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Selection of appropriate study design and analytical methods is critical for producing robust research, as the design and analytical approach used can ultimately shape results and their interpretation. The objective of this research was to examine how findings from a large repeat cross-sectional data system compare to those from a sample of longitudinal data nested within the same data system, using milk and milk alternative consumption as a case study. Overall, the repeat cross-sectional and longitudinal findings were consistent, and this article highlights the strengths and limitations of both methodologies under examination. Application to social research and public health and policy are discussed.

Background: The school environment has the potential to influence student body mass index (BMI) through programs and policies. Our objective was to examine the effect of modifying obesity-related school policies and programs on youths' BMI trajectories. Methods: Obesity-related school policies and programs related to physical activity and healthy eating were collected from 41 schools across Ontario at baseline (2012-2013) and year 2 (2013-2014) of the COMPASS study. Self-reported height and weight were collected from the 4951 grades 9 and 10 students who attended those schools for 3 years. Linear mixed effects regression models examined the effect of modifying obesity-related school policies and programs on youths' BMI trajectories. Results: Between Y[subscript 1] and Y[subscript 2], 26 of the 41 schools implemented distinct new obesity-related programs or policies related to physical activity or healthy eating. Five of the interventions were associated with BMI trajectories of students attending those schools compared to students attending a pooled sample of control schools, predicting a higher BMI trajectory. Conclusions: Isolated programs and policies may not successfully improve youths' BMI trajectories. Further research is required to test the implementation of policies and programs that follow a comprehensive school health (CSH) approach, targeting BMI and associated behaviors.

Data from the Canadian Youth Smoking Survey (n = 27,030 in 2006; n = 16,705 in 2004; n = 11,757 in 2002) were used to examine changes in the prevalence and comorbid use of alcohol, tobacco, and marijuana over time and examine if demographic factors and binge drinking are associated with comorbid substance use among youth. Alcohol was the most prevalent substance used, and it was rare to find youth who had used tobacco or marijuana without also having tried alcohol. Youth who reported binge drinking were substantially more likely to also have tried tobacco and/or marijuana. These data suggest that multi-substance prevention programs are required for youth populations.

Youth smoking and physical inactivity are significant public health issues, with implications for both health and education stakeholders, as school-based policies and programs have the potential to reach a broad population of youth to address these issues. Knowledge exchange tools designed around comprehensive school-level data collection systems allow for dissemination of evidence into such policies and programs. The purpose of this manuscript is to describe the process of developing knowledge exchange feedback reports for school-based health policies and programs, using the School Health Action, Planning and Evaluation System (SHAPES) data collection system. SHAPES-Ontario is a project that utilized the SHAPES research platform to collect student-level behavioural data and school-level policy and programs data on tobacco and physical activity in 81 secondary schools across Ontario, Canada. Methods used to develop the feedback reports involved categorizing and scoring survey response options based on extensive research evidence and expert feedback. Feedback report scores were aggregated into overall grades and presented in a short and long version of a feedback report for school administrators. These reports present prime examples of how to use the principles of knowledge exchange in developing a tool to bridge the gap between research and practice. (Contains 3 tables and 2 figures.)

We examined bullying victimization spanning from before the pandemic to the two school years post COVID-19 onset in adolescents. We used survey data from Canadian secondary school students collected during the 2019–20, 2020–21, and 2021–22 academic years. Generalized Estimating Equations models were used to estimate the population average odds of past 30-day bullying victimization by other students, using both longitudinal (N = 3716) and repeat cross-sectional (N = 23,862; 19,413; 21,897) data. The odds of bullying victimization were lower in 2020–21 and higher in 2021–22 relative to 2019–20. Elevated odds of bullying victimization were found among gender diverse, higher weight, and relatively less affluent students. While remote schooling during the pandemic may have provided a reprieve for some students, bullying appears to have rebounded with the lifting of COVID-19 restrictions to exceed pre-pandemic levels. More effective strategies are essential to prevent bullying and improve school contexts for equity denied populations. [ABSTRACT FROM AUTHOR]

Background: Neighborhoods are one setting to promote children's physical activity. This study examined associations between neighborhood features and children's physical activity and whether season or socioeconomic status modified these associations. Methods: Parents (n = 641) of children aged 6–10 years completed the Neighborhood Environment Walkability Scale—Abbreviated. Walkability was objectively measured at 400, 800, and 1200 m around the centroid of participants' postal codes. Children's physical activity was measured via StepsCount pedometers and parental report. Regression analyses were performed with interaction terms for season and socioeconomic status. Multiple imputation was used primarily to triangulate the results for children with missing steps data (n = 192). Results: Higher perceived residential density and traffic hazards were significantly associated with lower squareroot transformed parental-reported physical activity and steps per day, respectively. Higher perceived aesthetics was associated with higher squareroot transformed parental-reported physical activity. Socioeconomic status modified 2 associations though they were not significant upon stratification. During winter months, better perceived infrastructure and safety for walking was associated with higher squareroot transformed parental-reported physical activity. No other significant associations emerged. Conclusion: Residential density, traffic hazards, and aesthetics are important for children's physical activity. Few associations were modified by socioeconomic status or season. The need for objective and subjective measures of the neighborhood environment and children's physical activity is apparent. [ABSTRACT FROM AUTHOR]

This study explores the bidirectional association between internalizing symptoms and alcohol use over three years of the COVID-19 pandemic to examine whether alcohol consumption is associated with higher internalizing symptoms in the next year and vice versa. We used linked data from a sample of 2,136 secondary school students who participated in three consecutive waves (2019–2020 [T1], 2020–2021 [T2], and 2021–2022 [T3]) of the Cannabis use, Obesity, Mental health, Physical activity, Alcohol use, Smoking, and Sedentary behaviour study during the pandemic. A random-intercept cross-lagged panel model was used to characterize reciprocal linear relations between internalizing symptoms and alcohol use. The findings suggest that students who reported higher levels of alcohol use at T1 experienced increased levels of depression and anxiety in the subsequent year (T2). However, this association was not observed from T2 to T3. Throughout the three-year period, depression and anxiety were not associated with later alcohol use. In males, alcohol use at T1 was a predictor of higher internalizing symptoms at T2 but not from T2 to T3. These results suggest time-sensitive impacts and notable gender differences in the relationship between internalizing symptoms and alcohol use over the pandemic. Given the complexity of impacts, ongoing evaluation of the impact of the pandemic on youth health behaviours is necessary to elucidate these unfolding relationships, especially as the pandemic continues to affect various psychosocial risk factors. [ABSTRACT FROM AUTHOR]

BACKGROUND: Income inequality is theorized to impact health. However, evidence among adolescents is limited. This study examined the association between income inequality and health‐related school absenteeism (HRSA) in adolescents. METHODS: Participants were adolescents (n = 74,501) attending secondary schools (n = 136) that participated in the 2018‐2019 wave of the COMPASS study. Chronic (missing ≥3 days of school in the previous 4 weeks) and problematic (missing ≥11 days of school in the previous 4 weeks) HRSA was self‐reported. Income inequality was assessed via the Gini coefficient at the census division (CD) level. Multilevel modeling was used. RESULTS: Greater income inequality was associated with a higher likelihood of chronic and problematic HRSA (chronic: OR = 1.17, 95% CI: 1.06, 1.30; problematic: OR = 1.29, 95% CI 1.11 to 1.50). Increased predicted probabilities for Problematic HRSA were observed at greater degrees of income inequality among students who identified as either white, black, Latinx, or mixed, while protective associations were observed among students who identified as Asian or other. No associations were modified by gender. CONCLUSION: Income inequality demonstrated unfavorable associations with HRSA, which was modified by racial identity. [ABSTRACT FROM AUTHOR]

Introduction: In population health surveillance research, survey data are commonly analyzed using regression methods; however, these methods have limited ability to examine complex relationships. In contrast, decision tree models are ideally suited for segmenting populations and examining complex interactions among factors, and their use within health research is growing. This article provides a methodological overview of decision trees and their application to youth mental health survey data. Methods: The performance of two popular decision tree techniques, the classification and regression tree (CART) and conditional inference tree (CTREE) techniques, is compared to traditional linear and logistic regression models through an application to youth mental health outcomes in the COMPASS study. Data were collected from 74 501 students across 136 schools in Canada. Anxiety, depression and psychosocial well-being outcomes were measured along with 23 sociodemographic and health behaviour predictors. Model performance was assessed using measures of prediction accuracy, parsimony and relative variable importance. Results: Decision tree and regression models consistently identified the same sets of most important predictors for each outcome, indicating a general level of agreement between methods. Tree models had lower prediction accuracy but were more parsimonious and placed greater relative importance on key differentiating factors. Conclusion: Decision trees provide a means of identifying high-risk subgroups to whom prevention and intervention efforts can be targeted, making them a useful tool to address research questions that cannot be answered by traditional regression methods. [ABSTRACT FROM AUTHOR]

To date, there are few longitudinal studies on the COVID-19 pandemic's ongoing impact on youth drinking. This study examines the changes in drinking during two phases of the pandemic in a sample of Canadian youth. We used four-year longitudinal data from the COMPASS study, including 14,085 secondary school students from Quebec and Ontario, Canada who provided linked data for any two consecutive years between 2017/18 and 2018/19 (pre-pandemic) waves, and 2019/20 and 2020/21 (during the initial and ongoing pandemic). A difference-in-difference (D-I-D) model was used to compare changes in the frequency of drinking and binge drinking between pre-COVID-19 to initial- and ongoing-pandemic period, while adjusted for age-related effects. The expected escalation in the frequency of drinking and binge drinking from the pre-pandemic wave (2018/19) to the initial pandemic (2019/20) was less than the changes seen across the 2017/18 to 2018/19 waves among sex and age groups. However, the second year of COVID was associated with an increase in the frequencies of both drinking and binge drinking. Male and younger students (aged 12–14) differentially increased their consumption. After a reduction in the initial pandemic period, the frequency of drinking and binge drinking rebounded in the second year, indicating that the pandemic's effects are not singular and have changed over time. Further examination is needed to understand the ongoing effects of the pandemic by continuing to monitor drinking in youth toward informing public health measures and harm reduction strategies. [ABSTRACT FROM AUTHOR]

Introduction: Canadian youth are insufficiently active, and schools may play a role in promoting student physical activity (PA). Based on the Comprehensive School Health (CSH) framework, this study examined whether school characteristics are associated with secondary school students meeting national PA recommendations over time. Methods: We used COMPASS survey data from 78 schools in Ontario and Alberta and 9870 Grade 9 and 10 students attending those schools. Students who provided two years of linked PA data (2013/14 and 2015/16) and gender were included. Multilevel analysis was conducted by gender, evaluating the relationship of school-level characteristics (guided by CSH) with students achieving all three PA recommendations after two years (≥ 60 min/day of moderate-to-vigorous PA, vigorous PA ≥ 3 days/week, strengthening activities ≥ 3 days/week). Results: More than half (56.9%) of students achieving the PA recommendations at baseline were no longer achieving them after two years, and just a quarter (25.6%) of students not achieving the recommendations at baseline achieved them after two years. School-level factors were significantly associated with students achieving the recommendations, but these factors differed by student strata (i.e. by gender and baseline PA status). Generally, student access to equipment, public health partnerships and staff time for health were associated with increased odds of achieving the PA recommendations for certain students. Conclusion: Modifications to school characteristics within CSH may play a role in supporting students in achieving or continuing to achieve the PA recommendations after two years. Further research is needed to better understand the underlying dynamics of the observed relationships. [ABSTRACT FROM AUTHOR]

BACKGROUND: The comprehensive school health (CSH) framework has four components: social and physical environment; partnerships and services; teaching and learning; and policy. This study examines associations between CSH and student physical activity (PA). METHODS: Using 2015/2016 COMPASS study survey data of 37,397 students (grades 9‐12) from 80 secondary schools in Ontario and Alberta, Canada, associations between school‐level factors within CSH and student PA outcomes (weekly moderate‐to‐vigorous PA [MVPA] minutes and achieving the national PA recommendations of ≥60 min of MVPA daily, vigorous PA ≥3 days/week, strengthening activities ≥3 days/week) were analyzed using multilevel regression models stratified by gender and grade. RESULTS: Factors within all four CSH components were associated with student PA. Four student subgroups were more likely to achieve the recommendations if their school had youth organization partnerships (Range of AORs:1.15‐1.33, p <.05) and female students were less likely if their school had low prioritization of PA (AOR = 0.77, 95% CI: [0.65‐0.92]). Grade 9 students had higher MVPA when provided non‐competitive PA opportunities (β = 100.4, 95%CI: [30.0‐170.9]). All student subgroups had better PA outcomes when schools provided access to equipment during non‐instructional time. CONCLUSION: There is opportunity to improve student PA through CSH‐guided interventions, but different strategies may be more effective for each gender/grade. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.addbeh.2005.09.011 Byline: Scott T. Leatherdale Keywords: Smoking/tobacco use; Cessation; School-based; Youth/adolescent; Prevention Abstract: The purpose of the present study was to examine characteristics that predict interest in school-based cessation programs among 3136 youth smokers with intentions to quit smoking. The majority of youth smokers report that they would not join a school-based smoking cessation program. However, improving awareness of these types of programs among students is important as sub-populations of youth smokers were more likely to be interested in school-based cessation initiatives when aware that such programs exist. Future school-based cessation intervention outcomes might be improved if programs are targeted to the youth that are most likely to use them, if more youth can be made aware of existing programs, and if the benefits of participating in such programs can be more adequately conveyed to youth smokers. Author Affiliation: Division of Preventive Oncology, Cancer Care Ontario, 620 University Avenue, Toronto ON, Canada M5G 2L7 Department of Health Studies and Gerontology, University of Waterloo, Canada Department of Public Health Sciences, University of Toronto, Canada

Background: In the school year immediately following cannabis legalization in Canada, this paper investigated youth perceptions of school support for the prevention and cessation of substance use. Scant research has examined student perceptions in relation to school disciplinary approaches. This study was the first to classify school discipline approach styles using school-level measures. Objective: The objective of this study was to examine whether different school cannabis use-related disciplinary approaches are associated with student cannabis use and perceptions of school supportiveness for the prevention and cessation of substance use. Results: School- and student-level survey data from Year 7 (the 2018/2019 school year) of the COMPASS study were used, including 68,037 grade 9–12 (Secondary I–V in Quebec) students attending 131 Canadian secondary schools. Schools were classified as using different cannabis use-related disciplinary styles based on school-administrator reported approaches to student first-offense violations of school cannabis policies. We identified that although none of the cannabis use-related disciplinary approach styles examined were associated with cannabis use, they were associated with student perceptions. Students attending schools classified as using a Permissive/Supportive approach had a higher likelihood of perceiving their school as supportive for substance use prevention/cessation than their peers at Authoritarian schools. Students who perceived their school as supportive for substance use prevention/cessation were less likely to report current cannabis use than their peers who perceived their school as unsupportive. Conclusions: Unlike previous studies using school classification styles that are based on student perceptions, results do not support direct associations between school cannabis use-related disciplinary styles and student cannabis use. Future prospective research should examine whether supportive disciplinary approaches (e.g., counseling referrals, educational programs) promote student perceptions of school supportiveness, and in turn, deter student substance use. [ABSTRACT FROM AUTHOR]

The impact of the COVID-19 pandemic on adolescent mental health is a global concern; however, most research is cross-sectional or started after the pandemic response began and thus unable to evaluate within-individual change. The purpose of this prospective study was to evaluate the effect of the initial COVID-19 response on adolescent mental health and ill-health as a natural experiment. We used 3-year linked data from the COMPASS study, including 7,653 Canadian (Quebec, Ontario) adolescents from which 2,099 completed surveys in all three waves (pre-COVID-19 [2018 and 2019] and online [May–July 2020], 2–3 months into the pandemic). A structural equation modeling approach to fixed effects and a difference-in-differences design were used to estimate pre-COVID-19–to–early lockdown change in mental health (psychosocial well-being [flourishing—reverse scored]) and ill-health (depression and anxiety symptoms), compared with 2018-to-2019 change. Models were adjusted for self-selection, age of entry into the cohort, and sociodemographics. Depression, anxiety, and reverse-flourishing scores increased across all waves; however, the mental health changes from the pre-COVID-19 wave (2019) to 2020 were not greater relative to the changes seen across the 2018-to-2019 waves. Our results do not support a detrimental effect of the initial stages of the COVID-19 lockdown measures on adolescent mental health. The deterioration in mental health in the early COVID-19 response was less than the decline found over a prepandemic period. Further prospective research is needed to explore the impact of the prolonged pandemic and related measures on adolescents and inequitable effects in population subgroups. [ABSTRACT FROM AUTHOR]

Introduction: The objectives of this study were to explore the extent to which adolescents adopted COVID-19 preventive measures in the first few months of the pandemic and to understand their adoption by looking at interconnected adoption-related factors and determining the strength of these factors, particularly among subgroups not expected to be early adopters. Methods: Analyses focus on data collected during Spring 2020 from 29 eastern Quebec secondary schools that participated in the COMPASS study. Participants (n = 6052) self-reported their knowledge, perception of risk and preventive practices to do with the COVID-19 pandemic. Data were analyzed using structural equation models based on gender and anxiety level. Results: The majority of respondents reported adopting the recommended COVID-19 preventive measures. The results showed three paths leading to adolescents' adoption of these measures: pandemic knowledge; perception of risk related to COVID-19; and, in particular, discussions with relatives about preventive measures and what to do in case of infection. Conclusions: While most of the adolescent participants in this study appeared to comply with COVID-19 preventive measures, factors such as discussions with relatives emerge as elements to foster in order to improve adolescents' adoption of preventive measures. [ABSTRACT FROM AUTHOR]

Abstract Background Despite the apparent decline in the popularity of roll-your-own (RYO) cigarettes over the past few decades, RYO tobacco products are widely available and used by a substantial number of adult smokers. Considering research has yet to examine the prevalence of RYO tobacco use among youth populations, this manuscript examines the prevalence of RYO tobacco use and factors associated with RYO use in a nationally representative sample of youth smokers from Canada. Methods This study used data collected from 3,630 current smokers in grades 9 to 12 as part of the 2008-09 Canadian Youth Smoking Survey (YSS). Descriptive analyses of the sample demographic characteristics, smoking status, cigarettes per day, weekly spending money, and frequency of marijuana use were examined by RYO tobacco ever use and RYO tobacco current use. Two logistic regression models were used to examine factors associated with RYO tobacco ever use and RYO tobacco current use. Results We identified that 51.2% of current smokers were RYO ever users and 24.2% were RYO current users. The prevalence of RYO current users was highest in Atlantic Canada (40.1%) and lowest in Quebec (12.3%). RYO current users were more likely to be male (OR 1.27), to be daily smokers (OR 1.75), to use marijuana once a month or more (OR 2.74), and to smoke 11 or more cigarettes per day (OR 6.52). RYO current users were less likely to be in grade 11 (OR 0.65) or grade 12 (OR 0.40) and less likely to have between $20 to $100 (OR 0.44) or more than $100 (OR 0.45) of disposable income. Conclusions Developing a better understanding of RYO tobacco use among youth is important for advancing population-level tobacco control prevention strategies and cessation programs. We identified that RYO tobacco use is not a negligible problem among Canadian youth. Ongoing research is needed to continue monitoring the prevalence of RYO use among youth and the factors associated with its use, but to also monitor if this more affordable tobacco product is being targeted to price sensitive youth smokers.

Background: Existing research suggests positive correlations between screen time sedentary behaviors (STSB) and substance use, including cannabis use, among youth. However, little research has examined what factors mediate these relationships. Methods: This study examined mediating pathways among STSB, internalizing symptoms (IS), and cannabis use in a linked longitudinal sample of 28 269 Canadian youth who participated in the COMPASS study over a two-year period (2017/18 to 2018/19). Structural equation modeling examined two main hypotheses cross-sectionally and over time: 1) if IS mediated associations between STSB and cannabis use frequency, and 2) if STSB mediated associations between IS and cannabis use frequency. Results: Results demonstrated significant partial mediation effects for both hypotheses. For example, indirect effects indicated that IS mediated the association between STSB and cannabis use both cross sectionally (95% CI: 0.021, 0.029) and longitudinally (95% CI: 0.006, 0.010). STSB also mediated associations between IS and cannabis use cross sectionally (95% CI: 0.015, 0.023) and longitudinally (95% CI: 0.010, 0.014). This study demonstrated that the associations between STSB, internalizing symptoms and cannabis use are complex, involving mediation in both directions. Discussion: These findings can be used to inform public health initiatives that aim to take a comprehensive approach to addressing negative health behaviors and outcomes, as it is clear that the multi-directional relationships between STSB and mental health may in-turn impact other health behaviors. Future research should continue to examine mediating factors between STSB and substance use among youth, including exploration of associations with other substances. Supplemental data for this article is available online at https://doi.org/10.1080/10826084.2021.1922455. [ABSTRACT FROM AUTHOR]

Research has indicated that cannabis consumption through alternative modes of use such as eating/drinking or vaping may be increasing in areas where cannabis has been legalized. However, there is little research that examines these different modes of cannabis use in a Canadian youth context. The purpose of this study was to identify pre-legalization modes of cannabis use (smoking, eating/drinking, vaping) among a sample of 45,677 secondary school students who participated in year 6 (2017/18) of the COMPASS study. Within our sample, 24.9% reported cannabis use within the last 12 months; among those, 38.7% reported occasional use, and 61.3% reported current use. Multi-mode patterns of use were common; more than half of those reporting current cannabis use indicated a use pattern other than exclusively smoking, and over 20% reported use via all three modes. Findings from a latent class analysis identified three distinct groups and suggested that eating/drinking cannabis and vaping cannabis may more often be an addition to smoking rather than a replacement. Continued monitoring of these patterns is important for public health and necessary to evaluate any changes resulting from cannabis legalization. [ABSTRACT FROM AUTHOR]

Latent class analysis was performed to identify clusters of items on the Longitudinal Study of Adolescent Health – School Connectedness Scale among students. Cluster membership was explored by student-reported ethnicity. The sample included students attending Canadian secondary schools in two waves of the COMPASS study: Years 4 (Y4:2015/16) (N=40,436) and 7 (Y7:2018/19) (N=60,610). Results were comparable across waves. Four clusters resulted: strongly connected (Y4 66.6%; Y7 67.9%), socially disconnected (14.1%; 15.2%; perceptions of equitable treatment but lacking feelings of belonging), social belonging (11.9%; 10.3%; feelings of being part of their school and close to others, but less likely to perceive equitable treatment), and weakly connected (7.4%; 6.6%). White and Asian students were more likely to be 'strongly connected', while Black and 'other' or mixed ethnicity students were overrepresented in the 'weakly connected' and 'social belonging' clusters. Cluster variations merit attention to improve how racialized and ethnic minority youth experience school environments. [ABSTRACT FROM AUTHOR]

Objective: To investigate demographic and behavioral risk factors for non-medical use of prescription opioids. Methods: Canadian high school students taking part in the COMPASS study reported non-medical use of prescription opioids in three categories (oxycodone, fentanyl, other prescription pain relievers) in 2017/2018. Factors of interest were collected at two baselines (2016/2017; 2015/2016) and included validated demographic (age, gender, race/ethnicity, spending money), substance use (alcohol, tobacco, cannabis), and school-related (connectedness, homework completion, truancy) measures. Results: In total, 18,826 and 7,967 students were linked between 2017/2018 and 2016/2017 or 2015/2016 respectively. Use of fentanyl was least prevalent (0.7% and 1.0% respectively), with the use of oxycodone (1.7% and 1.9%) more and use of other prescription pain relievers (4.9% and 5.1%) most common. Male gender, substance use, and lack of homework completion were associated with the use of oxycodone and other prescription pain relievers. School connectedness was identified as a potential protective factor. Conclusions: Two-thirds of significant associations found were present only in one of the two models, highlighting the complexity of non-medical use of prescription opioids among youth. School connectedness may lower the risk of non-medical use of prescription opioids, indicating that a school-based focus is justified. [ABSTRACT FROM AUTHOR]

Introduction: Following cannabis legalization in Canada, a better understanding of the prevalence of unprompted cannabis use reduction and subsequent effects on youth academic outcomes is needed to inform harm reduction and health promotion approaches. Methods: We analyzed a longitudinally linked sample (n = 91 774) from the COMPASS prospective cohort study of Canadian high school students attending Grades 9-12 in Ontario and Alberta between 2013-2014 and 2016-2017. We investigated the prevalence of spontaneous cannabis use reduction and cessation between grade transitions (Grades 9-10, 10-11, 11-12) and the effect of cessation on academic achievement (current or recent math and English course marks) and rigour (usual homework completion and past-month truancy). Results: Only 14.8% of cannabis users decreased their use between grades. Of these, two-thirds made only incremental downward changes, a pattern which held true for all three transitions. Cessation rates from daily and weekly use decreased every year. After cessation, students had better odds than continuing users (OR = 1.23, 95% CI: 1.03-1.48) and worse odds than never-users (OR = 0.55, 95% CI: 0.31-0.97) for some subcategories of math performance. Students who quit cannabis universally improved class attendance (OR = 2.48, 95% CI: 1.93-3.19) and homework completion (OR = 2.32, 95% CI: 1.85-2.92) compared to continuing users. Conclusion: Increased academic rigour may underlie any improvements seen in academic performance after cannabis cessation. High school students who use cannabis likely need targeted support to facilitate reduction or cessation and subsequent academic recovery. This indicates that a school-based focus on cannabis harm reduction is justified. [ABSTRACT FROM AUTHOR]