Science & Health
Youth Marijuana Use Has Declined Since Canada Enacted Legalization, Federally Funded Study Shows
A federally funded study out of Canada shows that youth marijuana use rates have declined after the country legalized cannabis—contradicting concerns voiced by prohibitionists.
Using data from Canada’s annual COMPASS Study, researchers at the University of Waterloo and Brock University compared marijuana use trends among adolescents from 2017-2018 (pre-legalization) and 2021-2022 (post-legalization).
The study—published in the journal Addictive Behaviors Reports—found that 15 percent of students in the pre-legalization cohort reported past-month cannabis use, while 12.3 percent in the post-legalization group reported the same. Also, there was “increased” accounts of students who said they never use marijuana in the latter demographic.
Beyond analyzing cannabis usage rates, the researchers also sought to identify “risk factors” that could predict whether a student is likely to use marijuana. And those factors did change between the two pre- and post-legalization groups, which “suggests that prevention efforts need to adapt over time to target the relevant risk factors associated with cannabis use.”
Specifically, the study of more than 65,000 students over the two time periods found that, although many risk factors “were common across years,” the “relative ranking of risk factors changed considerably.”
“The top predictors of current cannabis use [pre-legalization] were time spent texting/messaging, daily breakfast consumption, and time spent doing homework; all of which also remained as important predictors in 2021–22,” the study authors said. “The top predictors of current cannabis use [post-legalization] were depression, happy home life…and students believing that getting good grades was important.”
“Our results highlight an increase in reports of cannabis never use and a slight decline in current cannabis use in our samples,” the study says. “While this is contrary to evidence of a plateau in cannabis use among youth during the early stages of the COVID-19 pandemic, it may indicate that the declines observed here (a few years out from the pandemic-related restrictions) may not be a result of the pandemic but more likely due to regulations association with legalization and/or changes in social norms.”
“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 programs tailored to these needs in high-risk youth. This study provides evidence that, in a relatively short 4-year period spanning the cannabis pre-legalization to post-legalization time periods, adolescent cannabis use has declined, but the risk factor profile for cannabis use has substantively changed, increasingly implicating elevations in internalizing mental health conditions. Locally relevant and timely ongoing surveillance efforts are required to inform cannabis control efforts moving forward.”
The COMPASS Study is funded by the Canadian Institutes of Health Research as well as the province of Quebec’s Ministry of Health and Social Services.
The study was released about three months after German officials released a separate report on their country’s experience with legalizing marijuana nationwide.
That report found that fears from opponents about youth use—as well as traffic safety and other concerns—have so far proved largely unfounded.
A separate recent study conducted by German federal health officials also found that rates of marijuana use declined among youth after the country legalized adult-use cannabis, contradicting one of the more common prohibitionist arguments against the reform.
Back in July, federal health data also indicated that while past-year marijuana use in the U.S. overall has climbed in recent years, the rise has been “driven by increases…among adults 26 years or older.” As for younger Americans, rates of both past-year use and cannabis use disorder, by contrast, “remained stable among adolescents and young adults between 2021 and 2024.”
Across the U.S., research suggests that marijuana use by young people has generally fallen in states that legalize the drug for adults.
A report from the advocacy group Marijuana Policy Project (MPP), for example, found that youth marijuana use declined in 19 out of 21 states that legalized adult-use marijuana—with teen cannabis consumption down an average of 35 percent in the earliest states to legalize.
The report cited data from a series of national and state-level youth surveys, including the annual Monitoring the Future (MTF) Survey, which is supported by the National Institute on Drug Abuse (NIDA).
The latest version of the MTF, released late last year, found that cannabis use among eighth, 10th and 12 graders is now lower than before the first states started enacting adult-use legalization laws in 2012. There was also a significant drop in perceptions by youth that cannabis is easy to access in 2024 despite the widening adult-use marketplace.
Another survey from the U.S. Centers for Disease Control and Prevention (CDC) last year also showed a decline in the proportion of high-school students reporting past-month marijuana use over the past decade, as dozens of states moved to legalize cannabis.
At the state level, MPP’s assessment looked at research such as the Washington State Healthy Youth Survey that was released in April 2024.
That survey showed declines in both lifetime and past-30-day marijuana use in recent years, with striking drops that held steady through 2023. The results also indicated that perceived ease of access to cannabis among underage students has generally fallen since the state enacted legalization for adults in 2012—contrary to fears repeatedly expressed by opponents of the policy change.
In June of last year, meanwhile, the biannual Healthy Kids Colorado Survey found that rates of youth marijuana use in the state declined slightly in 2023—remaining significantly lower than before the state became one of the first in the U.S. to legalize cannabis for adults in 2012.
The findings broadly track with other past surveys that have investigated the relationship between jurisdictions that have legalized marijuana and youth cannabis use.
For example, a Canadian government report recently found that daily or near-daily use rates by both adults and youth have held steady over the last six years after the country enacted legalization.
Another U.S. study reported a “significant decrease” in youth marijuana use from 2011 to 2021—a period in which more than a dozen states legalized marijuana for adults—detailing lower rates of both lifetime and past-month use by high-school students nationwide.
Another federal report published last summer concluded that cannabis consumption among minors—defined as people 12 to 20 years of age—fell slightly between 2022 and 2023.
Separately, a research letter published by the Journal of the American Medical Association (JAMA) in April 2024 said there’s no evidence that states’ adoption of laws to legalize and regulate marijuana for adults have led to an increase in youth use of cannabis.
Another JAMA-published study earlier that month that similarly found that neither legalization nor the opening of retail stores led to increases in youth cannabis use.
In 2023, meanwhile, a U.S. health official said that teen marijuana use has not increased “even as state legalization has proliferated across the country.”
Another earlier analysis from the U.S. Centers for Disease Control and Prevention found that rates of current and lifetime cannabis use among high school students have continued to drop amid the legalization movement.
A separate NIDA-funded study published in the American Journal of Preventive Medicine in 2022 also found that state-level cannabis legalization was not associated with increased youth use. The study demonstrated that “youth who spent more of their adolescence under legalization were no more or less likely to have used cannabis at age 15 years than adolescents who spent little or no time under legalization.”
Yet another 2022 study from Michigan State University researchers, published in the journal PLOS One, found that “cannabis retail sales might be followed by the increased occurrence of cannabis onsets for older adults” in legal states, “but not for underage persons who cannot buy cannabis products in a retail outlet.”
The trends were observed despite adult use of marijuana and certain psychedelics reaching “historic highs” in 2022, according to separate 2023 data.
Photo courtesy of Chris Wallis // Side Pocket Images.
