Has Cannabis Use Among Youth Increased After Changes in Its Legal Status? A Commentary on Use of Monitoring the Future for Analyses of Changes in State Cannabis Laws

Cannabis and children: risk mitigation strategies for edibles

In the era of (re)legalisation of medicinal and recreational cannabis, accidental and intentional exposure to edibles, cannabis-infused food products, has increased substantially. However, there is particular concern regarding younger age groups. Most concerning is the increase in hospitalisations. According to a study by Myran et al. (1), provinces in Canada, where the sale of edibles is permitted, saw an increase in paediatric poisonings due to unintentional consumption of edibles. Similar trends have been observed in "legalised states" in the US, such as Colorado (2). The impact of using cannabis at an early age, but particularly the impact of accidental exposure to high THC quantities, may have negative mental or physical health outcomes. Whilst regulatory restrictions vary significantly from one legalised region to another, it is difficult to identify a best practice. The aim of this study is to identify and discuss new and existing risk mitigation strategies to give guidance to policymakers. Furthermore, practical aspects, such as compliance (e.g. audits by authorities), are discussed. It is noted that edibles have been around much longer than recent political attempts to regulate them.

Health, safety, and socioeconomic impacts of cannabis liberalization laws: An evidence and gap map

Background

Globally, cannabis laws and regulations are rapidly changing. Countries are increasingly permitting access to cannabis under various decriminalization, medicalization, and legalization laws. With strong economic, public health, and social justice incentives driving these domestic cannabis policy reforms, liberalization trends are bound to continue. However, despite a large and growing body of interdisciplinary research addressing the policy-relevant health, safety, and socioeconomic consequences of cannabis liberalization, there is a lack of robust primary and systematic research that comprehensively investigates the consequences of these reforms.

Objectives

This evidence and gap map (EGM) summarizes the empirical evidence on cannabis liberalization policies. Primary objectives were to develop a conceptual framework linking cannabis liberalization policies to relevant outcomes, descriptively summarize the empirical evidence, and identify areas of evidence concentration and gaps.

Search Methods

We comprehensively searched for eligible English-language empirical studies published across 23 academic databases and 11 gray literature sources through August 2020. Additions to the pool of potentially eligible studies from supplemental sources were made through November 2020.

Selection Criteria

The conceptual framework for this EGM draws upon a legal epidemiological perspective highlighting the causal effects of law and policy on population-level outcomes. Eligible interventions include policies that create or expand access to a legal or decriminalized supply of cannabis: comprehensive medical cannabis laws (MCLs), limited medical cannabidiol laws (CBDLs), recreational cannabis laws (RCLs), industrial hemp laws (IHLs), and decriminalization of cultivations laws (DCLs). Eligible outcomes include intermediate responses (i.e., attitudes/behaviors and markets/environments) and longer-term consequences (health, safety, and socioeconomic outcomes) of these laws.

Data Collection and Analysis

Both dual screening and dual data extraction were performed with third person deconfliction. Primary studies were appraised using the Maryland Scientific Methods Scale and systematic reviews were assessed using AMSTAR 2.

Main Results

The EGM includes 447 studies, comprising 438 primary studies and nine systematic reviews. Most research derives from the United States, with little research from other countries. By far, most cannabis liberalization research focuses on the effects of MCLs and RCLs. Studies targeting other laws-including CBDLs, IHLs, and DCLs-are relatively rare. Of the 113 distinct outcomes we documented, cannabis use was the single most frequently investigated. More than half these outcomes were addressed by three or fewer studies, highlighting substantial evidence gaps in the literature. The systematic evidence base is relatively small, comprising just seven completed reviews on cannabis use (3), opioid-related harms (3), and alcohol-related outcomes (1). Moreover, we have limited confidence in the reviews, as five were appraised as minimal quality and two as low quality.

Authors’ Conclusions

More primary and systematic research is needed to better understand the effects of cannabis liberalization laws on longer-term-and arguably more salient-health, safety, and socioeconomic outcomes. Since most research concerns MCLs and RCLs, there is a critical need for research on the societal impacts of industrial hemp production, medical CBD products, and decriminalized cannabis cultivation. Future research should also prioritize understanding the heterogeneous effects of these laws given differences in specific provisions and implementation across jurisdictions.

Daily Cannabidiol Administration for 10 Weeks Modulates Hippocampal and Amygdalar Resting-State Functional Connectivity in Cannabis Users: A Functional Magnetic Resonance Imaging Open-Label Clinical Trial

Introduction: Cannabis use is associated with brain functional changes in regions implicated in prominent neuroscientific theories of addiction. Emerging evidence suggests that cannabidiol (CBD) is neuroprotective and may reverse structural brain changes associated with prolonged heavy cannabis use. In this study, we examine how an ∼10-week exposure of CBD in cannabis users affected resting-state functional connectivity in brain regions functionally altered by cannabis use. Materials and Methods: Eighteen people who use cannabis took part in a ∼10 weeks open-label pragmatic trial of self-administered daily 200 mg CBD in capsules. They were not required to change their cannabis exposure patterns. Participants were assessed at baseline and post-CBD exposure with structural magnetic resonance imaging (MRI) and a functional MRI resting-state task (eyes closed). Seed-based connectivity analyses were run to examine changes in the functional connectivity of a priori regions-the hippocampus and the amygdala. We explored if connectivity changes were associated with cannabinoid exposure (i.e., cumulative cannabis dosage over trial, and plasma CBD concentrations and Δ9-tetrahydrocannabinol (THC) plasma metabolites postexposure), and mental health (i.e., severity of anxiety, depression, and positive psychotic symptom scores), accounting for cigarette exposure in the past month, alcohol standard drinks in the past month and cumulative CBD dose during the trial. Results: Functional connectivity significantly decreased pre-to-post the CBD trial between the anterior hippocampus and precentral gyrus, with a strong effect size (d=1.73). Functional connectivity increased between the amygdala and the lingual gyrus pre-to-post the CBD trial, with a strong effect size (d=1.19). There were no correlations with cannabinoids or mental health symptom scores. Discussion: Prolonged CBD exposure may restore/reduce functional connectivity differences reported in cannabis users. These new findings warrant replication in a larger sample, using robust methodologies-double-blind and placebo-controlled-and in the most vulnerable people who use cannabis, including those with more severe forms of Cannabis Use Disorder and experiencing worse mental health outcomes (e.g., psychosis, depression).

Recreational Cannabis Legislation: substance use and impaired driving among Canadian rural and urban postsecondary students

BACKGROUND

Investigation of cannabis use trends among emerging adults (EA, aged between 18 and 24 years) following 2018 Canadian Recreational Cannabis Legislation (RCL) is critical. EAs report the heaviest cannabis use in Canada and are particularly vulnerable to the onset of problematic substance use.

OBJECTIVES

To describe and compare post-RCL use of cannabis and other state-altering substances, as well as the prevalence of impaired driving, among EA postsecondary students in both rural and urban settings, studying on one of five campuses in either Manitoba, Ontario, or Quebec.

METHODS

For this quantitative cross-sectional study, a self-report survey was administered to 1496 EA postsecondary students in the months following RCL (2018-2019). Multiple logistic regression analyses were conducted to explore the influence of provincial and urban/rural living contexts on recreational cannabis use, other state-altering substance use and impaired driving behaviours, adjusting for sociodemographic variables.

RESULTS

Statistically significant differences were observed between cohorts in almost all measures. Quebec students were more likely to have consumed cannabis during their lifetime (AOR = 1.41, 95% CI [1.05, 1.90]) than all other cohorts. Rural cohorts all had greater odds of reporting consumption of cannabis during the previous year compared to urban cohorts (AOR = 1.32, 95% CI [1.04, 1.67]). However, the relation between cannabis use in the last month and operating a motor vehicle after using cannabis (lifetime and past month) and living context differed between subjects in Quebec and those in the two other provinces. Quebec's students having lived mostly in urban contexts had greater odds of using cannabis in the past month and operating a motor vehicle after using cannabis (lifetime and past month) than those in rural contexts; the opposite was observed in Manitoba and Ontario. Differing interprovincial prohibitive/permissive legislation and licit cannabis infrastructure appeared to have little impact on post-RCL substance use.

CONCLUSIONS

In Manitoba and in Ontario, rural/urban living context seems to better predict substance use and related road-safety practices, suggesting these trends supersede permissive/prohibitive provincial legislation and licit cannabis-related infrastructures. Further investigation into sociodemographic factors influencing state-altering substance use and impaired driving, and maintaining tailored cannabis misuse prevention campaigns, is warranted on Canadian campuses.

Adolescent Cannabis Use During a Period of Rapid Policy Change: Evidence From the PATH Study

PURPOSE

To determine whether shifts in various state-level cannabis policies are associated with individual-level changes in adolescent cannabis use following implementation.

METHODS

We use the restricted-access youth cohort of the PATH Study, a recent, longitudinal, and nationally representative dataset, to assess whether changes in cannabis policy affect youth cannabis use. Data include respondents aged 12 to 17 years across up to six repeated observations (N = 26,673). Hybrid (between-person and within-person) panel models are used to examine adolescent past-month cannabis use.

RESULTS

Within-person effects showed that the odds of past-month cannabis use are lower (odds ratio [OR] = 0.632; p < .05) in years when a respondent's state allowed only cannabidiol (CBD) compared to years when the state had legalized medical cannabis. The odds of past-month cannabis use are lower during years when a respondent's state had decriminalized (OR = 0.617; p < .01) or criminalized (OR = 0.648; p < .05) adult recreational cannabis possession compared to years when it was legalized. These effects were robust to numerous controls, including time and state fixed effects. By contrast, significant between-person effects became nonsignificant with state fixed effects included, implying that state-level average use distinguishes average differences between states rather than policy.

DISCUSSION

Liberalized cannabis policy is significantly associated with recent adolescent cannabis use. The most consequential policy shift associated with adolescent use is from either criminalization or decriminalization of cannabis possession to legalization, such that states making these changes should consider additional prevention efforts.

The kids aren't alright: The effects of medical marijuana market size on adolescents

We exploit shocks to US federal enforcement policy to assess how legal medical marijuana market size affects youth marijuana use and consequences for youth traffic-related fatalities. Using hand-collected data on state medical marijuana patient rates to develop a novel measure of market size, we find that legal market growth increases youth marijuana use. Likely mechanisms are lower prices and easier access. Youth die more frequently from alcohol-involved car accidents, suggesting complementarities for youths. The consequences of marijuana legalization for youth are not immediate, but depend on how supply-side regulations affect production and prices.

Sex Differences in the Relationship Between Early Adverse Childhood Experiences, Delinquency, and Substance Use Initiation in High-Risk Adolescents

Adverse childhood experiences (ACEs) have been linked to a host of subsequent negative health and behavioral problems. However, the role of sex in the ramifications of early ACEs remains unclear, particularly for delinquency and substance use initiation in adolescence. A small body of research has produced mixed findings on sex differences in the relationship between ACEs and antisocial outcomes in adolescence, resulting in uncertainty about whether and how ACEs may operate differently for boys and girls. The current study drew on a high-risk group of adolescents (N=2455; M_age=15.4; 48% female; 50% Black, 23% Hispanic) from the Fragile Families and Child Wellbeing Study to examine the associations between accumulated ACEs across early childhood, and delinquency and substance use initiation of alcohol, cigarette, and cannabis in adolescence. We utilized mother and father reports on the exposure to seven different types of ACEs (i.e., physical abuse, psychological abuse, neglect, parental substance misuse, parental mental illness, parental intimate partner violence, and parental criminal behavior) when adolescents were ages 1, 3, and 5. Total ACEs scores and their relationships with delinquency, and lifetime use of alcohol, cigarettes, and cannabis were assessed separately for girls and boys. Results suggested that accumulated ACEs during early childhood may be implicated in boys' delinquency, while ACEs were not significantly associated with girls' self-reported delinquency or for boys' and girls' substance use initiation. Findings suggest that the enduring consequences of ACEs may be sex-specific, and have implications for the development of policies to mitigate ACEs and their harms.

Association of Recreational Cannabis Legalization With Cannabis Possession Arrest Rates in the US

Importance

Recreational cannabis legalization (RCL) has been advocated as a way to reduce the number of individuals interacting with the US criminal justice system; in theory, however, cannabis decriminalization can achieve this objective without generating the negative public health consequences associated with RCL. It is still unclear whether RCL can bring additional benefits in terms of reducing cannabis possession arrests in states that have already decriminalized cannabis.

Objective

To examine whether RCL was associated with changes in cannabis possession arrests in US states that had already decriminalized cannabis during the study period and whether these changes differed across age and racial subgroups.

Design, Setting, and Participants

This repeated cross-sectional study used cannabis possession arrest data from the Federal Bureau of Investigation Uniform Crime Reporting Program (UCRP) for US states from 2010 through 2019. Statistical analysis was conducted from October 6, 2021, to October 12, 2022.

Exposures

Implementation of statewide RCL.

Main Outcomes and Measures

Cannabis possession arrest rates per 1000 population per year were assessed with a quasi-experimental difference-in-differences design and were used to estimate the association of RCL with arrest rates in RCL states that had or had not decriminalized cannabis before RCL. This association was also examined in subgroups for age (adults vs youths) and race (Black vs White).

Results

This study included UCRP data for 31 US states, including 9 states that implemented RCL during the study period (4 without and 5 with decriminalization) and 22 non-RCL states. In the 4 states that had not decriminalized cannabis before legalization, RCL was associated with a 76.3% decrease (95% CI, -81.2% to -69.9%) in arrest rates among adults. In the 5 states that had already decriminalized cannabis, RCL was still associated with a substantial decrease in adult arrest rates (-40.0%; 95% CI, -55.1% to -19.8%). There was no association of RCL with changes in arrest rates among youths. In addition, changes in arrest rates associated with RCL did not differ among Black and White individuals.

Conclusions and Relevance

In this repeated cross-sectional study, RCL was associated with a sizable reduction in cannabis possession arrests among adults in states that had already decriminalized cannabis during the study period (2010-2019), albeit the magnitude was smaller compared with states that had not decriminalized cannabis before RCL. In addition, RCL did not seem to be associated with changes in arrest rates among youths or disparities in arrest rates among Black and White individuals.

Crime in a Time of Cannabis: Estimating the Effect of Legalizing Marijuana on Crime Rates in Colorado and Washington Using the Synthetic Control Method

The legalization of marijuana for recreational use continues to expand across America. Colorado and Washington were the first states to legalize marijuana in 2012. A primary concern regarding legalization is how these policy changes affect crime rates. Researchers have begun to estimate the effect marijuana legalization has had on crime rates. We extend this literature by using a different analytical approach. State level data covering years 2000–2019 were analyzed using the synthetic control method to find that legalizing marijuana for recreational use in Colorado and Washington was generally not associated with variations in index crime rates. These findings substantiate prior research. Increased crime rates should not be a primary concern as more states move to adopt recreational marijuana use legislation. Instead, the benefits to states via harm reduction, increased tax revenue, and a more efficient allocation of policing resources ought to be more of a consideration for states when passing recreational marijuana legislation.

Prevalence and use of cannabis products and routes of administration among youth and young adults in Canada and the United States: A systematic review

BACKGROUND

The current systematic review aimed to summarize the literature on the prevalence of routes of administration and cannabis products used among youth and young adults in Canada and the United States (US).

METHODS

Five academic databases were searched in April 2020 and February 2021. Peer-reviewed articles were included if they were a population-based quantitative observational study describing the prevalence of a cannabis product or route of administration among youth and young adults in Canada or the US. Risk of bias was assessed using Hoy and colleagues' risk of bias assessment tool. A narrative review was conducted.

RESULTS

Twenty-six studies were identified for the following routes of administration: smoking (n = 16), vaping (n = 21), dabbing (n = 3), oral (n = 13), topical (n = 1); and products: dried flower (n = 2), and concentrates (n = 8). Smoking had the highest prevalence rates among youth and young adults; however, rates of use appeared to reduce over time. Conversely, prevalence of vaping appeared to increase over time. Fewer studies focused on oral or dabbed cannabis but those that did reported prevalence estimates of approximately a third among recent cannabis consumers.

DISCUSSION

The heterogeneity of cannabis routes of administration restricted our ability to collate average prevalence estimates. In jurisdictions where non-medical cannabis is legal, policymakers should provide guidance and education to youth on each type of product and routes of administration.

OTHER

Funding for this study was provided by a Canadian Institutes of Health Research (PJT-153342). The current review was registered with PROSPERO (CRD42020169275).

Relationships of Cannabis Policy Liberalization With Alcohol Use and Co-Use With Cannabis: A Narrative Review

PURPOSE

The liberalization of cannabis policies has the potential to affect the use of other substances and the harms from using them, particularly alcohol. Although a previous review of this literature found conflicting results regarding the relationship between cannabis policy and alcohol-related outcomes, cannabis policies have continued to evolve rapidly in the years since that review.

SEARCH METHODS

The authors conducted a narrative review of studies published between January 1, 2015, and December 31, 2020, that assessed the effects of cannabis policies on the use of alcohol in the United States or Canada.

SEARCH RESULTS

The initial search identified 3,446 unique monographs. Of these, 23 met all inclusion criteria and were included in the review, and five captured simultaneous or concurrent use of alcohol and cannabis.

DISCUSSION AND CONCLUSIONS

Associations between cannabis policy liberalization and alcohol use, alcohol-related outcomes, and the co-use of alcohol and cannabis were inconclusive, with studies finding positive associations, no associations, and negative associations. Although several studies found that cannabis policy liberalization was associated with decreases in alcohol use measures, these same studies showed no impact of the cannabis policy on cannabis use itself. The lack of a consistent association was robust to subject age, outcome measure (e.g., use, medical utilization, driving), and type of cannabis policy; however, this may be due to the small number of studies for each type of outcome. This paper discusses several notable limitations of the evidence base and offers suggestions for improving consistency and comparability of research going forward, including a stronger classification of cannabis policy, inclusion of measures of the alcohol policy environment, verification of the impact of cannabis policy on cannabis use, and consideration of mediation effects.

Cannabis decriminalization and racial disparity in arrests for cannabis possession

RATIONALE

Minorities often bear the brunt of unequal enforcement of drug laws. In the U.S., Blacks have been disproportionately more likely to be arrested for cannabis possession than Whites despite a similar rate of cannabis use. Decriminalizing cannabis has been argued as a way to reduce racial disparity in cannabis possession arrests. To date, however, the empirical evidence to support this argument is almost non-existent.

OBJECTIVES

To examine whether cannabis decriminalization was associated with reduced racial disparity in arrests for cannabis possession between Blacks and Whites in the U.S.

METHODS

Using FBI Uniform Crime Report data from 37 U.S. states, cannabis possession arrest rates were calculated separately for Blacks and Whites from 2000 to 2019. A difference-in-differences framework was used to estimate the association between cannabis decriminalization and racial disparity in cannabis possession arrest rates (Blacks/Whites ratio) among adults and youths.

RESULTS

Cannabis possession arrest rates declined over 70% among adults and over 40% among youths after the implementation of cannabis decriminalization in 11 states. Among adults, decriminalization was associated with a roughly 17% decrease in racial disparity in arrest rates between Blacks and Whites. Among youths, arrest rates declined among both Blacks and Whites but there was no evidence for a change in racial disparity between Blacks and Whites following decriminalization.

CONCLUSIONS

Cannabis decriminalization was associated with substantially lower cannabis possession arrest rates among both adults and youths and among both Blacks and Whites. It reduced racial disparity between Blacks and Whites among adults but not youths. These findings suggested that cannabis decriminalization had its intended consequence of reducing arrests and may have potential to reduce racial disparity in arrests at least among adults.

Heroin use cannot be measured adequately with a general population survey

BACKGROUND

Globally, heroin and other opioids account for more than half of deaths and years-of-life-lost due to drug use and comprise one of the four major markets for illegal drugs. Having sound estimates of the number of problematic heroin users is fundamental to formulating sound health and criminal justice policies. Researchers and policymakers rely heavily upon general population surveys (GPS), such as the US National Survey on Drug Use and Health (NSDUH), to estimate heroin use, without confronting their limitations. GPS-based estimates are also ubiquitous for cocaine and methamphetamine, so insights pertaining to GPS for estimating heroin use are also relevant for those drug markets.

ANALYSIS

Four sources of potential errors in NSDUH are assessed: selective non-response, small sample size, sampling frame omissions and under-reporting. An alternative estimate drawing on a variety of sources including a survey of adult male arrestees is presented and explained. Other approaches to prevalence estimation are discussed.

FINDINGS

Under-reporting and selective non-response in NSDUH are likely to lead to substantial underestimation. Small sample size leads to imprecise estimates and erratic year-to-year fluctuations. The alternative estimate provides credible evidence that NSDUH underestimates the number of frequent heroin users by at least three-quarters and perhaps much more.

IMPLICATIONS

GPS, even those as strong as NSDUH, are doomed by their nature to estimate poorly a rare and stigmatized behavior concentrated in a hard-to-track population. Although many European nations avoid reliance upon these surveys, many others follow the US model. Better estimation requires models that draw upon a variety of data sources, including GPS, to provide credible estimates. Recent methodological developments in selected countries can provide guidance. Journals should require researchers to critically assess the soundness of GPS estimates for any stigmatized drug-related behaviors with low prevalence rates.

The Intersection Between Sex and Race in Understanding Substance Co-Use Patterns in Adolescents From the Fragile Families Study

The current study examined the prevalence of alcohol, cigarette, and cannabis co-use among a longitudinal cohort of youth predominately born to single-parent families. Data were drawn from wave six of the Fragile Families and Child Wellbeing Study ( N = 2976; M age = 15.6; 49% female; 53% non-Hispanic Black, 27% Hispanic, 20% White). Adolescents’ reports of their past 30-day use of alcohol, cigarettes, and cannabis were used to construct eight mutually exclusive use groups. Multinomial logistic regressions adjusting for sociodemographic factors revealed that Black adolescents were at lower relative risk of using Alcohol Only compared to White adolescents. Black males were at greater relative risk of using Cannabis Only than both White males and Black females. Finally, Hispanic males were at a marginally increased relative risk of co-using Alcohol and Cannabis compared to White males. Prevention efforts targeting Black and Hispanic males’ use of cannabis (both alone and in combination with alcohol) may be beneficial.

Trends in youth cannabis use across cannabis legalization: Data from the COMPASS prospective cohort study

Canada legalized recreational cannabis use for adults on October 17, 2018 with decision-makers emphasising the need to reduce cannabis use among youth. We sought to characterise trends of youth cannabis use before and after cannabis legalization by relying on a quasi-experimental design evaluating cannabis use among high school students in Alberta, British Columbia, Ontario, and Québec who participated in the COMPASS prospective cohort study. Overall trends in use were examined using a large repeat cross-sectional sample (n = 102,685) at two time points before legalization (16/17 and 17/18 school years) and one after (18/19 school year). Further differential changes in use among students affected by legalization were examined using three sequential four-year longitudinal cohorts (n = 5,400) of students as they progressed through high school. Youth cannabis use remains common with ever-use increasing from 30.5% in 2016/17 to 32.4% in 2018/19. In the repeat cross-sectional sample, the odds of ever use in the year following legalization were 1.05 times those of the preceding year (p = 0.0090). In the longitudinal sample, no significant differences in trends of cannabis use over time were found between cohorts for any of the three use frequency metrics. Therefore, it appears that cannabis legalization has not yet been followed by pronounced changes on youth cannabis use. High prevalence of youth cannabis use in this sample remains a concern. These data suggest that the Cannabis Act has not yet led to the reduction in youth cannabis use envisioned in its public health approach.

Examining Sex and Racial/Ethnic Differences in Co-use of Alcohol, Cannabis, and Cigarettes in a Community Sample of Adolescents

INTRODUCTION

Although adolescents often co-use alcohol, cigarettes, and cannabis, little is known about sex and racial/ethnic differences in the co-use of these substances. Therefore, this investigation examined sex and racial/ethnic differences in alcohol, cigarette, and cannabis co-use in a large and ethnically diverse group. Methods: Participants were drawn from a large, multi-site study of adolescents from three regions in the United States (N = 4,129; Mage=16.10 years, SD = 0.59; 51% female, 49% male; 37% Black, 37% Hispanic, 25% White). Participants were categorized into eight mutually exclusive groups based on their self-reported use of alcohol, cannabis, and cigarettes in the last 30 days. Results: Unadjusted multinomial logistic regression revealed that males were more likely than females to use cannabis-only and to co-use all three substances. Additionally, Black and Hispanic adolescents were more likely to use cannabis-only, while White adolescents were more likely than Black and Hispanic adolescents to co-use alcohol and cigarettes. After adjusting for other sociodemographic variables (age, household income, parental education, and parent marital status), males were more likely to use cannabis-only than females; White youth were more likely than Hispanic youth to use cigarettes only and co-use cigarettes and alcohol. White youth were more likely than Black youth to co-use alcohol and cigarettes and co-use all three substances. Discussion: These results indicate sex and racial/ethnic differences in substance co-use that were not explained by socioeconomic factors. Results of this work suggest potential strategies for targeted prevention efforts and underscore the importance of continued efforts to better understand patterns of alcohol and substance co-use.

Cannabis-related driving and passenger behaviours among high school students: a cross-sectional study using survey data

BACKGROUND

Many youth report driving under the influence of cannabis (DUIC) and riding with a cannabis-impaired driver (RWCD), and many perceive that cannabis causes limited impairment. We examined associations of perceived risk of regular cannabis use with DUIC and RWCD, exploring differences by sex and rural setting.

METHODS

In a cross-sectional study, we examined DUIC and RWCD among high school students in grades 11 and 12 who participated in the 2016-2017 Canadian Student Tobacco, Alcohol and Drugs Survey. Private and public schools across 9 Canadian provinces were included. New Brunswick and the 3 territories were not included. Multinomial logistic regression models generated adjusted and unadjusted models for the associations.

RESULTS

A total of 52 103 students in grades 7-12, from 117 school boards and 699 schools, participated in the survey. The survey response rate was 76.2% (n = 52 103/68 415). In total, 14 520 students in grades 11 and 12 participated in the survey. Greater perceived risk of regular cannabis use was associated with reduced risk of DUIC and RWCD in a dose-response manner. Students perceiving that regular cannabis use posed great risk had an adjusted relative risk (RR) of 0.06 (95% confidence interval [CI] 0.04-0.10) of DUIC in the past 30 days compared with students perceiving that regular use posed no risk. Students perceiving that regular cannabis use posed great risk had an adjusted RR of 0.09 (95% CI 0.07-0.12) of RWCD in the past 30 days compared with students perceiving no such risk. Associations were consistent for male and female students and for those living in urban and rural areas.

INTERPRETATION

Students perceiving minimal risk from cannabis use reported greater engagement in cannabis-related risky driving behaviours. Given the importance of youth perceptions in shaping driving and passenger behaviours, efforts must be made to disseminate appropriate information regarding cannabis-related driving risks to high school students.