Cannabis use after Canadian legalization increased mainly among people without mental health problems

Past 12-month cannabis use increased from pre-legalization among those with anxiety (AOR 1.33) in the year immediately following legalization. Daily and 12-month use increased among Canadians not reporting mental health problems. No other pre-post legalization differences were observed among individuals with bipolar disorder, PTSD, or schizophrenia.

Data from the International Cannabis Policy Study's annual repeat cross-sectional surveys in Canada from 2018 to 2023 (one year pre- to five years post-legalization). Analysis included 92,843 Canadians aged 16-65. Adjusted logistic regression examined changes in daily and past 12-month use by mental health status.

A major concern about legalization is that vulnerable populations, particularly those with mental health conditions, would increase cannabis use. This large-scale Canadian study provides reassuring evidence that the increase in use was driven primarily by people without mental health problems.

This finding from the Lancet Regional Health suggests that legalization did not disproportionately increase cannabis use among the most vulnerable Canadians. The temporary increase among people with anxiety in the first year after legalization may reflect a specific subgroup exploring cannabis for symptom management, though this effect did not persist.

Repeat cross-sectional design means different people were surveyed each year. Self-reported mental health conditions may not match clinical diagnoses. Cannabis use is also self-reported. The study cannot capture changes within individuals over time. Legalization effects may take longer than five years to fully manifest.