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May 14, 2025 – Toronto, Canada
Five years after Canada legalized recreational cannabis, a new study published in JAMA Network Open reveals that cannabis use among adults has changed only modestly, with a slight increase in frequency and a decrease in cannabis misuse.
Researchers from McMaster University followed 1,428 adults over five years, measuring both the frequency of cannabis use and the prevalence of cannabis misuse. The findings indicate that the average proportion of days using cannabis rose by just 1.75% over five years, while indicators of cannabis misuse, as measured by the Cannabis Use Disorder Identification Test–Revised (CUDIT-R), fell by 0.4 points over the same period.
Dr. André J. McDonald, lead author and postdoctoral fellow at McMaster, told Medscape Medical News, “It is important to note that both effect sizes were quite small, so we are looking at modest changes. Still, our finding that cannabis use frequency increased is concerning from a public health perspective.”
Key Findings
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Minimal Increase in Use: Cannabis use frequency increased by just 0.35% annually.
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Decrease in Misuse: Cannabis misuse scores dropped both annually and over the five-year period.
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Prelegalization Patterns Matter: Those who used cannabis frequently before legalization actually showed decreases in both use and misuse after legalization.
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Youth Trends: The decline in misuse was most pronounced among participants under 30, aligning with typical patterns where substance misuse peaks in early adulthood and then declines.
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Product Preferences Shifted: There was a notable move away from dried flower (down from 81.3% to 64.6% among active users) and an increase in the use of edibles and vape cartridges (up from 18.4% to 33.0%).
Dr. McDonald highlighted that the shift from combustible products to alternatives like edibles and vape pens could be viewed positively, though he cautioned that some vape products contain high levels of THC.
Expert Commentary
Dr. Sameer Imtiaz of the University of Toronto, who was not involved in the study, praised the research for its robust design and long-term follow-up. He noted that the study’s approach-tracking the same individuals before and after legalization-offers a more nuanced picture than previous cross-sectional studies.
However, Dr. Imtiaz also pointed out that the study’s findings may not be fully generalizable, as the sample was predominantly female (60%), highly educated (92% with postsecondary education), and unmarried (68%).
Implications
The study suggests that fears of a dramatic rise in cannabis use and misuse following legalization may have been overstated. Instead, legalization appears to have had a modest impact, with some positive trends, particularly among younger adults and previous frequent users.
Disclaimer:
This article is based on findings reported by Medscape Medical News and the study published in JAMA Network Open. The information provided is for general informational purposes only and should not be construed as medical advice. For personal health concerns or decisions about cannabis use, please consult a qualified healthcare professional.
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