Cannabis use among Canadian adolescents has decreased since the country legalised the drug in 2018, according to the results of a federally funded study.
Using Canada’s annual COMPASS Study, researchers from the University of Waterloo and Brock University analysed data from more than 65,000 students across 85 secondary schools, comparing usage patterns before legalisation (2017-2018) and four years after (2021-2022).
The study, published in the journal Addictive Behaviors Reports, found that 15 per cent of students reported past-month cannabis use before legalisation, compared to 12.3 per cent in the post-legalisation cohort. The research also noted increased reports of students who said they had never used cannabis.
The findings add to a growing body of evidence suggesting that legalisation has not led to increased youth consumption, despite warnings from opponents that it would make cannabis more accessible to young people.
Beyond measuring usage rates, the researchers identified significant changes in the risk factors associated with cannabis use between the two periods.
Before legalisation, the top predictors were time spent texting or messaging, daily breakfast consumption, and time spent doing homework. After legalisation, depression, home life quality, and students’ attitudes towards academic achievement became more prominent indicators.
“Our results highlight an increase in reports of cannabis never use and a slight decline in current cannabis use in our samples,” the study authors wrote. “The risk factor profile for cannabis use has substantively changed, increasingly implicating elevations in internalising mental health conditions.”
The researchers identified the highest-risk group post-legalisation as students who did not eat breakfast daily, placed a lower value on good grades, and showed elevated anxiety scores. This group comprised 18.8 per cent of the sample and had a 27 per cent probability of current cannabis use.
The Canadian research aligns with similar studies from other jurisdictions that have legalised cannabis.
A German government report released earlier this year found that youth use had not increased following that country’s nationwide legalisation. Federal health data from Germany showed rates of cannabis use among young people actually declined after legalisation took effect.
In the United States, research showed that youth cannabis use declined in 19 out of 21 states that legalised adult-use cannabis, with teen consumption down an average of 35 per cent in the earliest states to legalise.
The annual Monitoring the Future Survey, supported by the National Institute on Drug Abuse, found that cannabis use among eighth, tenth and twelfth graders in the US is now lower than before the first states began enacting legalisation laws in 2012.
Despite the overall decline in youth cannabis use, the Canadian researchers emphasised that prevention programmes need to evolve to address changing risk factors.
“Given that cannabis use among youth remains common, there is a pressing need to identify the characteristics of youth who are at the greatest risk for cannabis misuse and, in turn, to develop and deploy early prevention and intervention programmes tailored to these needs in high-risk youth,” the study stated.
The research was funded by the Canadian Institutes of Health Research and Quebec’s Ministry of Health and Social Services, using data from the ongoing COMPASS Study, which tracks health behaviours among Canadian secondary school students.
The findings suggest that whilst cannabis legalisation has not led to increased youth consumption, continued education remain necessary to address problematic use patterns among vulnerable groups.
