Five Years After Canadian Legalization, Cannabis Use Rose Modestly but Misuse Actually Decreased

Cannabis use frequency increased by 0.35% of days per year overall (1.75% over 5 years). CUDIT-R misuse scores decreased by 0.08 points per year (0.4 over 5 years). Critically, pre-legalization frequent consumers showed the largest decreases in both use and misuse, while occasional users and nonusers showed modest increases. Product preferences shifted from dried flower toward edibles, liquids, and vape pens.

Prospective cohort study with up to 11 biannual assessments from September 2018 to October 2023 in Ontario, Canada. 1,428 community-dwelling adults aged 18-65. Mean 90% retention across all waves. Linear mixed-effects modeling assessed changes in cannabis use frequency and CUDIT-R scores.

This is among the first longitudinal studies to track the same individuals through cannabis legalization. The finding that misuse decreased even as use increased, and that frequent users improved the most, provides the most nuanced picture yet of legalization's within-person effects.

The decrease in misuse among frequent users may reflect the normalization and regulation of cannabis removing some of the risk-taking behavior associated with illegal use. The product diversification (from flower to edibles) aligns with a market maturation that could have both positive (less smoking) and negative (delayed onset risks) public health implications.

Ontario-specific population. Self-reported use and misuse. The COVID-19 pandemic overlapped with the study period, confounding interpretation. Attrition could bias results if those worsening dropped out.