Cannabis use frequency increased following legalization with a decrease in misuse observed

1. In this prospective cohort study, cannabis use frequency increased significantly while misuse decreased.  

Evidence Rating Level: 1 (Excellent)

Globally, increasing numbers of jurisdictions are legalizing or plan to legalize the use of recreational cannabis. Canada legalized cannabis in 2018, becoming the first country in the Group of Seven to do so. Before legalization, there were concerns that cannabis use and misuse would increase. Since legalization, there is some evidence that supports this however, other studies have found conflicting results. To address this gap, this study sought to examine the changes in cannabis use and misuse in a cohort of adults since legalization in Canada. Additionally, determining if the frequency of cannabis use before legalization altered the trajectory of use post-legalization. Participants between the ages of 18 to 65 were recruited from St. Joseph’s Healthcare Hamilton in Ontario, Canada. Participants were eligible to participate if they had a minimum ninth-grade education and no terminal illness. The primary outcomes of the study were cannabis use frequency and misuse. To measure cannabis use frequency, participants answered questions from the Canadian Cannabis Survey. To measure cannabis misuse, the 8-item Cannabis Use Disorder Identification Test – Revised (CUDIT-R) scale. A total of 1428 adults were included (mean [SD] age, 34.5 [13.9] years). There was a significant increase in cannabis use frequency (β=0.35; 95% CI, 0.19 to 0.51), to the point that the proportion of days using cannabis increased by 0.35% per year. However, the CUDIT-R scores found a significant decrease in cannabis use frequency overall (β=-0.08 [95% CI, -0.10 to -0.06] per year; P<.001). There was a significant decrease in cannabis use among individuals who were weekly cannabis users at baseline, while there was a slight increase in those who were using cannabis monthly or less. In terms of cannabis product preferences, there were significant decreases in the use of solid and liquid concentrates, cannabis oil, among others, and an increase in the use of edibles, liquids, and disposable vape pens. In summary, this prospective cohort study found an increase in cannabis use and a decrease in misuse. 

Click to read the study in JAMA Network Open

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