government implemented a range of measures, including lockdowns, school closures, curfews, mandatory mask-wearing, and social distancing protocols ( 43 ) (see Table A1 in the Appendix for more details). Every adolescent attending the participating schools was eligible to participate. An active-information passive-consent parental permission protocol was followed. Parents were informed of the study via email. All participants provided assent. The data collection periods included the spring of 2018 (89.6% response rate), 2019 (92.2% response rate), 2021 (72.9% response rate), 2022 (84.6% response rate), and 2023 (85.3% response rate). An annual average of approximately 13,500 adolescents aged between 12 and 17 years old participated in the COMPASS survey. Data from 2020 were excluded from the main analysis because of a low response rate (37.0%) due to the impact of the COVID-19 pandemic on school-based data collection ( 44 ). In 2018 and 2019, student data were collected via paper-and-pencil surveys that were completed during a classroom period and included entire school samples. Since 2021, surveys have been completed online via Qualtrics XM online survey software (Qualtrics, Provo, UT, USA), require a classroom period, and include entire school samples ( 44 ). Further information on the transition to online questionnaires and the challenges encountered during data collection in 2020 are presented in Reel, Battista, and Leatherdale (2020). Measures Depressive symptoms. Depressive symptoms were measured via the 10-item Center for Epidemiologic Studies Depression Scale Revised (CESD-R-10) ( 45 ). The students were asked 10 questions on how often they experienced each symptom within the last 7 days (e.g., “I felt that everything I did was an effort”). The scores were summed to create a total score ranging from 0 to 30; higher scores indicated greater depressive symptoms. According to past research, a CESD-R-10 score equal to or greater than 10 indicates significant depressive symptoms ( 46 , 47 ). Past studies have validated the CESD-R-10 scale as a reliable measure of depressive symptom severity in adolescents, which has strong internal consistency and test-retest reliability ( 45 , 47 – 50 ). Its validity has been confirmed in both clinical and nonclinical adolescent populations through its ability to distinguish between individuals with and without depression, as well as its strong correlations with clinical diagnoses and other psychological assessments ( 45 , 47 – 50 ). Data from the COMPASS have shown that the CESD scale respects strict measurement invariance according to grade, age and sex ( 51 ). Previously, the COMPASS study consistently reported strong internal reliability, with Cronbach's alpha values exceeding 0.70 across multiple years ( 51 , 52 ). Anxiety symptoms. Anxiety symptoms were reported by participants via the 7-item Generalized Anxiety Disorder Scale (GAD-7) ( 53 ). The students were asked 7 questions on how often they experienced each symptom in the last 2 weeks (e.g., “Not being able to stop or control worrying”). The scores were summed to create a total score ranging from 0 to 21; higher scores indicated greater anxiety symptoms. According to past research, a GAD-7 score smaller than 10 indicates no to mild anxiety symptoms, whereas a score equal to or greater than 10 indicates moderate to severe anxiety symptoms ( 46 , 53 ). In both clinical and nonclinical populations of adults and adolescents, GAD-7 scores show strong correlations with other measures of anxiety and emotional distress ( 53 – 55 ) and exhibit strict measurement invariance across grades, ages, and sex in previous COMPASS data ( 51 ). Previously, COMPASS has demonstrated strong internal reliability, with Cronbach's alpha values exceeding 0.88 across multiple years ( 51 ). Flourishing scale. We measured psychological well-being using an 8-item Flourishing Scale, adapted from Diener ( 37 ). Participants answered 8 questions like "I lead a purposeful and meaningful life" on a 5-point Likert scale (1 = strongly disagree, 5 = strongly agree). Total scores range from 8 to 40, with higher scores indicating greater psychological well-being (encompassing positive relationships, competence, meaning, and purpose). These scores are strongly correlated with other measures of psychological and social well-being ( 56 ). While our 5-point scale differs from Diener's original 7-point Likert scale (scores 8–56) ( 37 ), this adapted version has demonstrated strong internal reliability and measurement invariance within the COMPASS sample ( 38 ), with Cronbach's alpha scores consistently at 0.90 across multiple COMPASS years ( 57 ). The mean flourishing score in this sample, ranging from 31–33, appears lower than lower than averages reported using the original scale (e.g., 44.97 or 42.6–48.1 ( 37 )). However, a mean score of 32 out of 40 on our adapted scale, representing 80% of the maximum possible score, is comparable to a mean of 45 out of 56 on the original scale. This suggests that participants in this study report similar levels of flourishing to those found in other normative populations. Since the Flourishing Scale lacks validated cut-off points, we established a threshold. A score of 30, corresponding to the 20th percentile of the distribution, was selected. The 20th percentile was specifically selected to fall between the pre-pandemic percentiles observed for adolescents with depressive or anxiety symptoms (i.e., a CESD-R-10 score of 10 corresponded to the 25th percentile, and a GAD-7 score of 10 corresponded to the 15th percentile). This exploratory cut-off is practical but should be interpreted with caution. It may reflect the absence of symptoms or positive mental health rather than "optimal" flourishing. Future research is needed to validate this cut-off. Covariates. The participants provided their age and sex. Sex was categorized as either boys or girls. The gender question in the COMPASS was updated in 2021 to include nonbinary options. To ensure consistency with the 2018 and 2019 questionnaires, participants identified as neither male nor female were excluded from the analysis. Family-level material deprivation was assessed via a score based on adolescents’ responses to at least four out of seven questions regarding their living conditions and personal expenses. The questions included 1) the average amount of money they receive weekly for personal spending or savings; 2) skipping breakfast due to a lack of food at home; 3) going to bed hungry because there is not enough money to buy food; 4) perceiving their family as less financially comfortable than the average student in their class; 5) having their own bedroom; 6) the number of people living in their household; and 7) worrying about their family’s ability to pay bills and expenses. The composite scores were then divided into two categories: more deprived and less deprived ( 58 ). Statistical analysis Methods inspired by the Gini coefficient First, we used the Gini coefficient to quantify inequalities in the distribution of mental health outcomes ( 40 ). The Gini coefficient, a measure commonly used in economics to assess income inequality, has also been applied to quantify the distribution of health ( 59 – 61 ). It ranges from 0 (perfect equality, where all individuals have the same mental health outcome) to 1 (complete inequality, where all mental health issues are concentrated in one individual) ( 40 ). In our study, the Gini index was used to measure disparities in mental health outcomes (CESD-R-10, GAD-7, and the Flourishing Scale) among adolescents via Stata 17 ( 62 ) and the ineq command from the Distributive Analysis Stata Package ( 63 ). A higher Gini mental health index indicates wider gaps in these outcomes between individuals. The interpretation of these indices helps highlight whether mental health outcomes are becoming more or less equitable over time. Foster-Greer-Thorbecke (FGT) indices Our study employed statistical methods inspired by poverty analysis techniques adapted for application in health research ( 41 ). These methods focus on identifying unmet need determined by a threshold value. In this case, the threshold values are the scale cut-offs used to assess depressive symptoms (CESD-R-10 score ≥ 10), anxiety symptoms (GAD-7 score ≥ 10), or positive flourishing scores (Flourishing Scale score ≥ 30). Using an adaptation of the FGT indices ( 39 ), we estimated the prevalence, average gap, and average inequality gap in these outcomes using ratio-scale variables (see explanation below). To apply FGT-inspired indices, ratio-scale variables were ordered in ascending value, starting with the group of interest (i.e., adolescents reporting poorer mental health for negative indicators and those reporting flourishing for the Flourishing Scale) and extending to the rest of the sample. To enable this consistent ordering, we reversed the scoring of the CESD-R-10, GAD-7, and Flourishing scales so that lower values corresponded to greater symptom severity or better outcomes for the flourishing score. This was done by subtracting each participant’s raw score from the maximum possible score for each scale (i.e., 30 for CESD-R-10, 21 for GAD-7, and 40 for the Flourishing Scale). For example, a raw CESD-R-10 score of 16 was transformed to an inverted score of 14 (30–16 = 14), where lower scores indicated worse mental health. This transformation allowed us to apply a consistent “shortfall” logic across all indicators. The new thresholds defining unmet need became ≤ 20 for depressive symptoms, ≤ 11 for anxiety symptoms, and ≤ 29 for flourishing, corresponding respectively to the original cut-offs of CESD-R-10 ≥ 10, GAD-7 ≥ 10, and Flourishing Scale ≥ 30. To help interpret these threshold values, histograms of the CESD-R-10, GAD-7, and Flourishing Scale scores are presented in the Appendix (Figure A2, A3, and A4). The prevalence reflects the proportion of adolescents above the thresholds, i.e., reporting depressive symptoms (CESD-R-10 score ≥ 10), anxiety symptoms (GAD-7 score ≥ 10) or positive flourishing score (Flourishing Scale score ≥ 30). It was estimated via adjusted logistic regression with Stata 17’s logit command, generating results with 95% confidence intervals ( 62 ). The average gap quantified the mean deviation from the thresholds. It is calculated as a relative measure of the average mental health gap between the threshold score and the average CESD-R-10 score (≥ 10), GAD-7 score (≥ 10) or positive flourishing score (≥ 30). As the scores are normalized relative to the threshold, the average gap is always bounded between 0 and 1. A greater gap indicates that adolescents are farther from reaching the threshold to not report depressive symptoms, anxiety symptoms, or positive flourishing score. For example, an average gap of 10% indicates that adolescents reporting depressive symptoms are, on average, within 10 percentage points of the threshold for not reporting these symptoms. This provides a relative measure of the effort required for these average adolescents to no longer report depressive symptoms. The average inequality gap reflects the overall magnitude of the disparities. Mathematically, it represents the square of the average gap of everyone below the threshold. As the scores are normalized relative to the threshold, the average inequality gap is always bounded between 0 and 1. The greater the gap is, the further adolescents at the lower end are from the threshold value. For example, a 5% average inequality gap suggests that the adolescents farthest from the threshold value (at the lower end) require 5% more effort than the average adolescent reporting depressive symptoms to stop reporting depressive symptoms. (A visual explanation of the three indices is available in Appendix Figure A1.) The average gap and average inequality gap indices were calculated for each participant. To obtain aggregate values, we used the glm command with a gamma distribution and log link in Stata 17 ( 62 ). To summarize the Foster-Greer-Thorbecke (FGT) framework ( 39 ) we just explained, it allowed us to assess: Prevalence (Headcount): The proportion of individuals below a defined threshold, comparable to prevalence based on a scale cut-off. Average Gap (Depth): The average "distance" participants fall below a threshold (scale cut-off), reflecting the severity of the difficulties within this group. Average Inequality Gap (Severity): The level of inequality among those below a threshold (scale cut-off), indicating how unevenly difficulties are distributed within this group. It's important to note that we adapted these indices to quantify mental health disparities and are not using them to measure socioeconomic poverty. We examined differences between sexes in terms of prevalence and average gap via year × sex interaction terms. Differences between age and between family-level material deprivation were examined (see Tables A8 and A9 and Figures A5, A6, A7, and A8 in the appendix). All analyses considered the clustering of individuals within schools’ robust covariance. They were conducted via Stata 17 ( 62 ), and adjusted results by year were obtained via the margins command ( 64 ). We conducted a complete case analysis (Further information on missing data can be found in tables A5 and A6 in the appendix.) Results Population characteristics As shown in Table 1 , the percentage of boys ranged from 44.5–47.7%, with slight fluctuations over time. The average age remained consistent at approximately 14.5 years. Over the same period, there was a notable increase in the proportion of adolescents classified in the most deprived category of family-level material deprivation, increasing from 23.7% in 2018 to 36.1% in 2023. The average depressive symptoms increased from 7.4 to 8.9, the average anxiety symptoms increased from 5.0 to 6.4, and the average flourishing score decreased from 33.2 to 31.4 during this time frame. Table 1 Characteristics of Quebec adolescents who participated in the COMPASS study (2018–2023) Pre-pandemic Peri-pandemic Post-pandemic 2018 (N = 14,320) 2019 (N = 14,796) 2021 (N = 11,937) 2022 (N = 13,926) 2023 (N = 17,042) Sex Boys 6,829 (47.7%) 7,035 (47.6%) 5,315 (44.5%) 6,387 (45.9%) 8,102 (47.5%) Missing 67 (0.5%) 118 (0.8%) 183 (1.5%) 250 (1.8%) 198 (1.2%) Age Mean (SD) 14.7 (1.6) 14.6 (1.6) 14.5 (1.5) 14.4 (1.5) 14.5 (1.5) Missing 42 (0.3%) 85 (0.6%) 150 (1.3%) 156 (1.1%) 123 (0.7%) Family-level material deprivation More deprived 3,396 (23.7%) 3,396 (23.0%) 3,923 (32.9%) 5,141 (36.9%) 6,157 (36.1%) Missing 0 39 (0.3%) 218 (1.8%) 196 (1.4%) 153 (0.9%) CESD-R-10 ≥ 10 3,365 (23.5%) 4,058 (27.4%) 4,238 (35.5%) 5,087 (36.5%) 5,769 (33.9%) Mean (SD) 7.4 (5.5) 8.1 (5.8) 9.4 (6.5) 9.5 (6.5) 8.9 (6.2) Missing 1,890 (13.2%) 2,061 (13.9%) 1,676 (14.0%) 1,735 (12.5%) 1,577 (9.3%) GAD-7 ≥ 10 2,171 (15.2%) 2,372 (16.0%) 2,709 (22.7%) 3,600 (25.9%) 4,034 (23.7%) Mean (SD) 5.0 (4.8) 5.2 (4.9) 6.4 (5.4) 6.9 (5.7) 6.4 (5.6) Missing 1,231 (8.6%) 1,385 (9.4%) 1,346 (11.3%) 1,327 (9.5%) 1,241 (7.3%) Flourishing scale ≥ 30 10,677 (78.5%) 10,852 (78.0%) 7,712 (71.3%) 8,675 (67.8%) 4,902 (66.0%)* Mean (SD) 33.2 (5.3) 33.1 (5.5) 32.3 (5.9) 31.7 (6.1) 31.4 (6.5)* Missing 721 (5.0%) 874 (5.9%) 1,117 (9.4%) 1,131 (8.1%) 818 (9.9%)* * The questionnaire on flourishing was completed by a total of 8,241 adolescents in 2023. Trends in mental health We observed a decline in adolescents’ mental health during the COVID-19 pandemic (Fig. 1 , part a). Between the peri-pandemic (2021) and post-pandemic (2022) periods, the prevalence of adolescents reporting depressive symptoms stabilized at 41%, whereas anxiety symptoms (28%) and positive flourishing (69%) continued to deteriorate. In the post-pandemic period (2023), we observed lower levels of depressive and anxiety symptoms, with 37% and 25%, respectively. The prevalence of adolescents with positive flourishing decreased to 67%. Figure 1 (part b) illustrates the growth in mental health inequalities from pre- (2019) to peri-pandemic (2021) for the three mental health indicators using methods inspired by the Gini coefficient. This growth persists post-pandemic, reaching 22% for anxiety symptoms in 2022 and 11% for flourishing scores in 2023. This finding indicates that the disparities between individuals continue to widen post-pandemic over the GAD-7 and the Flourishing Scale. However, by 2023, there was a slight decline in inequality for depressive and anxiety symptoms, reaching 16% and 21%, respectively. This finding indicates that the Gini mental health index might slowly return to pre-pandemic levels. This suggests that the distributions of the CESD-R-10 and GAD-7 scores became more uniform, with fewer extreme differences between adolescents. Figure 2 focuses on adolescents reporting depressive symptoms, anxiety symptoms, and positive flourishing scores. This finding shows that adolescents’ mental health has continued to degrade over the years. In 2023, adolescents reported an average gap from the threshold of 31% for depressive symptoms, 44% for anxiety symptoms, and 22% for the positive flourishing score (part a). The situation has improved compared with that in 2021 and 2022 for depressive and anxiety symptoms but remains worse than that in the pre-pandemic period. Moreover, the average adolescent with a positive flourishing score gradually moved closer to the lower flourishing threshold over time. Figure 2 , part b shows only a slight increase in the average inequality gap compared with the pre-pandemic values for depressive symptoms (14%) and the positive flourishing score (10%) in 2023. However, anxiety symptoms rose from 24% in 2018 to 28% in 2023. This finding indicates that adolescents with higher depressive symptoms or positive flourishing scores maintained approximately the same levels over time, whereas those with higher anxiety symptoms became increasingly anxious. Stratification by sex, age, and family-level material deprivation A greater proportion of girls reported depressive symptoms and anxiety symptoms, and fewer reported a positive flourishing score than boys did (Fig. 3 ). We focus here on sex-based differences, as they revealed the largest and most consistent inequalities across all mental health indicators. This sex difference increased over time. Between the pre-pandemic period (2019) and the peri-pandemic period (2021), the prevalence of girls reporting depressive symptoms increased by 11.2 percentage points, reaching 53% in 2021 (Table A7, Fig. 3 ). However, boys experienced an increase of 4.7 percentage points, reaching 26% in 2021 (Table A7, Fig. 3 ). This highlights a growing disparity, as the prevalence of depressive symptoms increased by 6.6 percentage points more for girls than for boys. By 2023, boys had returned to pre-pandemic levels (21%), whereas girls remained 8.5 percentage points above their pre-pandemic prevalence, reflecting a greater overall increase of 8.7 percentage points for girls. A similar pattern was observed for anxiety symptoms. However, unlike depression and anxiety, the proportion of both boys and girls reporting positive flourishing continued to decline over time. The average gap from the threshold of adolescents reporting depressive symptoms, anxiety symptoms or positive flourishing scores presented a comparable trend (Fig. 4 ). The sex difference increased over time. Boys reported an average depressive symptom gap of 26% after the pandemic (2023), which was nearly the same as that reported before the pandemic (2019). However, girls reported an average depressive symptom gap of 33% after the pandemic (2023), an increase of 2.6 percentage points from pre-pandemic levels (2019). No significant difference between sexes was observed for the positive flourishing score. A greater proportion of older adolescents reported depressive symptoms or anxiety symptoms, and a lower proportion of older adolescents reported positive flourishing scores (Figure A5). The prevalence trends were similar for the two age groups (Table A8). The average gap in anxiety symptoms suggests that symptoms became more pronounced among adolescents aged 13 years and younger from pre-pandemic (2019) to post-pandemic (2023), reaching 44%, a level similar to that of adolescents aged 14 years and older (Figure A6). It represented an increase of more than 4.8 percentage points compared with adolescents aged 14 and older (Table A6). (See appendix for figures A5 and A6 and for Table A8.) Stratification by family-level material deprivation indicated that a greater proportion of more deprived adolescents reported depressive symptoms or anxiety symptoms, while fewer reported positive flourishing scores than did their less deprived peers (Figure A7). This difference increased from pre- to post-pandemic values of approximately three percentage points (Table A9). The average gap increased by 4.6 percentage points for anxiety symptoms but decreased by 3.3 percentage points for the positive flourishing score between adolescents from both more and less deprived families over the period (Figure A8, Table A7). This suggests that adolescents from less deprived families are experiencing symptoms more similar to those of adolescents from more deprived families. (See the Appendix for figures A7 and A8 and table A9.) These analyses were conducted across age groups and levels of family material deprivation; while the results are discussed in the main text, the corresponding figures and tables are presented in the Supplement. Discussion This study provides a portrait of adolescents’ mental health trends from 2018 to 2023, using complementary indicators such as the Gini index and three indices derived from the FGT framework: prevalence, average gap from threshold, and average inequality gap. Together, these measures reveal not only how many adolescents are affected, but also how severely and how unequally mental health burdens are distributed across the population. Whereas the FGT inequality gap focuses on disparities among those below a threshold, the Gini index captures inequality across the full distribution of mental health scores, offering a complementary view of concentration. Across all indicators, we observed a marked deterioration in adolescents’ mental health during the COVID-19 pandemic. This decline persisted in 2022, with elevated prevalence rates, more severe symptoms (as reflected by a larger average gap), and increased inequalities (as reflected by a larger average inequality gap) among adolescents experiencing depressive symptoms, anxiety, or positive flourishing. These findings are consistent with prior literature highlighting a pandemic-related surge in psychological distress among youth ( 10 – 16 ). Importantly, our data reveal diverging post-pandemic trajectories across mental health dimensions. While all indices of depressive and anxiety symptoms—prevalence, average gap, and inequality—improved in 2023, suggesting partial recovery and resilience, the flourishing score declined further across these same dimensions. This persistent downward trend in positive mental health, even after the easing of public health restrictions, is particularly concerning. It suggests that while symptoms may have receded, adolescents’ deeper sense of well-being, purpose, and connection remains compromised. This echoes prior work showing that flourishing encompasses broader psychological and social dimensions—such as optimism, meaning in life, and social connectedness—that may be slower to recover ( 37 , 38 ). The combined use of prevalence, average gap, and inequality gap indicators highlights that improvements in average mental health do not necessarily translate into more equitable outcomes. For instance, although the prevalence of depressive symptoms declined between 2022 and 2023, the average gap barely decreased. This suggests that some subgroups of adolescents continue to experience disproportionately high levels of distress—an issue that would remain hidden if only prevalence were considered. The Gini index and FGT-based indices are particularly valuable in this regard, as they capture the extent to which mental health or low flourishing is concentrated among a minority of adolescents. This provides a more equity-sensitive lens that is critical for monitoring population mental health. Beyond population-wide trends, stratified analyses reveal persistent and widening inequalities. Our stratified analyses reinforce this point. Girls, older adolescents, and those from more materially deprived families consistently reported worse mental health outcomes across all three mental health indicators. Notably, sex-based disparities in depressive and anxiety symptoms have widened over time: in 2023, boys largely returned to pre-pandemic levels, while girls remained significantly above their 2019 baselines. This is consistent with research showing that girls and older adolescents are more vulnerable to mental health challenges during crises like the COVID-19 pandemic ( 10 , 11 , 14 ), possibly due to developmental or hormonal factors ( 65 , 66 ). Similarly, adolescents from less materially deprived families experienced greater post-pandemic declines in flourishing and anxiety symptoms than their more deprived peers, narrowing the socioeconomic gap but due to worsening outcomes among advantaged groups rather than improvement among vulnerable ones. This pattern highlights the importance of interpreting convergence in inequalities carefully, as it may mask population-wide declines rather than signal progress toward equity. These findings challenge a narrow interpretation of adolescent recovery. The apparent rebound in symptom prevalence masks persistent disparities and continued erosion of well-being. A holistic understanding of youth mental health post-COVID requires attention not only to the presence or absence of symptoms, but also to broader social and psychological indicators, and how these are distributed across populations. From a public health perspective, this multidimensional decline observed across mental health indicators calls for sustained investment in adolescent well-being—beyond short-term crisis response. Relying solely on prevalence metrics is insufficient. Incorporating measures of severity (average gap) and inequality (inequality gap) provides a more equity-sensitive approach to monitoring and addressing mental health needs. Moreover, flourishing—representing broader dimensions of meaning, optimism, and connection—should be systematically tracked alongside symptoms of distress. Effective responses must combine universal and targeted strategies. Schools, families, and communities should be supported to create protective environments through upstream interventions like social-emotional learning and school-wide mental health promotion ( 67 , 68 ). At the same time, resources must be directed toward the most affected groups, particularly girls, older adolescents, and those experiencing material deprivation ( 69 ). A holistic, equity-oriented approach is essential to rebuild a foundation for long-term youth well-being ( 46 ) ( 70 ). Limitations A few limitations should be mentioned. First, the shift from paper-based questionnaires to online questionnaires may have influenced respondents’ answers. However, the reliability of these scales has remained consistently high. Moreover, a study specifically examining this transition reported measurement invariance in the CESD-R-10 among adolescents ( 52 ). Second, Quebec may have implemented different infection control measures and experienced different stages of the COVID-19 pandemic at various time points than other provinces or countries did. Therefore, our findings may not be broadly applicable to regions beyond Quebec. Moreover, due to the cross-sectional nature of our data and the dynamic nature of the pandemic, we cannot establish causal relationships regarding the impact of the health crisis on adolescents. Numerous cumulative events occurred during this period, making pinpointing specific causes and effects challenging. Therefore, our focus was primarily on tracking the evolving situation after the health crisis and highlighting the changes and challenges faced by adolescents. We excluded data from the spring of 2020 from the main results because of the low participation rates during school closures (before online classes were implemented). For additional information, Table A7 and Figure A9 in the Appendix presents results that include the 2020 data. These supplementary findings should be interpreted with caution, as there may have been a selection bias whereby students who participated may have adapted better to the early pandemic context than those who did not participate in the study. This highlights a common challenge in cross-sectional and longitudinal mental health studies conducted during periods of large-scale disruption. Low response rates and rapidly changing conditions may compromise representativeness and limit comparability across time points. These observations underscore the importance of using strategies designs to promote representativeness across time and to adopt longitudinal designs to capture dynamic changes in adolescent mental health during crises. Conclusion The findings of this school-based repeated cross-sectional study reveal a divergent evolution of positive and negative constructs of mental health in Quebec, Canada, following the COVID-19 pandemic. While negative mental health indicators showed signs of improvement, positive mental health (flourishing) continued to deteriorate. This highlights that simply focusing on symptom reduction is insufficient; a holistic view is important. Our analyses revealed that girls, older adolescents, and those from families experiencing higher levels of material deprivation remain particularly vulnerable to poorer mental health outcomes, with gender disparities widening over time across all three indicators examined. These findings underscore the need for comprehensive mental health assessments that not only reveal how many adolescents are affected, but also how severely and how unequally mental health burdens are distributed across the population. This broader perspective is essential for developing mental health support that not only reduces symptoms but also actively fosters holistic well-being. Strengthening the role of families, schools, and health systems through integrated and inclusive approaches could be pivotal in helping adolescents navigate future challenges and achieve long-term flourishing. Declarations Ethics approval and consent to participate The COMPASS study received ethics approval from the University of Waterloo Office of Research Ethics (ORE#30118) and CIUSSS de la Capitale-Nationale–Université Laval (#MP-13-2017-1264), and all participating school boards. All procedures were conducted in accordance with the ethical standards of the Helsinki Declaration. Informed consent was obtained from participants and from parents/guardians for all children under 16 years of age. Using active-information, passive-consent protocols, parents/guardians of all eligible students were sent study permission information via email and/or automated school phone system a minimum of two weeks prior to the survey start date, with the option to actively withdraw permission for their child(ren) to participate. Students whose parents did not withdraw consent were invited to participate and could decline participation at any time prior to submitting survey responses. Consent for publication Not applicable Availability of data and materials The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request submitted via the following online application form (https://uwaterloo.ca/compass-system/information-researchers). Competing interests The authors declare that they have no competing interests. Funding The COMPASS study has been supported by a bridge grant from the CIHR Institute of Nutrition, Metabolism and Diabetes (INMD) through the “Obesity – Interventions to Prevent or Treat” priority funding award (OOP-110788; awarded to SL), an operating grant from the CIHR Institute of Population and Public Health (CIHR) (MOP-114875; awarded to SL), a CIHR project grant (PJT-148562; awarded to SL), a CIHR bridge grant (PJT-149092; awarded to Karen A. Patte/SL), a CIHR project grant (PJT-159693; awarded to KAP), a research funding arrangement with Health Canada (#1617–HQ-000012; contract awarded to SL), a CIHR-Canadian Centre on Substance Use and Addiction (CCSA) team grant (OF7B1-PCPEGT410-10-9633; awarded to SL), and a project grant from the CIHR Institute of Population and Public Health (IPPH) (PJT-180262; awarded to SL and Karen A. Patte). A SickKids Foundation New Investigator Grant, in partnership with the CIHR Institute of Human Development, Child and Youth Health (IHDCYH) (Grant No. NI21-1193; awarded to Karen A. Patte), funds a mixed methods study examining the impact of the COVID-19 pandemic on youth mental health, leveraging COMPASS study data. The COMPASS Quebec project additionally benefits from funding from the Ministère de la Santé et des Services sociaux of the province of Québec, the Direction régionale de santé publique du CIUSSS de la Capitale-Nationale and the Fonds de recherche du Québec – Society and Culture (FRQSC) (Grant No. 2024-0UER-339082). The study is also supported by a CIHR Operating Grant (#179224). AMTT is supported by the research scholar program from the Fonds de Recherche du Québec–Santé. Authors' contributions The manuscript was conceptualized by KP, SH, and AMTT. Formal analysis and validation were conducted by KP, SH, and AMTT. KP wrote the first draft of the manuscript and created the tables. The draft was reviewed and edited by AMTT, REB, JJCG, RJG, CBD, SH, and STL. The funding acquisition, project administration and investigation were conducted by SH, REB, STL, AMTT, and CBD. All the authors have had full access to all the data in the study and have final responsibility for the decision to submit for publication. Acknowledgments The authors wish to thank the Quebec public health authorities, participating schools, school boards and students as well as the COMPASS team for their significant contributions. References Orben A, Tomova L, Blakemore SJ (2020) The effects of social deprivation on adolescent development and mental health. Lancet Child Adolesc Health 4(8):634–640 Sundler AJ, Bergnehr D, Haffejee S, Iqbal H, Orellana MF, Del Vergara A et al (2023) Adolescents' and young people's experiences of social relationships and health concerns during COVID-19. 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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-6933580","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":473769074,"identity":"7bc88470-111a-421c-b5cc-f14fad664d61","order_by":0,"name":"Krystel Poirier","email":"","orcid":"","institution":"Centre de Recherche VITAM, CIUSSS de la Capitale-Nationale, Québec City, Québec, Canada ; Department of Social and Preventive Medicine, Université Laval, Québec City, Québec, Canada","correspondingAuthor":false,"prefix":"","firstName":"Krystel","middleName":"","lastName":"Poirier","suffix":""},{"id":473769075,"identity":"321790fc-ea85-41f2-806a-4f16f840bfef","order_by":1,"name":"Anne-Marie Turcotte-Tremblay","email":"data:image/png;base64,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","orcid":"","institution":"Centre de Recherche VITAM, CIUSSS de la Capitale-Nationale, Québec City, Québec, Canada ; Faculty of Nursing, Université Laval, Québec City, Québec, Canada","correspondingAuthor":true,"prefix":"","firstName":"Anne-Marie","middleName":"","lastName":"Turcotte-Tremblay","suffix":""},{"id":473769076,"identity":"1f54a06e-d450-4600-a479-4ad8531dcb76","order_by":2,"name":"Richard E. Bélanger","email":"","orcid":"","institution":"Centre de Recherche VITAM, CIUSSS de la Capitale-Nationale, Québec City, Québec, Canada ; Faculty of Medicine, Université Laval, Québec City, Québec, Canada","correspondingAuthor":false,"prefix":"","firstName":"Richard","middleName":"E.","lastName":"Bélanger","suffix":""},{"id":473769077,"identity":"f088d483-1268-4456-be8e-db8657a4ce02","order_by":3,"name":"Jean-Jonathan Cocou Gozo","email":"","orcid":"","institution":"Centre de Recherche VITAM, CIUSSS de la Capitale-Nationale, Québec City, Québec, Canada","correspondingAuthor":false,"prefix":"","firstName":"Jean-Jonathan","middleName":"Cocou","lastName":"Gozo","suffix":""},{"id":473769078,"identity":"2347dcae-73b5-47dd-b0ea-04faf99af55b","order_by":4,"name":"Rabi Joël Gansaonré","email":"","orcid":"","institution":"Centre de Recherche VITAM, CIUSSS de la Capitale-Nationale, Québec City, Québec, Canada","correspondingAuthor":false,"prefix":"","firstName":"Rabi","middleName":"Joël","lastName":"Gansaonré","suffix":""},{"id":473769079,"identity":"21a224c8-38ed-4af7-9df7-74742c8a3186","order_by":5,"name":"Claude Bacque Dion","email":"","orcid":"","institution":"Centre de Recherche VITAM, CIUSSS de la Capitale-Nationale, Québec City, Québec, Canada","correspondingAuthor":false,"prefix":"","firstName":"Claude","middleName":"Bacque","lastName":"Dion","suffix":""},{"id":473769080,"identity":"e0ca433a-57dc-46ee-80b2-4173dbdfd087","order_by":6,"name":"Scott T. Leatherdale","email":"","orcid":"","institution":"School of Public Health Sciences, University of Waterloo, Waterloo, Ontario, Canada","correspondingAuthor":false,"prefix":"","firstName":"Scott","middleName":"T.","lastName":"Leatherdale","suffix":""},{"id":473769081,"identity":"aff01a0a-c022-4cde-9b2b-bf37e1bf4eff","order_by":7,"name":"Slim Haddad","email":"","orcid":"","institution":"Centre de Recherche VITAM, CIUSSS de la Capitale-Nationale, Québec City, Québec, Canada ; Department of Social and Preventive Medicine, Université Laval, Québec City, Québec, Canada","correspondingAuthor":false,"prefix":"","firstName":"Slim","middleName":"","lastName":"Haddad","suffix":""}],"badges":[],"createdAt":"2025-06-19 20:00:31","currentVersionCode":1,"declarations":{"humanSubjects":true,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":true,"humanSubjectConsent":true,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-6933580/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6933580/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":85168848,"identity":"7fc8b2af-1b63-4dd6-93ab-6937c888593c","added_by":"auto","created_at":"2025-06-23 05:00:35","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":45098,"visible":true,"origin":"","legend":"\u003cp\u003eTrends in adolescents’ mental Health: prevalence and inequality (2018–2023)\u003c/p\u003e\n\u003cp\u003e1a Prevalence adjusted for sex, age, and family-level material deprivation.\u003c/p\u003e\n\u003cp\u003e1b Inequality inspired by the Gini coefficient.\u003c/p\u003e\n\u003cp\u003eDepressive symptoms: reverse CESD-R-10 ≤ 20; anxiety symptoms: reverse GAD-7 ≤ 11; or positive flourishing: reverse score ≤ 29.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6933580/v1/555e83a22af89a15e37c6786.png"},{"id":85168851,"identity":"ac0b5816-cc30-4165-931d-a4ba6950b8da","added_by":"auto","created_at":"2025-06-23 05:00:35","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":44843,"visible":true,"origin":"","legend":"\u003cp\u003eTrends in adolescents reporting depressive symptoms, anxiety symptoms or positive flourishing scores: average gap and inequality gap (2018–2023)\u003c/p\u003e\n\u003cp\u003e2a. The average gap represents the relative distance between the average mental health indicator score and the threshold value.\u003c/p\u003e\n\u003cp\u003e2b. The average inequality gap represents the square of the average gap.\u003c/p\u003e\n\u003cp\u003eProportion adjusted for sex, age, and family-level material deprivation.\u003c/p\u003e\n\u003cp\u003eDepressive symptoms: reverse CESD-R-10 ≤ 20; anxiety symptoms: reverse GAD-7 ≤ 11; or positive flourishing: reverse score ≤ 29.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6933580/v1/499eb90545c4c83247fb2035.png"},{"id":85168858,"identity":"f1e7e89a-d8c6-4db1-8adc-16256c31dd32","added_by":"auto","created_at":"2025-06-23 05:00:35","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":60393,"visible":true,"origin":"","legend":"\u003cp\u003eTrends in depressive symptoms, anxiety symptoms, and positive flourishing scores prevalence among adolescents (2018–2023), stratified by sex\u003c/p\u003e\n\u003cp\u003eProportion adjusted for age, and family-level material deprivation.\u003c/p\u003e\n\u003cp\u003eDepressive symptoms: reverse CESD-R-10 ≤ 20; anxiety symptoms: reverse GAD-7 ≤ 11; or positive flourishing: reverse score ≤ 29.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6933580/v1/1deffa6a9cc7339334a9d63f.png"},{"id":85168859,"identity":"acae2555-25c0-4f2f-9ac5-60832d7d02d8","added_by":"auto","created_at":"2025-06-23 05:00:36","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":52359,"visible":true,"origin":"","legend":"\u003cp\u003eTrends in the average gap from the threshold value across adolescents reporting depressive symptoms, anxiety symptoms or positive flourishing scores (2018–2023), stratified by sex\u003c/p\u003e\n\u003cp\u003eProportion adjusted for sex, age, and family-level material deprivation.\u003c/p\u003e\n\u003cp\u003eDepressive symptoms: reverse CESD-R-10 ≤ 20; anxiety symptoms: reverse GAD-7 ≤ 11; or positive flourishing: reverse score ≤ 29.\u003c/p\u003e\n\u003cp\u003eThe average gap represents the relative distance between the average mental health indicator score and the threshold value.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6933580/v1/edf7409a078f0f5b09b71701.png"},{"id":85170239,"identity":"f7852898-6c04-4d10-9b59-376f3bc94f5e","added_by":"auto","created_at":"2025-06-23 05:32:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":909394,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6933580/v1/9559d63a-cbd0-4891-b795-9232b68ee28f.pdf"},{"id":85168850,"identity":"3a13ca8e-6797-4f9f-ada6-036a3f078fc2","added_by":"auto","created_at":"2025-06-23 05:00:35","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":585848,"visible":true,"origin":"","legend":"","description":"","filename":"AppendixF2.docx","url":"https://assets-eu.researchsquare.com/files/rs-6933580/v1/156e0d247305bc2e35d54cf0.docx"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003eInequality of Adolescents’ Mental Health between 2018 and 2023: Repeated Cross-sectional Evidence from COMPASS\u003c/p\u003e","fulltext":[{"header":"Background","content":"\u003cp\u003eThe COVID-19 pandemic and its associated disruptions, including restrictions and school closures, significantly altered adolescent lifestyles\u0026mdash;reducing social interactions (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e), decreasing physical activity (\u003cspan additionalcitationids=\"CR4 CR5 CR6 CR7 CR8\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e), and increasing screen time (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan additionalcitationids=\"CR7 CR8\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). These lifestyle shifts contributed to both short- and long-term mental health challenges (\u003cspan additionalcitationids=\"CR11 CR12 CR13 CR14 CR15\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e), particularly in a population already facing a decade-long rise in mental health issues (\u003cspan additionalcitationids=\"CR18 CR19 CR20 CR21\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Reviews of adolescent mental health during the pandemic underscore a heterogeneous decline (\u003cspan additionalcitationids=\"CR11 CR12 CR13 CR14 CR15\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e), influenced by local contexts, public health restrictions, and study designs (\u003cspan additionalcitationids=\"CR13\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDespite ample research on adolescent mental health during the pandemic, studies examining the evolution of mental health trajectories beyond 2022 remain limited (\u003cspan additionalcitationids=\"CR24 CR25 CR26 CR27 CR28\" citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e). Recent findings reveal mixed trajectories. In Switzerland, well-being among 14\u0026ndash;25-year-olds declined from 2017 to 2022, with improvements in negative indicators only emerging in 2022\u0026mdash;though the steepest drop in positive indicators preceded the pandemic (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e). In Iceland, adolescents continued to report high depressive symptoms and reduced well-being two years into the pandemic (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). In Finland, the prevalence of depressive and anxiety symptoms remained elevated between 2021 and 2023, with a deterioration in mental well-being scores (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). Girls\u0026mdash;especially in lower secondary education\u0026mdash;showing increased symptoms of anxiety, while boys reported lower social anxiety (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). By 2023, over 70% of girls and 30% of boys in Finland reported at least one mental health issue (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). In the UK, no improvement was observed between spring 2022 and spring 2023 (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e). In the Netherlands, improvements noted in 2022 were reversed in 2023 (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e). These ongoing challenges may stem from the pandemic, pre-existing trends, or greater awareness of mental health (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e), echoing findings that symptoms can persist for years post-trauma (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e) and that loneliness may have long-lasting effects (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). Vulnerable groups\u0026mdash;such as girls (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e), older adolescents (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e), and youth from disadvantaged backgrounds (\u003cspan additionalcitationids=\"CR33\" citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e)\u0026mdash;remain at heightened risk, though little is known about their recovery patterns.\u003c/p\u003e \u003cp\u003eMental health encompasses not only the absence of disorders but also a dynamic state of emotional, psychological, and social well-being that supports coping, relationships, and community participation (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e). Flourishing reflects this optimal state, marked by positive emotions, purpose, personal growth, and strong social relationships (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e). The Diener Flourishing Scale captures these dimensions, offering a broader perspective on personal development (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e). Including flourishing in mental health research shifts the focus beyond pathology to highlight protective factors that foster resilience and thriving (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e). While well-being declined during the pandemic, its post-pandemic trajectory may be distinct from that of negative mental health indicators, possibly due to the time and stability required to rebuild positive functioning (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e).\u003c/p\u003e \u003cp\u003ePrevious studies tend to focus on average symptom scores or prevalence, which, while informative, can mask underlying disparities. For instance, a stable average score may mask increasing disparities if mental health improves for some subgroups while others worsen. Similarly, equal increases in prevalence across subgroups do not necessarily indicate greater inequality. To better capture these dynamics, researchers can use distributional measures, which offer a more nuanced understanding beyond simple averages or proportions (\u003cspan additionalcitationids=\"CR40\" citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e). These types of tools, originating from economics, provide a robust framework to assess not only how many adolescents are struggling, but also the extent of their challenges and how far they are from optimal mental well-being. Despite their significant potential to reveal the concentration and depth of mental health challenges and to determine whether difficulties have become more pronounced or if disparities by sex, age, and socioeconomic status have persisted or widened over time, such methods remain underutilized in public health research.\u003c/p\u003e \u003cp\u003eGiven the mixed\u0026mdash;and in some cases, worsening\u0026mdash;trends reported in recent studies, it remains unclear whether adolescent mental health has stabilized, continued to deteriorate, or begun to improve in the aftermath of the COVID-19 pandemic. To address this uncertainty, our study examines recent trends using both negative indicators (self-reported depressive and anxiety symptoms) and a positive indicator (flourishing). We aim to assess whether adolescent mental health has stabilized or improved after 2022, and whether these trajectories differ by demographic and socioeconomic characteristics. We propose two hypotheses. First, we hypothesize that during the COVID-19 pandemic, the prevalence of depressive and anxiety symptoms increased while flourishing decreased, with all three indicators stabilizing after 2022. At the same time, we hypothesized that the Gini index, the average gap, and the average inequality gap increased during the during the COVID-19 pandemic and stabilizing after 2022. Second, we hypothesize that the disparities between sexes, age groups, and levels of material deprivation accentuated during the pandemic and persisted beyond 2022 into the recovery phase. We expect the recovery in prevalence, average gap, and average inequality gap to be slower for girls, older adolescents, and individuals from materially deprived families compared to their counterparts.\u003c/p\u003e "},{"header":"Methodology","content":"\u003cp\u003eStudy design and participants\u003c/p\u003e \u003cp\u003eWe utilized data from the COMPASS study on adolescent health (Cannabis Use, Obesity, Mental Health, Physical Activity, Alcohol Use, Smoking, and Sedentary Behaviour) (\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e). COMPASS is a study based on school cohorts. Each year, youth in participating high schools are asked to complete a questionnaire about their lifestyle and behaviors. In the province of Quebec, school surveys have been conducted in partnership with school communities and regional public health departments. For this analysis, data were drawn from students attending a cohort of thirty-one high schools in Quebec (Canada) between 2018 and 2023. The schools were from three administrative regions of Quebec: twenty-three from Capitale-Nationale, six from Saguenay-Lac-Saint-Jean and two from Chaudi\u0026egrave;re-Appalaches. Among these, two were urban private schools, and eleven were rural public schools. The remaining eighteen schools were urban public schools. A repeated cross-sectional design was employed to examine changes over this period. This approach enables comparisons across the pre-pandemic (2018 and 2019), peri-pandemic (2021), and post-pandemic (2022 and 2023) periods, providing insights into how trends evolved over time. The severity of public health measures in Quebec during the COVID-19 pandemic fluctuated across different waves. Between March 2020 and March 2022, the government implemented a range of measures, including lockdowns, school closures, curfews, mandatory mask-wearing, and social distancing protocols (\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e) (see Table A1 in the Appendix for more details). Every adolescent attending the participating schools was eligible to participate. An active-information passive-consent parental permission protocol was followed. Parents were informed of the study via email. All participants provided assent.\u003c/p\u003e \u003cp\u003eThe data collection periods included the spring of 2018 (89.6% response rate), 2019 (92.2% response rate), 2021 (72.9% response rate), 2022 (84.6% response rate), and 2023 (85.3% response rate). An annual average of approximately 13,500 adolescents aged between 12 and 17 years old participated in the COMPASS survey. Data from 2020 were excluded from the main analysis because of a low response rate (37.0%) due to the impact of the COVID-19 pandemic on school-based data collection (\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e). In 2018 and 2019, student data were collected via paper-and-pencil surveys that were completed during a classroom period and included entire school samples. Since 2021, surveys have been completed online via Qualtrics XM online survey software (Qualtrics, Provo, UT, USA), require a classroom period, and include entire school samples (\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e). Further information on the transition to online questionnaires and the challenges encountered during data collection in 2020 are presented in Reel, Battista, and Leatherdale (2020).\u003c/p\u003e \u003cp\u003eMeasures\u003c/p\u003e \u003cp\u003eDepressive symptoms. Depressive symptoms were measured via the 10-item Center for Epidemiologic Studies Depression Scale Revised (CESD-R-10) (\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e). The students were asked 10 questions on how often they experienced each symptom within the last 7 days (e.g., \u0026ldquo;I felt that everything I did was an effort\u0026rdquo;). The scores were summed to create a total score ranging from 0 to 30; higher scores indicated greater depressive symptoms. According to past research, a CESD-R-10 score equal to or greater than 10 indicates significant depressive symptoms (\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e). Past studies have validated the CESD-R-10 scale as a reliable measure of depressive symptom severity in adolescents, which has strong internal consistency and test-retest reliability (\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e, \u003cspan additionalcitationids=\"CR48 CR49\" citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e). Its validity has been confirmed in both clinical and nonclinical adolescent populations through its ability to distinguish between individuals with and without depression, as well as its strong correlations with clinical diagnoses and other psychological assessments (\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e, \u003cspan additionalcitationids=\"CR48 CR49\" citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e). Data from the COMPASS have shown that the CESD scale respects strict measurement invariance according to grade, age and sex (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e). Previously, the COMPASS study consistently reported strong internal reliability, with Cronbach's alpha values exceeding 0.70 across multiple years (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAnxiety symptoms. Anxiety symptoms were reported by participants via the 7-item Generalized Anxiety Disorder Scale (GAD-7) (\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e). The students were asked 7 questions on how often they experienced each symptom in the last 2 weeks (e.g., \u0026ldquo;Not being able to stop or control worrying\u0026rdquo;). The scores were summed to create a total score ranging from 0 to 21; higher scores indicated greater anxiety symptoms. According to past research, a GAD-7 score smaller than 10 indicates no to mild anxiety symptoms, whereas a score equal to or greater than 10 indicates moderate to severe anxiety symptoms (\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e). In both clinical and nonclinical populations of adults and adolescents, GAD-7 scores show strong correlations with other measures of anxiety and emotional distress (\u003cspan additionalcitationids=\"CR54\" citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e) and exhibit strict measurement invariance across grades, ages, and sex in previous COMPASS data (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e). Previously, COMPASS has demonstrated strong internal reliability, with Cronbach's alpha values exceeding 0.88 across multiple years (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFlourishing scale. We measured psychological well-being using an 8-item Flourishing Scale, adapted from Diener (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e). Participants answered 8 questions like \"I lead a purposeful and meaningful life\" on a 5-point Likert scale (1\u0026thinsp;=\u0026thinsp;strongly disagree, 5\u0026thinsp;=\u0026thinsp;strongly agree). Total scores range from 8 to 40, with higher scores indicating greater psychological well-being (encompassing positive relationships, competence, meaning, and purpose). These scores are strongly correlated with other measures of psychological and social well-being (\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e). While our 5-point scale differs from Diener's original 7-point Likert scale (scores 8\u0026ndash;56) (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e), this adapted version has demonstrated strong internal reliability and measurement invariance within the COMPASS sample (\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e), with Cronbach's alpha scores consistently at 0.90 across multiple COMPASS years (\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe mean flourishing score in this sample, ranging from 31\u0026ndash;33, appears lower than lower than averages reported using the original scale (e.g., 44.97 or 42.6\u0026ndash;48.1 (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e)). However, a mean score of 32 out of 40 on our adapted scale, representing 80% of the maximum possible score, is comparable to a mean of 45 out of 56 on the original scale. This suggests that participants in this study report similar levels of flourishing to those found in other normative populations.\u003c/p\u003e \u003cp\u003eSince the Flourishing Scale lacks validated cut-off points, we established a threshold. A score of 30, corresponding to the 20th percentile of the distribution, was selected. The 20th percentile was specifically selected to fall between the pre-pandemic percentiles observed for adolescents with depressive or anxiety symptoms (i.e., a CESD-R-10 score of 10 corresponded to the 25th percentile, and a GAD-7 score of 10 corresponded to the 15th percentile). This exploratory cut-off is practical but should be interpreted with caution. It may reflect the absence of symptoms or positive mental health rather than \"optimal\" flourishing. Future research is needed to validate this cut-off.\u003c/p\u003e \u003cp\u003eCovariates. The participants provided their age and sex. Sex was categorized as either boys or girls. The gender question in the COMPASS was updated in 2021 to include nonbinary options. To ensure consistency with the 2018 and 2019 questionnaires, participants identified as neither male nor female were excluded from the analysis. Family-level material deprivation was assessed via a score based on adolescents\u0026rsquo; responses to at least four out of seven questions regarding their living conditions and personal expenses. The questions included 1) the average amount of money they receive weekly for personal spending or savings; 2) skipping breakfast due to a lack of food at home; 3) going to bed hungry because there is not enough money to buy food; 4) perceiving their family as less financially comfortable than the average student in their class; 5) having their own bedroom; 6) the number of people living in their household; and 7) worrying about their family\u0026rsquo;s ability to pay bills and expenses. The composite scores were then divided into two categories: more deprived and less deprived (\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e).\u003c/p\u003e \u003cdiv id=\"Sec2\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eMethods inspired by the Gini coefficient\u003c/p\u003e \u003cp\u003eFirst, we used the Gini coefficient to quantify inequalities in the distribution of mental health outcomes (\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e). The Gini coefficient, a measure commonly used in economics to assess income inequality, has also been applied to quantify the distribution of health (\u003cspan additionalcitationids=\"CR60\" citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e). It ranges from 0 (perfect equality, where all individuals have the same mental health outcome) to 1 (complete inequality, where all mental health issues are concentrated in one individual) (\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e). In our study, the Gini index was used to measure disparities in mental health outcomes (CESD-R-10, GAD-7, and the Flourishing Scale) among adolescents via Stata 17 (\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e) and the \u003cem\u003eineq\u003c/em\u003e command from the Distributive Analysis Stata Package (\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e). A higher Gini mental health index indicates wider gaps in these outcomes between individuals. The interpretation of these indices helps highlight whether mental health outcomes are becoming more or less equitable over time.\u003c/p\u003e \u003cp\u003eFoster-Greer-Thorbecke (FGT) indices\u003c/p\u003e \u003cp\u003eOur study employed statistical methods inspired by poverty analysis techniques adapted for application in health research (\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e). These methods focus on identifying unmet need determined by a threshold value. In this case, the threshold values are the scale cut-offs used to assess depressive symptoms (CESD-R-10 score\u0026thinsp;\u0026ge;\u0026thinsp;10), anxiety symptoms (GAD-7 score\u0026thinsp;\u0026ge;\u0026thinsp;10), or positive flourishing scores (Flourishing Scale score\u0026thinsp;\u0026ge;\u0026thinsp;30). Using an adaptation of the FGT indices (\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e), we estimated the prevalence, average gap, and average inequality gap in these outcomes using ratio-scale variables (see explanation below).\u003c/p\u003e \u003cp\u003eTo apply FGT-inspired indices, ratio-scale variables were ordered in ascending value, starting with the group of interest (i.e., adolescents reporting poorer mental health for negative indicators and those reporting flourishing for the Flourishing Scale) and extending to the rest of the sample. To enable this consistent ordering, we reversed the scoring of the CESD-R-10, GAD-7, and Flourishing scales so that lower values corresponded to greater symptom severity or better outcomes for the flourishing score. This was done by subtracting each participant\u0026rsquo;s raw score from the maximum possible score for each scale (i.e., 30 for CESD-R-10, 21 for GAD-7, and 40 for the Flourishing Scale). For example, a raw CESD-R-10 score of 16 was transformed to an inverted score of 14 (30\u0026ndash;16\u0026thinsp;=\u0026thinsp;14), where lower scores indicated worse mental health.\u003c/p\u003e \u003cp\u003eThis transformation allowed us to apply a consistent \u0026ldquo;shortfall\u0026rdquo; logic across all indicators. The new thresholds defining unmet need became\u0026thinsp;\u0026le;\u0026thinsp;20 for depressive symptoms, \u0026le; 11 for anxiety symptoms, and \u0026le;\u0026thinsp;29 for flourishing, corresponding respectively to the original cut-offs of CESD-R-10\u0026thinsp;\u0026ge;\u0026thinsp;10, GAD-7\u0026thinsp;\u0026ge;\u0026thinsp;10, and Flourishing Scale\u0026thinsp;\u0026ge;\u0026thinsp;30. To help interpret these threshold values, histograms of the CESD-R-10, GAD-7, and Flourishing Scale scores are presented in the Appendix (Figure A2, A3, and A4).\u003c/p\u003e \u003cp\u003eThe prevalence reflects the proportion of adolescents above the thresholds, i.e., reporting depressive symptoms (CESD-R-10 score\u0026thinsp;\u0026ge;\u0026thinsp;10), anxiety symptoms (GAD-7 score\u0026thinsp;\u0026ge;\u0026thinsp;10) or positive flourishing score (Flourishing Scale score\u0026thinsp;\u0026ge;\u0026thinsp;30). It was estimated via adjusted logistic regression with Stata 17\u0026rsquo;s logit command, generating results with 95% confidence intervals (\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe average gap quantified the mean deviation from the thresholds. It is calculated as a relative measure of the average mental health gap between the threshold score and the average CESD-R-10 score (\u0026ge;\u0026thinsp;10), GAD-7 score (\u0026ge;\u0026thinsp;10) or positive flourishing score (\u0026ge;\u0026thinsp;30). As the scores are normalized relative to the threshold, the average gap is always bounded between 0 and 1. A greater gap indicates that adolescents are farther from reaching the threshold to not report depressive symptoms, anxiety symptoms, or positive flourishing score. For example, an average gap of 10% indicates that adolescents reporting depressive symptoms are, on average, within 10 percentage points of the threshold for not reporting these symptoms. This provides a relative measure of the effort required for these average adolescents to no longer report depressive symptoms.\u003c/p\u003e \u003cp\u003eThe average inequality gap reflects the overall magnitude of the disparities. Mathematically, it represents the square of the average gap of everyone below the threshold. As the scores are normalized relative to the threshold, the average inequality gap is always bounded between 0 and 1. The greater the gap is, the further adolescents at the lower end are from the threshold value. For example, a 5% average inequality gap suggests that the adolescents farthest from the threshold value (at the lower end) require 5% more effort than the average adolescent reporting depressive symptoms to stop reporting depressive symptoms. (A visual explanation of the three indices is available in Appendix Figure A1.)\u003c/p\u003e \u003cp\u003eThe average gap and average inequality gap indices were calculated for each participant. To obtain aggregate values, we used the \u003cem\u003eglm\u003c/em\u003e command with a gamma distribution and log link in Stata 17 (\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTo summarize the Foster-Greer-Thorbecke (FGT) framework (\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e) we just explained, it allowed us to assess:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003ePrevalence (Headcount): The proportion of individuals below a defined threshold, comparable to prevalence based on a scale cut-off.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eAverage Gap (Depth): The average \"distance\" participants fall below a threshold (scale cut-off), reflecting the severity of the difficulties within this group.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eAverage Inequality Gap (Severity): The level of inequality among those below a threshold (scale cut-off), indicating how unevenly difficulties are distributed within this group.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eIt's important to note that we adapted these indices to quantify mental health disparities and are not using them to measure socioeconomic poverty.\u003c/p\u003e \u003cp\u003eWe examined differences between sexes in terms of prevalence and average gap via year \u0026times; sex interaction terms. Differences between age and between family-level material deprivation were examined (see Tables A8 and A9 and Figures A5, A6, A7, and A8 in the appendix).\u003c/p\u003e \u003cp\u003eAll analyses considered the clustering of individuals within schools\u0026rsquo; robust covariance. They were conducted via Stata 17 (\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e), and adjusted results by year were obtained via the \u003cem\u003emargins\u003c/em\u003e command (\u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e). We conducted a complete case analysis (Further information on missing data can be found in tables A5 and A6 in the appendix.)\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003ePopulation characteristics\u003c/p\u003e\n\u003cp\u003eAs shown in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e, the percentage of boys ranged from 44.5\u0026ndash;47.7%, with slight fluctuations over time. The average age remained consistent at approximately 14.5 years. Over the same period, there was a notable increase in the proportion of adolescents classified in the most deprived category of family-level material deprivation, increasing from 23.7% in 2018 to 36.1% in 2023. The average depressive symptoms increased from 7.4 to 8.9, the average anxiety symptoms increased from 5.0 to 6.4, and the average flourishing score decreased from 33.2 to 31.4 during this time frame.\u0026nbsp;\u003c/p\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eCharacteristics of Quebec adolescents who participated in the COMPASS study (2018\u0026ndash;2023)\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003ePre-pandemic\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePeri-pandemic\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003ePost-pandemic\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e2018\u003c/p\u003e\n \u003cp\u003e(N\u0026thinsp;=\u0026thinsp;14,320)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e2019\u003c/p\u003e\n \u003cp\u003e(N\u0026thinsp;=\u0026thinsp;14,796)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e2021\u003c/p\u003e\n \u003cp\u003e(N\u0026thinsp;=\u0026thinsp;11,937)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e2022\u003c/p\u003e\n \u003cp\u003e(N\u0026thinsp;=\u0026thinsp;13,926)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e2023\u003c/p\u003e\n \u003cp\u003e(N\u0026thinsp;=\u0026thinsp;17,042)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eSex\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBoys\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6,829 (47.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e7,035 (47.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5,315 (44.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6,387 (45.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8,102 (47.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMissing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e67 (0.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e118 (0.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e183 (1.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e250 (1.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e198 (1.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMean (SD)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.7 (1.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e14.6 (1.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.5 (1.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.4 (1.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.5 (1.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMissing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e42 (0.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e85 (0.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e150 (1.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e156 (1.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e123 (0.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e\u003cstrong\u003eFamily-level material deprivation\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMore deprived\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3,396 (23.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3,396 (23.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3,923 (32.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5,141 (36.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6,157 (36.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMissing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e39 (0.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e218 (1.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e196 (1.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e153 (0.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eCESD-R-10\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026ge;\u0026thinsp;10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3,365 (23.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4,058 (27.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4,238 (35.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5,087 (36.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5,769 (33.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMean (SD)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.4 (5.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8.1 (5.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.4 (6.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.5 (6.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.9 (6.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMissing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,890 (13.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2,061 (13.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,676 (14.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,735 (12.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,577 (9.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eGAD-7\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026ge;\u0026thinsp;10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2,171 (15.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2,372 (16.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2,709 (22.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3,600 (25.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4,034 (23.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMean (SD)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.0 (4.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.2 (4.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.4 (5.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.9 (5.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.4 (5.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMissing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,231 (8.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1,385 (9.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,346 (11.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,327 (9.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,241 (7.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eFlourishing scale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026ge;\u0026thinsp;30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10,677 (78.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10,852 (78.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7,712 (71.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8,675 (67.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4,902 (66.0%)*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMean (SD)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e33.2 (5.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e33.1 (5.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e32.3 (5.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e31.7 (6.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e31.4 (6.5)*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMissing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e721 (5.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e874 (5.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,117 (9.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,131 (8.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e818 (9.9%)*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e* The questionnaire on flourishing was completed by a total of 8,241 adolescents in 2023.\u003c/p\u003e\n\u003cp\u003eTrends in mental health\u003c/p\u003e\n\u003cp\u003eWe observed a decline in adolescents\u0026rsquo; mental health during the COVID-19 pandemic (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e, part a). Between the peri-pandemic (2021) and post-pandemic (2022) periods, the prevalence of adolescents reporting depressive symptoms stabilized at 41%, whereas anxiety symptoms (28%) and positive flourishing (69%) continued to deteriorate. In the post-pandemic period (2023), we observed lower levels of depressive and anxiety symptoms, with 37% and 25%, respectively. The prevalence of adolescents with positive flourishing decreased to 67%.\u003c/p\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e (part b) illustrates the growth in mental health inequalities from pre- (2019) to peri-pandemic (2021) for the three mental health indicators using methods inspired by the Gini coefficient. This growth persists post-pandemic, reaching 22% for anxiety symptoms in 2022 and 11% for flourishing scores in 2023. This finding indicates that the disparities between individuals continue to widen post-pandemic over the GAD-7 and the Flourishing Scale. However, by 2023, there was a slight decline in inequality for depressive and anxiety symptoms, reaching 16% and 21%, respectively. This finding indicates that the Gini mental health index might slowly return to pre-pandemic levels. This suggests that the distributions of the CESD-R-10 and GAD-7 scores became more uniform, with fewer extreme differences between adolescents.\u003c/p\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e focuses on adolescents reporting depressive symptoms, anxiety symptoms, and positive flourishing scores. This finding shows that adolescents\u0026rsquo; mental health has continued to degrade over the years. In 2023, adolescents reported an average gap from the threshold of 31% for depressive symptoms, 44% for anxiety symptoms, and 22% for the positive flourishing score (part a). The situation has improved compared with that in 2021 and 2022 for depressive and anxiety symptoms but remains worse than that in the pre-pandemic period. Moreover, the average adolescent with a positive flourishing score gradually moved closer to the lower flourishing threshold over time. Figure \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e, part b shows only a slight increase in the average inequality gap compared with the pre-pandemic values for depressive symptoms (14%) and the positive flourishing score (10%) in 2023. However, anxiety symptoms rose from 24% in 2018 to 28% in 2023. This finding indicates that adolescents with higher depressive symptoms or positive flourishing scores maintained approximately the same levels over time, whereas those with higher anxiety symptoms became increasingly anxious.\u003c/p\u003e\n\u003cp\u003eStratification by sex, age, and family-level material deprivation\u003c/p\u003e\n\u003cp\u003eA greater proportion of girls reported depressive symptoms and anxiety symptoms, and fewer reported a positive flourishing score than boys did (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). We focus here on sex-based differences, as they revealed the largest and most consistent inequalities across all mental health indicators. This sex difference increased over time. Between the pre-pandemic period (2019) and the peri-pandemic period (2021), the prevalence of girls reporting depressive symptoms increased by 11.2 percentage points, reaching 53% in 2021 (Table A7, Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). However, boys experienced an increase of 4.7 percentage points, reaching 26% in 2021 (Table A7, Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). This highlights a growing disparity, as the prevalence of depressive symptoms increased by 6.6 percentage points more for girls than for boys. By 2023, boys had returned to pre-pandemic levels (21%), whereas girls remained 8.5 percentage points above their pre-pandemic prevalence, reflecting a greater overall increase of 8.7 percentage points for girls. A similar pattern was observed for anxiety symptoms. However, unlike depression and anxiety, the proportion of both boys and girls reporting positive flourishing continued to decline over time.\u003c/p\u003e\n\u003cp\u003eThe average gap from the threshold of adolescents reporting depressive symptoms, anxiety symptoms or positive flourishing scores presented a comparable trend (Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e). The sex difference increased over time. Boys reported an average depressive symptom gap of 26% after the pandemic (2023), which was nearly the same as that reported before the pandemic (2019). However, girls reported an average depressive symptom gap of 33% after the pandemic (2023), an increase of 2.6 percentage points from pre-pandemic levels (2019). No significant difference between sexes was observed for the positive flourishing score.\u003c/p\u003e\n\u003cp\u003eA greater proportion of older adolescents reported depressive symptoms or anxiety symptoms, and a lower proportion of older adolescents reported positive flourishing scores (Figure A5). The prevalence trends were similar for the two age groups (Table A8). The average gap in anxiety symptoms suggests that symptoms became more pronounced among adolescents aged 13 years and younger from pre-pandemic (2019) to post-pandemic (2023), reaching 44%, a level similar to that of adolescents aged 14 years and older (Figure A6). It represented an increase of more than 4.8 percentage points compared with adolescents aged 14 and older (Table A6). (See appendix for figures A5 and A6 and for Table A8.)\u003c/p\u003e\n\u003cp\u003eStratification by family-level material deprivation indicated that a greater proportion of more deprived adolescents reported depressive symptoms or anxiety symptoms, while fewer reported positive flourishing scores than did their less deprived peers (Figure A7). This difference increased from pre- to post-pandemic values of approximately three percentage points (Table A9). The average gap increased by 4.6 percentage points for anxiety symptoms but decreased by 3.3 percentage points for the positive flourishing score between adolescents from both more and less deprived families over the period (Figure A8, Table A7). This suggests that adolescents from less deprived families are experiencing symptoms more similar to those of adolescents from more deprived families. (See the Appendix for figures A7 and A8 and table A9.) These analyses were conducted across age groups and levels of family material deprivation; while the results are discussed in the main text, the corresponding figures and tables are presented in the Supplement.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study provides a portrait of adolescents\u0026rsquo; mental health trends from 2018 to 2023, using complementary indicators such as the Gini index and three indices derived from the FGT framework: prevalence, average gap from threshold, and average inequality gap. Together, these measures reveal not only how many adolescents are affected, but also how severely and how unequally mental health burdens are distributed across the population. Whereas the FGT inequality gap focuses on disparities among those below a threshold, the Gini index captures inequality across the full distribution of mental health scores, offering a complementary view of concentration.\u003c/p\u003e \u003cp\u003eAcross all indicators, we observed a marked deterioration in adolescents\u0026rsquo; mental health during the COVID-19 pandemic. This decline persisted in 2022, with elevated prevalence rates, more severe symptoms (as reflected by a larger average gap), and increased inequalities (as reflected by a larger average inequality gap) among adolescents experiencing depressive symptoms, anxiety, or positive flourishing. These findings are consistent with prior literature highlighting a pandemic-related surge in psychological distress among youth (\u003cspan additionalcitationids=\"CR11 CR12 CR13 CR14 CR15\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eImportantly, our data reveal diverging post-pandemic trajectories across mental health dimensions. While all indices of depressive and anxiety symptoms\u0026mdash;prevalence, average gap, and inequality\u0026mdash;improved in 2023, suggesting partial recovery and resilience, the flourishing score declined further across these same dimensions. This persistent downward trend in positive mental health, even after the easing of public health restrictions, is particularly concerning. It suggests that while symptoms may have receded, adolescents\u0026rsquo; deeper sense of well-being, purpose, and connection remains compromised. This echoes prior work showing that flourishing encompasses broader psychological and social dimensions\u0026mdash;such as optimism, meaning in life, and social connectedness\u0026mdash;that may be slower to recover (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe combined use of prevalence, average gap, and inequality gap indicators highlights that improvements in average mental health do not necessarily translate into more equitable outcomes. For instance, although the prevalence of depressive symptoms declined between 2022 and 2023, the average gap barely decreased. This suggests that some subgroups of adolescents continue to experience disproportionately high levels of distress\u0026mdash;an issue that would remain hidden if only prevalence were considered. The Gini index and FGT-based indices are particularly valuable in this regard, as they capture the extent to which mental health or low flourishing is concentrated among a minority of adolescents. This provides a more equity-sensitive lens that is critical for monitoring population mental health.\u003c/p\u003e \u003cp\u003eBeyond population-wide trends, stratified analyses reveal persistent and widening inequalities. Our stratified analyses reinforce this point. Girls, older adolescents, and those from more materially deprived families consistently reported worse mental health outcomes across all three mental health indicators. Notably, sex-based disparities in depressive and anxiety symptoms have widened over time: in 2023, boys largely returned to pre-pandemic levels, while girls remained significantly above their 2019 baselines. This is consistent with research showing that girls and older adolescents are more vulnerable to mental health challenges during crises like the COVID-19 pandemic (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e), possibly due to developmental or hormonal factors (\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e, \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e). Similarly, adolescents from less materially deprived families experienced greater post-pandemic declines in flourishing and anxiety symptoms than their more deprived peers, narrowing the socioeconomic gap but due to worsening outcomes among advantaged groups rather than improvement among vulnerable ones. This pattern highlights the importance of interpreting convergence in inequalities carefully, as it may mask population-wide declines rather than signal progress toward equity.\u003c/p\u003e \u003cp\u003eThese findings challenge a narrow interpretation of adolescent recovery. The apparent rebound in symptom prevalence masks persistent disparities and continued erosion of well-being. A holistic understanding of youth mental health post-COVID requires attention not only to the presence or absence of symptoms, but also to broader social and psychological indicators, and how these are distributed across populations.\u003c/p\u003e \u003cp\u003eFrom a public health perspective, this multidimensional decline observed across mental health indicators calls for sustained investment in adolescent well-being\u0026mdash;beyond short-term crisis response. Relying solely on prevalence metrics is insufficient. Incorporating measures of severity (average gap) and inequality (inequality gap) provides a more equity-sensitive approach to monitoring and addressing mental health needs. Moreover, flourishing\u0026mdash;representing broader dimensions of meaning, optimism, and connection\u0026mdash;should be systematically tracked alongside symptoms of distress. Effective responses must combine universal and targeted strategies. Schools, families, and communities should be supported to create protective environments through upstream interventions like social-emotional learning and school-wide mental health promotion (\u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e67\u003c/span\u003e, \u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e68\u003c/span\u003e). At the same time, resources must be directed toward the most affected groups, particularly girls, older adolescents, and those experiencing material deprivation (\u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e69\u003c/span\u003e). A holistic, equity-oriented approach is essential to rebuild a foundation for long-term youth well-being (\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e) (\u003cspan citationid=\"CR70\" class=\"CitationRef\"\u003e70\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eLimitations\u003c/p\u003e \u003cp\u003eA few limitations should be mentioned. First, the shift from paper-based questionnaires to online questionnaires may have influenced respondents\u0026rsquo; answers. However, the reliability of these scales has remained consistently high. Moreover, a study specifically examining this transition reported measurement invariance in the CESD-R-10 among adolescents (\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e). Second, Quebec may have implemented different infection control measures and experienced different stages of the COVID-19 pandemic at various time points than other provinces or countries did. Therefore, our findings may not be broadly applicable to regions beyond Quebec. Moreover, due to the cross-sectional nature of our data and the dynamic nature of the pandemic, we cannot establish causal relationships regarding the impact of the health crisis on adolescents. Numerous cumulative events occurred during this period, making pinpointing specific causes and effects challenging. Therefore, our focus was primarily on tracking the evolving situation after the health crisis and highlighting the changes and challenges faced by adolescents.\u003c/p\u003e \u003cp\u003eWe excluded data from the spring of 2020 from the main results because of the low participation rates during school closures (before online classes were implemented). For additional information, Table A7 and Figure A9 in the Appendix presents results that include the 2020 data. These supplementary findings should be interpreted with caution, as there may have been a selection bias whereby students who participated may have adapted better to the early pandemic context than those who did not participate in the study. This highlights a common challenge in cross-sectional and longitudinal mental health studies conducted during periods of large-scale disruption. Low response rates and rapidly changing conditions may compromise representativeness and limit comparability across time points. These observations underscore the importance of using strategies designs to promote representativeness across time and to adopt longitudinal designs to capture dynamic changes in adolescent mental health during crises.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe findings of this school-based repeated cross-sectional study reveal a divergent evolution of positive and negative constructs of mental health in Quebec, Canada, following the COVID-19 pandemic. While negative mental health indicators showed signs of improvement, positive mental health (flourishing) continued to deteriorate. This highlights that simply focusing on symptom reduction is insufficient; a holistic view is important. Our analyses revealed that girls, older adolescents, and those from families experiencing higher levels of material deprivation remain particularly vulnerable to poorer mental health outcomes, with gender disparities widening over time across all three indicators examined. These findings underscore the need for comprehensive mental health assessments that not only reveal how many adolescents are affected, but also how severely and how unequally mental health burdens are distributed across the population. This broader perspective is essential for developing mental health support that not only reduces symptoms but also actively fosters holistic well-being. Strengthening the role of families, schools, and health systems through integrated and inclusive approaches could be pivotal in helping adolescents navigate future challenges and achieve long-term flourishing.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eEthics approval and consent to participate\u003c/h2\u003e\n\u003cp\u003eThe COMPASS study received ethics approval from the University of Waterloo Office of Research Ethics (ORE#30118) and CIUSSS de la Capitale-Nationale\u0026ndash;Universit\u0026eacute; Laval (#MP-13-2017-1264), and all participating school boards. All procedures were conducted in accordance with the ethical standards of the Helsinki Declaration. Informed consent was obtained from participants and from parents/guardians for all children under 16 years of age. Using active-information, passive-consent protocols, parents/guardians of all eligible students were sent study permission information via email and/or automated school phone system a minimum of two weeks prior to the survey start date, with the option to actively withdraw permission for their child(ren) to participate. Students whose parents did not withdraw consent were invited to participate and could decline participation at any time prior to submitting survey responses.\u003c/p\u003e\n\u003ch2\u003eConsent for publication\u003c/h2\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003ch2\u003eAvailability of data and materials\u003c/h2\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request submitted via the following online application form (https://uwaterloo.ca/compass-system/information-researchers).\u003c/p\u003e\n\u003ch2\u003eCompeting interests\u003c/h2\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThe COMPASS study has been supported by a bridge grant from the CIHR Institute of Nutrition, Metabolism and Diabetes (INMD) through the \u0026ldquo;Obesity \u0026ndash; Interventions to Prevent or Treat\u0026rdquo; priority funding award (OOP-110788; awarded to SL), an operating grant from the CIHR Institute of Population and Public Health (CIHR) (MOP-114875; awarded to SL), a CIHR project grant (PJT-148562; awarded to SL), a CIHR bridge grant (PJT-149092; awarded to Karen A. Patte/SL), a CIHR project grant (PJT-159693; awarded to KAP), a research funding arrangement with Health Canada (#1617\u0026ndash;HQ-000012; contract awarded to SL), a CIHR-Canadian Centre on Substance Use and Addiction (CCSA) team grant (OF7B1-PCPEGT410-10-9633; awarded to SL), and a project grant from the CIHR Institute of Population and Public Health (IPPH) (PJT-180262; awarded to SL and Karen A. Patte). A SickKids Foundation New Investigator Grant, in partnership with the CIHR Institute of Human Development, Child and Youth Health (IHDCYH) (Grant No. NI21-1193; awarded to Karen A. Patte), funds a mixed methods study examining the impact of the COVID-19 pandemic on youth mental health, leveraging COMPASS study data. The COMPASS Quebec project additionally benefits from funding from the Minist\u0026egrave;re de la Sant\u0026eacute; et des Services sociaux of the province of Qu\u0026eacute;bec, the Direction r\u0026eacute;gionale de sant\u0026eacute; publique du CIUSSS de la Capitale-Nationale and the Fonds de recherche du Qu\u0026eacute;bec \u0026ndash; Society and Culture (FRQSC) (Grant No. 2024-0UER-339082).\u0026nbsp;The study is also supported by a CIHR Operating Grant (#179224). AMTT is supported by the research scholar program from the Fonds de Recherche du Qu\u0026eacute;bec\u0026ndash;Sant\u0026eacute;.\u003c/p\u003e\n\u003ch2\u003eAuthors\u0026apos; contributions\u003c/h2\u003e\n\u003cp\u003eThe manuscript was conceptualized by KP, SH, and AMTT. Formal analysis and validation were conducted by KP, SH, and AMTT. KP wrote the first draft of the manuscript and created the tables. The draft was reviewed and edited by AMTT, REB, JJCG, RJG, CBD, SH, and STL. The funding acquisition, project administration and investigation were conducted by SH, REB, STL, AMTT, and CBD. All the authors have had full access to all the data in the study and have final responsibility for the decision to submit for publication.\u003c/p\u003e\n\u003ch2\u003eAcknowledgments\u003c/h2\u003e\n\u003cp\u003eThe authors wish to thank the Quebec public health authorities, participating schools, school boards and students as well as the COMPASS team for their significant contributions.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eOrben A, Tomova L, Blakemore SJ (2020) The effects of social deprivation on adolescent development and mental health. 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Int J Environ Res Public Health. ;18(7)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBattista K, Diao L, Patte KA, Dubin JA, Leatherdale ST (2023) Examining the use of decision trees in population health surveillance: an application to youth mental health survey data in the COMPASS study. Health Promotion Chronic Disease Prev Canada: Res Policy Pract 43(2):73\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"University of Waterloo","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":"Mental health, Depression, Anxiety, Flourishing, Adolescents, Inequalities, Vulnerabilities","lastPublishedDoi":"10.21203/rs.3.rs-6933580/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6933580/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eThe COVID-19 pandemic has disrupted adolescents' lifestyles, negatively impacting their mental health and well-being. To date, few studies have examined the medium- to long-term consequences for adolescents. This study examines the evolution of adolescents\u0026rsquo; mental health using data collected between 2018 and 2023 from a population of adolescents living in Quebec, Canada, with a focus on depressive symptoms, anxiety symptoms, and flourishing scores. It also explores whether specific demographic and socioeconomic groups are disproportionately affected.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe used data collected as part of the COMPASS study from students attending a cohort of 31 high schools in Quebec (Canada). We conducted a repeated cross-sectional analysis from 2018\u0026ndash;2023 involving approximately 13,500 adolescents aged 12\u0026ndash;17 years each year. The mental health indicators included the Center for Epidemiologic Studies Depression Scale Revised (CESD-R-10), the Generalized Anxiety Disorder scale (GAD-7), and the Diener Flourishing Scale. Statistical analyses employed techniques adapted from the Foster-Greer-Thorbecke indices, establishing a minimum threshold for optimal mental health. We examined various metrics, including the prevalence of mental health issues; the average gap and inequality gap from the threshold of adolescents reporting depressive symptoms, anxiety symptoms or positive flourishing score; and a measure of mental health inequality inspired by the Gini coefficient.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe prevalence of depressive symptoms and anxiety symptoms increased during the pandemic, peaking in 2021 and 2022, respectively, before returning close to pre-pandemic levels in 2023. However, flourishing scores continued to decline throughout the study period. Anxiety symptoms show greater inequalities than the other two indicators. Girls, older adolescents, and those from more deprived backgrounds presented poorer mental health, with significant disparities persisting post-pandemic. Gender disparities in mental health have widened both during and after the pandemic.\u003c/p\u003e\u003ch2\u003eDiscussion\u003c/h2\u003e \u003cp\u003eThis study reveals that indicators representing positive and negative constructs of mental health evolve differently over time. While depression and anxiety symptoms gradually returned to prepandemic levels, fewer adolescents reported positive flourishing scores over time, emphasizing the urgency of implementing innovative programs that promote holistic well-being, including having positive relationships, feelings of competence, and meaning and purpose in life.\u003c/p\u003e","manuscriptTitle":"Inequality of Adolescents’ Mental Health between 2018 and 2023: Repeated Cross-sectional Evidence from COMPASS","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-23 05:00:30","doi":"10.21203/rs.3.rs-6933580/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":"4a89e4aa-2d7c-4e39-b1bd-f6b36310afa9","owner":[],"postedDate":"June 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":50317548,"name":"Psychology"},{"id":50317549,"name":"Pediatrics"},{"id":50317550,"name":"Epidemiology"}],"tags":[],"updatedAt":"2025-06-23T05:00:31+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-23 05:00:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6933580","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6933580","identity":"rs-6933580","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}