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We quantified the joint evolution of sleep duration and screen time between 2018 and 2022 in a large sample of adolescents from Quebec, Canada, to ascertain changes that occurred during the COVID-19 pandemic. A natural experiment design was used to compare variations from year to year and in association with the pandemic outbreak. Using structural equation modeling on data collected between 2018 and 2022 among adolescents attending 63 high schools, we analyzed the joint evolution of sleep duration and screen time while adjusting for previous year values, concurrent flourishing score, sex, age, and family level of material deprivation. A total of 28,307 adolescents, aged on average 14.9 years, were included in the analyses. Between 2019 and 2022, sleep duration increased by 9.6 (5.7, 13.5) minutes and screen time by 129.2 (120.5, 138.0) minutes on average. In 2022, the adolescents spent almost equal amounts of time sleeping and using screens. Lower flourishing scores were associated with shorter sleep duration and lengthier screen time. Girls' screen time became similar to boys' over time. Adolescents now spend almost equal amounts of time sleeping and using screens, a situation that calls for urgent public health actions. These findings highlight the importance of tracking changes in adolescents' behaviours over time, to design and implement interventions adapted to the changing health needs of different groups. [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]

There is concern over the potentially detrimental impact of the COVID-19 pandemic on adolescents' mental health. We examined changes in depression and anxiety symptoms from before (2018-19) to the early (2019-20) and ongoing pandemic (2020-21) responses among Canadian adolescents in the context of a natural experiment. We used linked survey data from 5,368 Canadian secondary school students who participated in three consecutive waves of the cannabis use, obesity, mental health, physical activity, alcohol use, smoking, and sedentary behaviour study during the 2018-19, 2019-20, and 2020-21 school year. Separate fixed effects models examined whether changes in depression (Center for Epidemiologic Studies Depression Scale Revised-10) and anxiety (General Anxiety Disorder-7) symptoms differed between two cohorts. The cohorts differed in the timing of their second data collection wave; one cohort participated before the pandemic and the other cohort participated in the early pandemic (spring 2020). Depression and anxiety symptoms increased during the early and ongoing pandemic periods in the overall sample and both cohorts. The two cohorts experienced similar elevations in their symptoms. Females and younger respondents presented greater elevations over time. The proportion of adolescents with significant depressive (29.4%) and moderate-to-severe anxiety (17.6%) symptoms at baseline increased by 1.5 times, reaching 44.8% and 29.8% in the ongoing pandemic period, respectively. Findings suggest that internalizing symptoms have consistently increased since before the onset of COVID-19, particularly in the ongoing pandemic period; however, we found no evidence of the increase being due to the pandemic in the early COVID-19 period when comparing the two cohorts. Ongoing evaluation of adolescents' mental health is necessary to capture potentially dynamic impacts over time. [ABSTRACT FROM AUTHOR]

To determine if income inequality at the census division level is associated with alcohol consumption and abuse among junior high and high school students. Data on adolescents are from the Cannabis use, Obesity, Mental health, Physical activity, Alcohol use, Smoking, and Sedentary behavior (COMPASS) study. Participant data (n = 19,759) were collected during three survey waves (2016–2017, 2017–2018, and 2018–2019) and linked to 30 census divisions within four Canadian provinces. Data on income inequality and other area-level factors were derived from the 2016 Canadian census. Multilevel logistic regression modelling was used to quantify the associations between income inequality, monthly alcohol consumption, and binge drinking. After adjusting for covariates, students living in census divisions within the second and third quintiles of income inequality experienced an average 80% (OR = 1.80, 95% CI = 1.08–3.02) and 92% (OR = 1.92, 95% CI = 1.05–3.51) increased odds of engaging in monthly binge drinking, respectively, compared to those living in the first quintile. Similarly, adolescents living in census divisions within the second inequality quintile experienced an average 169% (OR = 2.69, 95% CI = 1.45, 4.99) increased odds of engaging in weekly binge drinking, compared to those living in the first quintile. There was no significant association between higher income inequality and current monthly alcohol consumption. Moderate area-level income inequality within census divisions was adversely associated with alcohol consumption among adolescents. Future work should investigate the potential mechanisms that mediate this relationship. [ABSTRACT FROM AUTHOR]

Depression and anxiety among adolescents are major public health concerns. Findings indicate that income inequality was associated with increased risk for depression and anxiety among adolescents; however, this has not been tested longitudinally. We aim to quantify the longitudinal association between income inequality and depression and anxiety among Canadian adolescents. We used longitudinal data on 21,141 students from three waves (2016/17–2018/19) of the Cannabis, Obesity, Mental health, Physical activity, Alcohol, Smoking, and Sedentary behavior (COMPASS) school-based study. Multilevel modeling was used to assess the association between census division (CD)-level income inequality and depressive and anxiety symptoms and odds for depression and anxiety over time. Across CDs, the mean Gini coefficient was 0.37 (range: 0.30, 0.46). Attending schools in CDs with higher levels of income inequality was associated with higher depressive scores (ß = 0.08; 95% confidence interval [CI] = 0.02, 0.14) and an increased odds for depression (odds ratio = 1.55, 95% CI = 1.06, 2.28) over time. Income inequality was not significantly associated with anxiety symptoms or experiencing anxiety over time. Additional analyses showed that income inequality was associated with higher depressive scores among females (ß = 0.10; 95% CI = 0.01, 0.18) and males (ß = 0.08, 95% CI = 0.01, 0.15) and for anxiety scores among females (ß = 0.13, 95% CI = 0.04, 0.22), but not among males (ß = −0.01, 95% CI = −0.09, 0.06). Findings from this study indicated that income inequality is associated with depression over time among adolescents. This study highlights key points of intervention for the prevention of mental illness in adolescents. [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]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.addbeh.2009.10.013 Byline: Rovshan M. Ismailov (a), Scott T. Leatherdale (a)(b)(c) Keywords: Former smokers; Nicotine replacement therapy; Pharmaceutical aid Abstract: There is a need to better understand the prevalence of use of pharmaceutical aids among former smokers, and explore concerns that those former smokers may have had about using such products. This paper examines the use of various cessation aids and strategies as well as reasons for not using cessation aids among a nationally representative sample of former smokers from Canada. Author Affiliation: (a) Department of Population Studies and Surveillance, Cancer Care Ontario, Canada (b) Department of Health Studies and Gerontology, University of Waterloo, Canada (c) Dalla Lana School of Public Health, University of Toronto, Canada

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

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.addbeh.2005.10.003 Byline: Scott T. Leatherdale (a)(b)(c), Steve Manske (b)(d), Christina Kroeker (b) Keywords: Smoking behaviour; Youth/adolescence; Peer influences; School environment; Multi-level/hierarchical; Sex/gender differences Abstract: The purpose of this study was to examine sex differences in how the smoking behaviour of close friends and older peers at school influence smoking onset and progression among 10,843 grade 9, 10 and 11 students from 29 secondary schools in Ontario, Canada. In lower-risk student populations (i.e., students with no smoking friends or one smoking friend), males and females were both at a similar level of risk for occasional smoking as a function of the smoking rate of older students at their school. Among higher-risk student populations (i.e., students with three or more close friends who smoke), the smoking rate of older students at school did not influence the risk of occasional smoking. The odds of a female student being a regular smoker increased as the prevalence of smoking among older students at her school increased regardless of her close friends' smoking behaviour. However, among male students, the influence of older student smoking at school on the odds of regular smoking was moderated by the number of close friends who smoke. It appears that the prevalence of older student smoking at a school is more influential among younger female students, whereas the smoking behaviour of close friends appears to be more influential among younger male students. This new finding provides unique insight for tailoring and targeting future school-based smoking prevention initiatives. Author Affiliation: (a) Division of Preventive Oncology, Cancer Care Ontario, Canada (b) Department of Health Studies and Gerontology, University of Waterloo, Canada (c) Department of Public Health Sciences, University of Toronto, Canada (d) Centre for Behavioural Research and Program Evaluation for the National Cancer Institute of Canada and the Canadian Cancer Society, Canada

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.addbeh.2005.02.004 Byline: Scott T. Leatherdale (a)(b), Paul W. McDonald (b)(c) Keywords: Cessation; Youth; Intervention Abstract: The purpose of this study was to examine the attitudes of youth smokers toward nine common smoking cessation approaches. Attitudes were examined among 3660 youth smokers who intended to quit smoking. The majority of youth smokers report that they would never use the smoking cessation approaches that are commonly recommended for youth populations. The approaches that were appealing to youth are quitting on their own and using the advice of friends. Future initiatives need to more effectively communicate to youth the benefits of existing cessation approaches, make existing interventions more appealing, or develop new approaches that address youth needs. Author Affiliation: (a) Division of Preventive Oncology, Cancer Care Ontario, 620 University Avenue, Toronto ON, Canada M5G 2L7 (b) Department of Health Studies and Gerontology, University of Waterloo, Canada (c) Health Behaviour Research Group, University of Waterloo, Canada

Those born earlier within cohorts of similarly aged children tend to outperform peers in athletic and academic pursuits. Subsequent evidence suggests relatively younger children may also experience worse emotional and psychosocial health; however, evidence from middle adolescents is limited. This study assessed whether depression, anxiety, and psychosocial well-being differed by the relative birth quarter (RBQ) within a cohort of grades 9–12 in secondary schools across Canada. Data from the 2018–19 student self-report surveys of the cannabis use, obesity, mental health, physical activity, alcohol use, smoking, and sedentary behavior study were analyzed. Students having made normative progress were categorized into RBQs by the provincial enrollment cutoff date (n = 49,921). Hierarchical modeling approaches assessed whether self-reported depression, anxiety, psychosocial well-being, and positive controls differed by RBQ after controlling for covariates. Despite relative age effects for positive control outcomes, no significant difference was detected for anxiety and depression scores or likelihood of meeting thresholds for having clinically relevant symptoms. However, a significant difference emerged between RBQs for psychosocial well-being scores; post hoc tests found that psychosocial well-being scores were lower in the fourth RBQ than those in all prior quarters. Results agree with limited findings that relative age differences in emotional health are not significant in older cohorts. Nonetheless, relatively older individuals reported very small (d =.04–.05) advantages in psychosocial well-being than their youngest peers, which aligns with previous data. Longitudinal approaches to assess relative age effects on mental health during and throughout the transition into middle adolescence are warranted. [ABSTRACT FROM AUTHOR]

Objectives: Muscle-strengthening activity (MSE e.g. push-ups, sit-ups, use of weight machines) is linked to multiple health benefits for youth, and is part of the global physical activity guidelines for children and adolescents (5-17 years). However, MSE is rarely assessed in youth health surveillance. This study describes the longitudinal trends and predictors of MSE among a cohort of Canadian youths.Design: Longitudinal.Methods: Data were drawn from a cohort of 3366 youths who participated in three waves of COMPASS, a longitudinal study of secondary school students across Canada [Wave 1 (T1) 2015/16, Wave 2 (T2) 2016/17, Wave 3 (T3) 2018/19]. The prevalence of the sample meeting the MSE guideline (≥3 days/week) was calculated for each wave. A multivariable logistic regression assessed the odds of meeting the MSE guideline for each wave (T1 and T2 and T3) across sociodemographic/lifestyle characteristics (e.g. sex, race, regionally, Body Mass Index, and aerobic physical activity).Results: For the total sample, MSE guideline adherence significantly declined across each study wave (T1 = 57.0%; T2 = 52.0%; T3 = 48.5%; p < 0.001 for linear trend). Population sub-groups less likely to meet the guideline at each wave included females, youth who were underweight or obese, those reporting insufficient aerobic physical activity, those from large urban settings, and youth who identify as Asian.Conclusions: Among a large sample of Canadian youths, approximately half met the MSE guideline, with this prevalence declining over time. Large-scale MSE interventions are needed to address the low and decreasing adherence to this key modifiable health-related behavior among Canadian youths. [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]

• Movement behaviours consisted of sleep, physical activity, and screen time. • Mental health measures included flourishing, resiliency, anxiety and depression. • Best day scenarios maximized sleep and physical activity while minimizing screen. • For transgender youth small difference in activity associated better mental health. • Screen use associated with less severe poor mental health in boys. [ABSTRACT FROM AUTHOR]

ABSTRACT Purpose Cross-sectional evidence suggests that school connectedness is an important correlate of health-related behaviors among adolescents, but prospective studies are needed to strengthen the case for a causal relationship. This study investigated the prospective relationship between school connectedness and four health-related behaviors: cigarette smoking, marijuana use, binge drinking, and physical activity. Methods We analyzed 4 years of data from the COMPASS study. Participants included in this analysis were 33,313 students who provided information on sociodemographic, school connectedness, and the four health-related behaviors for at least two consecutive years. Generalized Estimating Equation models were used to examine whether the change in school connectedness scores predicted the change in an individual child's trajectory of health-related behaviors across 9th, 10th, 11th, and 12th grades. Results As students moved to higher grades, school connectedness decreased, and the likelihood of being a less frequent smoker, marijuana user, and binge drinker, and meeting physical activity guidelines declined. An increase in school connectedness scores was associated with an increased likelihood of meeting physical activity recommendations (OR = 1.06, p <.01), being a less frequent smoker, marijuana user, and binge drinker (OR = 1.30, 1.17, 1.10, respectively; p 's <.0001) across the 4 years. Conclusions : This study provides prospective evidence supporting the protective effects of school connectedness on substance abuse and physical activity, and highlights the importance of fostering school connectedness to support healthy adolescent development. [ABSTRACT FROM AUTHOR]

Trauma is commonly overlooked or undiagnosed in clinical care settings. Undetected trauma has been associated with elevated substance use highlighting the need to prioritize identifying individuals with undetected trauma through common characteristics. The purpose of this study is to identify classifications of traumatic life experiences and substance use among persons admitted to inpatient psychiatry in Ontario and to identify covariates associated with classification membership. A population-based retrospective cohort study was conducted using interRAI Mental Health (MH) assessment data. Individuals were included who experienced traumatic life events (N = 10,125), in Ontario, Canada between January 1, 2015, to December 31, 2019. Eight latent classes were identified that ranged from low (i.e., Class 1: Interpersonal Issues, Without Substance use) to high (i.e., Class 8: Widespread Trauma, Alcohol & Cannabis Addiction) complexity patterns of traumatic life events and substance use indicators. Classifications with similar trauma profiles were differentiated by patterns of substance use. For example, individuals in Class 2: Safety & Relationship Issues, Without Substance use and Class 3: Safety & Relationship Issues, Alcohol & Cannabis both had many estimates centered around the experience of victimization (e.g., victim of sexual assault, victim of physical assault, victim of emotional abuse). Multinomial logistic regression models highlighted additional factors associated with classifications such as homelessness, where those who were homeless were 2.09–4.02 times more likely to be in Class 6: Widespread Trauma & Substance Addiction. Trauma exposures are complex and varied among persons in inpatient psychiatry and can be further differentiated by substance use patterns. These findings provide a population-based estimate of the trauma experiences of persons in inpatient settings in Ontario, Canada. Findings demonstrate the importance of using comprehensive assessment to support clinical decision making in relation to trauma and substance. [ABSTRACT FROM AUTHOR]

Purpose Use of e-cigarettes by youth is proliferating worldwide, but little is known about the behavioral profile of youth e-cigarette users and the association of e-cigarette use with other health-risky behaviors. This study examines the associations between e-cigarette use and tobacco, marijuana, and alcohol use among a large sample of Canadian youth. Methods Using Canadian data from 39,837 grade 9 to 12 students who participated in year 3 (2014–2015) of the COMPASS study, logistic regression models were used to examine how current use of e-cigarettes were associated with tobacco, marijuana, binge drinking, and energy drinks mixed with alcohol. Pearson's chi-square tests were used to examine subgroup differences by sex. Results Overall, 9.75% of respondents were current e-cigarette users. Current cigarette smokers (odds ratio [OR] = 3.009), current marijuana users (OR = 5.549), and noncurrent marijuana users (OR = 3.653) were more likely to report using e-cigarettes than noncigarette smokers and nonmarijuana users. Gender differences among males and females showed higher risk of e-cigarette use among female current marijuana users (OR = 7.029) relative to males (OR = 4.931) and female current smokers (OR = 3.284) compared to males (OR = 2.862). Compared to nonbinge drinkers, weekly (OR = 3.253), monthly (OR = 3.113), and occasional (OR = 2.333) binge drinkers were more likely to use e-cigarettes. Similarly, students who consume energy drinks mixed with alcohol (OR = 1.650) were more likely to use e-cigarettes compared to students who do not consume them. Conclusions We identify that youth who binge drink or use marijuana have a greater increased risk for using e-cigarettes compared to cigarette smokers. These data suggest that efforts to prevent e-cigarette use should not only be discussed in the domain of tobacco control. [ABSTRACT FROM AUTHOR]

Through a range of hypothetical mechanisms physical activity may provide benefits in the prevention of substance use across the lifespan. The primary objective of this study was to evaluate the prospective association between physical activity and the initiation of current substance use among youth. The secondary objective examined if school connectedness mediated any prospective association. This longitudinal study included grade 9–12 students (n = 3244) with three years of linked data (2017–2020) from the COMPASS study. Multi-level logistic regressions were built to explore the association between changes in physical activity (meeting MVPA guidelines, outside of school sport participation, competitive school sport and non-competitive school sport) and the initiation of current substance use behaviours (cigarette, e-cigarettes, cannabis and binge drinking). Analyses examined if school connectedness mediated the association between physical activity and substance use. Results indicated that females who initiated 60 min of MVPA daily had greater than three times the odds of initiating current cigarette smoking (OR = 3.26 [1.45, 7.33]). Additionally, males who consistently participated in outside-of-school sport had greater than two times the odds of initiating current binge drinking (OR = 2.28 [1.43, 3.63]). Our mediation analysis demonstrated that sport participation may lower current e-cigarette and cannabis use through school connectedness. Overall, there was no evidence that physical activity confers broad, universal benefits in preventing substance use among Canadian youth. However, this is the first work to indicate that sport participation may provide a contextual experience that enhances school connectedness which in turn is associated with substance use prevention. • Physical activity was positively associated with the initiation of current cigarette and binge drinking. • Sport participation may lower substance use through school connectedness. • This work highlights a more central role for school connectedness in preventing substance use among youth. [ABSTRACT FROM AUTHOR]

Introduction: The purpose of this study was to examine the correlates of current smoking among off-reserve First Nations and Métis adults, two Aboriginal Canadian groups that are at higher risk to smoke and more likely to suffer from chronic health conditions relative to their non-Aboriginal counterparts. A particular focus was on culturally specific factors and their associations with current smoking.Methods: We used data from Statistics Canada's, 2012 Aboriginal Peoples Survey to investigate the correlates of smoking among 12,720 First Nations and Métis adults. Sequential binary logistic regression models were estimated to examine associations between smoking and culturally specific, demographic, geographic, socioeconomic and health-related variables.Results: Overall, 39.4% were current smokers. Multivariate results found that those who had hunted, fished or trapped within the last year were more likely to be smokers. In addition, respondents who were exposed to an Aboriginal language at home or outside the home were more likely to be smokers. Current smoking was significantly associated with being aged 35 to 49 years, living in a small population center, low income, low education, unemployment, being unmarried, low ratings of self-perceived health, heavy drinking and low body mass index. Respondents aged 65 years and older and those living in British Columbia were less likely to smoke.Discussion: The results of this study suggest that it may be useful to consider cultural characteristics, particularly language in efforts to reduce the prevalence of manufactured tobacco use among First Nations and Métis adults. Interventions should also consider demographic, geographic and socioeconomic variables, in addition to co-occurring health-risk behaviors. [ABSTRACT FROM AUTHOR]

The impact of COVID-19 on adolescent mental health is a global concern. Increased screen time and reduced physical activity due to the lockdown measures have been linked to detrimental mental health outcomes; however, the literature remains limited by cross-sectional and retrospective designs, and consideration of behaviours in isolation. Prospective evidence is necessary to examine whether moderate-to-vigorous physical activity (MVPA), sleep and screen time influenced changes in mental health. Analyses used data from a prospective cohort study of secondary school students in Canada with baseline data from the 2018–2019 school year and linked follow-up data from online surveys completed during the initial COVID-19 outbreak (May–July 2020). Multilevel linear regression models were used to evaluate the within- and between-person isotemporal substitution effects of sleep, MVPA and screen time behaviours on depression, anxiety, subjective well-being, and trait emotional dysregulation. Linked longitudinal data from 2645 students attending 44 schools were available. Between-person effects indicated that individuals who engaged in more MVPA and sleep while minimizing screen time had lower depression scores, less severe emotional dysregulation, and better subjective well-being. While controlling for between-person effects, within-person year-on-year change suggests those who increased screen time while decreasing either MVPA or sleep experienced mental health decline on all outcomes. MVPA and sleep were associated with youth mental health during the early COVID-19 lockdown. Increasing MVPA and sleep (or at least mitigating the increase of screen time) compared to the prior year was associated with better mental health during the early pandemic. A limitation to consider is that the screen time measure represents a combination of screen behaviours, and effects of replacing screen time may have varied if distinctions were made. • Individuals accruing more sleep or physical activity had better mental health status. • During COVID-19 school closures, those who maintained/improved habits faired best. • Sacrificing sleep/physical activity for screen time was related to negative health changes. [ABSTRACT FROM AUTHOR]

Highlights: [•] Co-SEA as a app supported by all major mobile device platforms. [•] Archives photos of the built environment features being measured in the audit. [•] Can collect and store information without an internet connection. [•] Audit data can be uploaded to a secure server via a Wi-Fi connection. [•] Co-SEA can be easily shared and used with other researchers. [ABSTRACT FROM AUTHOR]

Abstract: Patterns of smoking can vary among youth smokers. The purpose of this study was to examine three different patterns of smoking among youth (daily smoking, smoking sporadically on weekdays and weekends, and smoking during weekdays only), and to examine the sociodemographic characteristics that are associated with each smoking pattern in a representative sample of Canadian youth smokers. Data were collected as part of the 2010/2011 Youth Smoking Survey (YSS) from 31,396 students in grades 9 to 12 from secondary schools in 9 Canadian provinces. Data from the YSS were used to assess smoking behaviors and sociodemographic factors that are associated with smoking patterns among youth. We used logistic regression models to examine factors associated with week day only and some day smoking patterns relative to daily smoking patterns. Results indicate that among current youth smokers, the majority are daily smokers (62.0%), followed by some day (23.5%) and week day only (13.5%) smokers. Students who smoke some days were more likely than daily smokers to share cigarettes with others; however, they were less likely than daily smokers to have a parent, step-parent or guardian who smokes cigarettes and less likely to have close friends who smoke cigarettes. Conversely, students who smoke week days only were less likely than daily smokers to have a sibling who smokes cigarettes. These data suggest that the school environment continues to play an important role in reducing youth smoking rates in Canada, especially among youth who only smoke week days. The high percentage of week day only smokers suggests that current school-level tobacco control initiatives may be insufficient for preventing youth smoking onset. [Copyright &y& Elsevier]

Abstract: Background: Research indicates that it is common for youths to use nicotine replacement therapy (NRT) despite limited empirical evidence for its effectiveness within this population. Since very little is known about the characteristics associated with NRT use by youth, the current study examined the association between ever and current use of NRT as a function of student characteristics and the characteristics of the schools they attend. Methods: This study used nationally representative student-level data from 29,296 grade 9 to 12 students who participated in the 2008–2009 Canadian Youth Smoking Survey (YSS). School-level data on the built environment surrounding schools were provided by DMTI-Spatial, and data on school location were provided by the Canadian Census. Two multilevel logistic regression models were used to predict ever use of NRT and current use of NRT as a function of student and school characteristics among current smokers. Results: Overall, 21.1% of youth smokers in Canada had ever used NRT and 5.1% were currently using NRT. Odds of ever and current NRT use were highest among daily smokers and boys, while youths who had made multiple quit attempts or participated in a quit and win contest were more likely to be ever NRT users. Attending a school located within an urban area increased youths'' odds of ever and current NRT use, whereas higher density of pharmacies surrounding a school was inversely associated with current NRT use. Conclusions: Characteristics of students and the schools they attend were associated with the likelihood of youth smokers using NRT. Significant between-school differences in NRT use exist, however further research is needed to identify which school characteristics account for these differences and understand how youth are accessing NRT. [Copyright &y& Elsevier]

The current study examined the prevalence of alcohol, tobacco and drug use and comorbid use of these substances among 45,425 students in grades 7 to 12 as part of the 2008–09 Canadian Youth Smoking Survey. The results of this paper suggest that alcohol, tobacco, marijuana and illicit drugs are currently used by a substantial number of youth in Canada, and that comorbid use is also very widespread among users. Alcohol was the most prevalent substance used by youth and it was rare to find youth who had used tobacco or drugs without also currently using alcohol. By grade 12, the majority of students were current users of alcohol, tobacco or drugs. Future research should consider developing a better understanding of how to prevent substance use among this population. [Copyright &y& Elsevier]

Abstract: Understanding factors associated with youth cigarette access behaviours can provide insight into the development of more effective means of preventing youth from accessing cigarettes. This cross-sectional study used self-reported data collected from 41,886 students in grades 9 to 12 who participated in the 2006–07 Youth Smoking Survey to examine the student- and school-level characteristics that differentiate youth smokers who usually access cigarettes from a social source versus buying their own from retailers. Multi-level regression analyses revealed significant between-school variability in the odds of a smoking student reporting that they usually buy their own cigarettes. Important student-level characteristics associated with how youth usually access their cigarettes included binge drinking and being asked for age or photo identification when purchasing cigarettes from a retailer. Future studies should further explore the school- and student-level characteristics associated with youth cigarette access behaviour. [Copyright &y& Elsevier]

Abstract: Purpose: Sedentary behavior research typically only examines screen time activities and not communication time activities, such as talking on the phone, texting, or instant messaging. Methods: Data from 2,449 grade 5 to 8 students were used to examine factors associated with the time youth spent in communication-based sedentary behaviors. Results: Screen time, physical activity, grade, and gender were associated with moderate and high communication time. Discussion: Future research on sedentary behavior should include measures of communication time. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: It has been suggested that health benefits from physical activity may be accrued through active commuting to school. Considering that active commuting is modifiable via policy and that there is limited research examining active commuting among high school students, this is a domain that warrants further investigation. The purpose of this study is to explore the relationships between demographic, behavioral, social/psychological, and environmental correlates of active commuting to school among a sample of high school students. Methods: Students (N = 21,345) from 76 Ontario high schools (grades 9–12) completed the School Health Action, Planning and Evaluation System Physical Activity Module between 2005–2006. Demographic (gender, grade, body mass index), behavioral (smoking status, physical activity, sedentary time), social/psychological (perceived athletic ability, weight status, parental encouragement), and environmental (school location, type, weather) predictors of active commuting (daily or mixed mode) were assessed. Results: Only 42.5% of high school students reported actively commuting to school. Students were less likely to actively commute to school if they were girls, in grade 12, smoked daily, were low–moderate in physical activity, or attended a rural school. Conclusions: Patterns of active commuting to school are influenced by multiple factors, some of which are modifiable through intervention. This has important implications for future school-based programming designed to enhance health and physical activity of adolescents through using active modes of transportation to school. [Copyright &y& Elsevier]

Abstract: Purpose: To examine how smoking behaviour and beliefs, physical activity and weight, and social influences are associated with intentions to quit smoking among youth. Methods: This cross-sectional study used self-reported data collected from 26,379 grade 9 to 12 students in Ontario, Canada. Results: Intending to quit smoking was positively associated with students believing that they could quit smoking, being moderately active, and having smoking friends. Male smokers were less likely to intend to quit smoking than female smokers. Intending to quit smoking in the next 30 days was positively associated with students believing that they could quit smoking and being highly active, and negatively associated with being overweight and having three or more smoking friends. Conclusion: These findings provide insight for researchers and practitioners interested in understanding the factors which may promote smoking cessation among smoking school-aged populations. [Copyright &y& Elsevier]

Abstract: Purpose: To examine how social models in the school environment and individual student characteristics are related to smoking susceptibility. Methods: Using data from the School Smoking Profile Project, multi-level logistic regression analysis was used to identify school and student characteristics related to smoking susceptibility among 6679 never smokers from 29 secondary schools in Ontario, Canada. Results: If a nonsmoking student attended a school where there was student smoking on the school periphery, he or she was less likely to be susceptible to smoking (OR 0.71, 95% CI 0.57–0.89). A significant contextual interaction between the smoking on the school periphery and friends’ disapproval of smoking was identified (β = 0.68 [0.23], p &#60; .01]; students with friends who disapprove of smoking were more likely to be susceptible to smoking if they attended a school with student smoking on the school periphery. Conclusion: Nonsmoking students who attend a school with student smoking on the school periphery are at an increased risk for being susceptible to smoking if they have friends who disapprove of smoking. Future school-based smoking prevention programs might benefit from targeting both individual students and entire schools with programming activities. [Copyright &y& Elsevier]

Purpose The purpose of this study was to examine the use of conventional and alternative tobacco and nicotine products among secondary school students. Methods Respondents were 44,163 grade 9–12 students who participated in Year 2 (2013–2014) of COMPASS, a cohort study of 89 purposefully sampled secondary schools in Ontario and Alberta, Canada. Past-month use of various tobacco and nicotine products was assessed, as well as correlates of use, using a generalized linear mixed effects model. Results Overall, 21.2% of the sample reported past-month use of any tobacco or nicotine product, with 7.2% reporting past-month use of e-cigarettes. E-cigarette users reported significantly greater prevalence of current use for all products. Students who were male, white, had more spending money, and had a history of tobacco use were more likely to report past-month use of e-cigarettes. Conclusions Approximately one fifth of youth reported past-month use of a nicotine product, with e-cigarettes being the third most common product. Overall, the findings suggest a rapidly evolving nicotine market. [ABSTRACT FROM AUTHOR]

• Emerging adults (EAs) often engage in risky behaviors. • Habitual and casual cannabis use are associated with traffic violations among EAs. • This association is moderated by age and use of other drugs. • Research on effects of tolerance among habitual EA users of cannabis is warranted. While some research has shown that cannabis use can impair driving ability, evidence to the degree and impact of impairment are lacking. This study examined the association between habitual or casual cannabis use and past-year traffic violations among emerging adults (EAs). Data come from the 2012 Canadian Community Health Survey–Mental Health. Respondents (n = 5630) were categorized as: early (15–19 y), middle (20–24 y), and late (25–29 y) EAs. Traffic violations were measured using self-report and cannabis use was measured using the WHO Composite International Diagnostic Interview. The prevalence of traffic violations was higher for males (19.2 %) vs females (9.9 %) and middle (16.2 %) and late (19.4 %) EAs vs early (8.8 %) EAs. The odds of reporting traffic violations were higher for EAs who engaged in habitual [OR = 1.77 (1.17–2.67)] or casual [OR = 1.79 (1.27−2.51)] cannabis use when compared to non-users. Age moderated the association such that higher odds of traffic violations were reported in early EAs who were casual cannabis users and middle EAs who were habitual or casual cannabis users when compared to non-users. Use of other drugs was also a moderator—in the absence vs. presence of other drug use, odds of traffic violations were higher in those who engaged in either habitual or casual use of cannabis. When accounting for the moderating effects of age and drug use, habitual and casual cannabis use resulted in increased odds of a traffic violation. Future research is warranted to explore the robustness of our findings. [ABSTRACT FROM AUTHOR]

Physical activity, sedentary behavior, and sleep are associated with mental health in adolescents. Mental health may depend not only on the amount of time spent in a specific activity, but also on the activity it displaces. The aim of this study was to examine the impact of reallocating 15 min of time spent in one health behavior with 15 min in another on adolescent mental health. Cross-sectional data from the students participating in the COMPASS Study (2018–2019) were analyzed (N = 46,413). Participants self-reported the amount of time they spent engaged in moderate-to-vigorous physical activity (MVPA), doing homework and using screens, and their sleep duration on average each day, depressive symptoms, anxiety, and flourishing. Data were analyzed using isotemporal substitution modeling. Among adolescents getting less than the recommended amount of sleep, replacing any behavior with sleep was generally associated with better mental health outcomes. Conversely, among adolescents getting adequate sleep, the findings did not support replacing other behaviors with sleep with the exception of screen time. Replacing homework and MVPA with sleep was associated with less flourishing regardless of sleep duration. Replacing screen time with any behavior may be better for mental health outcomes. Results provide further support for the critical role of sleep in promoting healthy development during adolescence, though more sleep than is recommended may confer little benefit for mental health. The findings demonstrate that mental health benefits may be obtainable at intervals as short as 15 min. • Mental health benefits differ based on sleep status. • Behaviors contribute differently to dimensions of mental health. • Beneficial outcomes of MVPA may be predicated on adolescents getting adequate sleep. • Replacing screen time with other behaviors is associated with better mental health. • Mental health benefits may be obtainable at intervals as short as 15 min. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: To examine the prevalence and associated factors of bidi and hookah use among Canadian youth. Methods: Data from 41,886 grade 7 to 12 youth were used to examine factors associated with bidi and hookah use. Results: Youth who are current or former cigarette smokers, have tried marijuana or alcohol, were more likely to use bidi or hookah. Conclusions: Results suggest bidi and hookah use may be an emerging issue in tobacco control among youth. Findings also support an integrated approach where future prevention efforts should address multiple risk behaviors. [Copyright &y& Elsevier]

Mental well-being can be conceptualized as two intersecting continua: mental illness (presence/absence of psychopathology) and mental health (flourishing/languishing). Together, mental illness and mental health combine to form an individual's complete mental health status (CMHS). The purpose of this study was to examine if CMHS is associated with adherence to the guidelines for moderate-to-vigorous physical activity (MVPA; 60 min), sleep (8–10 h) and recreational screen time (ST; ≤2 h) represented in the Canadian 24-h Movement Guidelines for Children and Youth ("Guidelines") in adolescents. This study reports cross-sectional student-level data from Year 6 (2017–18) of the COMPASS study. Canadian secondary school students (grades 9–12) completed questionnaires assessing their movement behaviours, flourishing/languishing (F/L), and high/low depressive symptoms (+DS/-DS). Students were classified into one of four CMHS groups: F/-DS, F/+DS, L/-DS, L/+DS. Generalized linear models were used to compare adherence to the guidelines between groups. A total of 29,133 students (49.8% female, M age = 15.3yrs) were included. For ST and sleep, youth classified as L/+DS were less likely to meet Guidelines than youth categorized as L/-DS, F/+DS, and F/-DS. For MVPA, youth categorized as L/+DS were less likely to meet Guidelines than youth categorized as F/-DS or F/+DS. Individuals classified as L/-DS were less likely to meet the MVPA guidelines compared to L/+DS (p s <.0001). This is the first study examining relationships between CMHS and Guideline adherence. CMHS was associated with both ST and sleep. Youth who self-report flourishing were more likely to achieve MVPA guidelines irrespective of depressive symptoms. Such findings reinforce the need for research considering both mental health and mental illness when examining associations with movement behaviours in youth. • First study examining youth complete mental health and movement behaviour adherence. • Flourishing, low depressive youth most likely to meet screen time and sleep guidelines. • Flourishing youth more likely to meet physical activity guideline. • Support for two-continua model of mental health and guideline adherence in youth. [ABSTRACT FROM AUTHOR]

Few multi-wave longitudinal studies have examined changes in drinking across extended periods of the coronavirus 2019 (COVID-19) pandemic. Using multiple indicators over three years, the current study examined: a) overall drinking changes; b) sex, income, age, and pre-COVID drinking level as moderators of changes; and c) the clinical significance of the observed changes. Using a longitudinal observational cohort design with nonclinical adults from the general community (N = 1395), assessments were collected over nine waves, two pre-COVID (April 2019 and October 2019) and seven intra-COVID (April 2020–April 2022). Drinking was measured as percent drinking days, percent heavy drinking days, and the Alcohol Use Disorders Identification Test (AUDIT) score. Clinically significant changes were defined based on the World Health Organization risk levels. All indicators exhibited significant changes from pre-pandemic to intra-pandemic periods, with drinking changes comprising early pandemic increases followed by subsequent decreases and AUDIT scores consistently declining. Pre-pandemic drinking level substantially moderated all changes. Heavier drinkers exhibited larger decreases compared to other drinking groups. In terms of clinically important changes, ∼10% of pre-pandemic abstinent or low-risk drinkers transitioned to medium- or high-risk status during the pandemic. In contrast, 37.1% of medium-risk drinkers and 44.6% of high-risk drinkers exhibited clinically significant decreases during the intra-pandemic period. Collectively, these findings highlight the multifarious impacts of the pandemic on drinking over time, comprising both increases and decreases in drinking behaviour. [ABSTRACT FROM AUTHOR]

Background Evaluating the interrelationship of health behaviors could assist in the development of effective public health interventions. Furthermore, the ability to identify cognitive mediators that may influence multiple behavioral changes requires evaluation. Purpose To evaluate covariation among health behaviors, specifically alcohol consumption, leisure-time physical activity, and smoking, and examine whether mastery acts as a mediating social-cognitive mechanism that facilitates multiple health behavior change in a longitudinal analysis. Methods In 2010, secondary data analysis was conducted on the first seven cycles of the Canadian National Population Health Survey. Data collection began in 1994-1995 and has continued biennially. At the time of this analysis, only seven cycles of data (2006-2007) were available. Parallel process growth curve models were used to analyze covariation between health behaviors and the potential mediating effects of perceived mastery. Results Increases in leisure-time physical activity were associated with reductions in tobacco use, whereas declines in alcohol consumption were associated with decreases in tobacco use. Covariation between alcohol consumption and leisure-time physical activity did not reach statistical significance. For the most part, mastery was unsuccessful in mediating the interrelationship of multiple behavioral changes. Conclusions Health behaviors are not independent but rather interrelated. In order to optimize limited prevention resources, these results suggest that population-level intervention efforts targeting multiple modifiable behavioral risk factors may not need to occur simultaneously. [ABSTRACT FROM AUTHOR]

Abstract: Background: Smoking susceptibility has been found to be a strong predictor of experimental smoking. This paper examined which student- and school-level factors differentiated susceptible never smokers from non-susceptible never smokers among a nationally representative sample of Canadian students in grades 9 to 12. Methods: Student-level data from the 2008–2009 Canadian Youth Smoking Survey were linked with school-level data from the 2006 Census, and one built environment characteristic (the density of tobacco retailers surrounding schools). These data were examined using multilevel logistic regression analyses. Results: The likelihood of a never smoker being susceptible to smoking significantly varied across schools (p= 0.0002). Students in this study were more likely to be susceptible never smokers if they reported low self-esteem, held positive attitudes towards smoking, used alcohol or marijuana, had close friends who smoked, and came from homes without a total ban on smoking. The school location (rural versus urban), the socioeconomic status of the neighbourhood surrounding a school, and the density of tobacco retailers that were located within 1-km radius of each school were not associated with students' smoking susceptibility. Conclusion: These findings underscore the continued need to develop school-based tobacco use prevention policies and/or programs that enhance students' self-esteem, address tobacco use misinformation and substance use, and include strategies targeting friends who smoke, and students who come from homes without a total ban on smoking. [Copyright &y& Elsevier]

Introduction: The negative effects of alcohol consumption on learning ability and intellectual development of youth may be recovered after cessation. This study explored to what extent reduction or complete cessation of alcohol consumption affects school performance of secondary school students.Methods: Alcohol use was self-reported by 37,223 grade 9-12 students attending 89 secondary schools across Ontario (n = 79) and Alberta (n = 10), Canada, participating in the COMPASS study over four years (school years 2013-14 to 2016-17). Measures included past-year frequency of drinking and frequency of binge drinking. A first-order autoregressive multinomial logistic regression was used to establish the impact of reduction or cessation of alcohol use on school performance.Results: During follow-up, 1465 (6.4%) reductions and 1903 (8.3%) cessations in alcohol consumption, and 1447 (10.1%) reductions and 2147 (14.9%) cessations of binge drinking were reported. Male students reported more cessation in both drinking (9.7% male vs 7.1% female) and binge drinking (15.6% male vs 14.4% female), though female students had higher rates of reductions. Students who quit or reduced their drinking or binge drinking were less likely to skip classes, leave their homework incomplete, or expect to get or to aspire to educational qualifications above a high school diploma compared to those who continued their alcohol use.Conclusions: Aside from health benefits, reduction or cessation of alcohol use may improve students' academic rigor. Prioritising school-based alcohol prevention efforts may therefore be beneficial for aspects of academic performance. [ABSTRACT FROM AUTHOR]

Introduction: Youth substance use prevention is a key public health priority. There is evidence that delaying substance use can improve health outcomes. While substance use is associated with negative outcomes at school, the benefits of delaying substance use on these outcomes are less well understood.Methods: The current study examined the substance use behaviours and school outcomes of 35,221 grade 12 students in Canada. Students were asked to report when they began using alcohol, cannabis, and tobacco products as well as school outcomes including school connectedness, math and English grades, truancy, and post-secondary aspirations and expectations. Regression models were used to examine the relationship between of age of initiation of alcohol, cannabis, and tobacco use and these outcomes.Results: Students who abstained from substance use throughout high school had higher school connectedness, lower truancy, and higher grades in grade 12 than students who did not. Earlier cannabis use was associated with increased truancy in grade 12. English grades were higher among students who did not use tobacco. Finally, post-secondary educational aspirations and expectations were higher among students who initiated substance use later.Conclusion: Grade 12 school outcomes were the best among students who abstained from substance use throughout high school. However, among students who did engage in substance use, school connectedness, truancy, English grades, and educational aspirations and expectations were more favourable among those who initiated substance use at a later age. [ABSTRACT FROM AUTHOR]

Background: To date, no longitudinal population-based studies of school start times have been conducted within Canada. School schedule changes provided an opportunity to examine start times in association with youth sleep, physical activity, and screen use over time.Methods: This longitudinal study included grade 9-12 students attending 49 Ontario secondary schools that participated in at least two consecutive years of the COMPASS study (2012-2017). Fixed effects models tested whether differences in within-student change in self-reported sleep duration, moderate-to-vigorous physical activity, and screen time were associated with school start time changes, adjusting for student- (grade, sex, ethnicity, spending money) and school-level covariates (median income, urbanicity, geographical area).Results: Thirteen start time changes of 5-10 min were reported. Ten-minute advances at earlier clock times (8:30 AM-8:20 AM; 8:40 AM-8:30 AM) were associated with steeper sleep duration declines than schools with consistent start times but had no effect at later times (9:00 AM-8:50 AM). While sleep change did not differ with 5-min delays, 10-min delays (8:50 AM-9:00 AM) were associated with additional sleep (23.7 min). Apart from one school that shifted from 8:30 AM to 8:35 AM, in which screen time and physical activity decreased more steeply, no effect was found for screen time, and 5-min delays were associated with more physical activity (10.9 min) and advances with less activity (-8.0 min).Conclusions: Results support start time delays as a valuable strategy to help ameliorate sleep debt among youth. Interference with physical activity or increased screen time appear unlikely with modest schedule changes. Potential adverse impacts on sleep require consideration with 10-min advances. [ABSTRACT FROM AUTHOR]

Abstract Introduction Harmful effects of cannabis use in youth scale with frequency. In the context of approaching legalization in Canada, understanding the distinctions between youth who change and who maintain their cannabis use is essential for designing interventions and policy. A substantial number of characteristics may play a role. This study assessed whether and how youth who change their cannabis use differ from those who do not. Methods Cannabis use was reported by 8375 Canadian high school students participating in the COMPASS study. GEE multiple logistic regressions were then used to establish impact of 13 baseline demographic and behavioural exposure variables on the likelihood of membership in four frequency change groups at follow-up a year later: reduction, cessation, escalation, and maintenance. Results Groups were found to differ in several ways. Cessation group members (19.4% of users) were less likely to binge drink (OR 0.82), vape (OR 0.82), or attend class without completing homework (OR 0.72) than maintainers. Students who reduced their use (14.6% of users) were more likely to binge drink (OR 1.36), smoke (OR 1.20), and skip class (OR 1.21). Those who escalated (29.5% of users) were more likely to be male (OR 1.35) and to vape (OR 1.22). Conclusions Students who change their cannabis use differ in several demographic and behavioural characteristics. The results raise further concerns about the impact of e-cigarettes and the role of poly-substance use in high-risk trajectories. Distinct classes of cannabis users, essential for policy and intervention development, can be identified in high school populations. Highlights • Four frequency change-based groups of cannabis users were shown to be distinct. • 36.5% maintained, 19.4% ceased, 14.6% reduced, and 29.5% escalated their use. • Groups were differentially associated with baseline characteristics. • Escalation was associated with male gender, e-cigarette vaping, and low Math marks. • Cessation was associated with academic rigor, cannabis-only use, and physical activity. [ABSTRACT FROM AUTHOR]