Across nearly 93,000 Canadians surveyed over five years, cannabis use increased mainly among those without mental health conditions, while people with anxiety, depression, bipolar disorder, PTSD, or schizophrenia showed few changes in use after legalization.
Policymakers evaluating legalization impacts on vulnerable populations, and mental health professionals.
Cannabis use post-legalization increased among Canadians without mental health problems, not among those with conditions
What the researchers found
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.
Why it matters
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.
The numbers in context
92,843 Canadians across 6 annual surveys (2018-2023). Cannabis use increase among those with anxiety: AOR 1.33 (95% CI 1.15-1.53) in 2019 only. Increases in daily and 12-month use observed among those without mental health problems. No significant changes for bipolar, PTSD, or schizophrenia.
How the study worked
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.
What this study cannot tell us
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.
How to read the evidence
Large-scale (n=92,843) national repeat cross-sectional study published in Lancet Regional Health, though limited by cross-sectional design.
When this study was published
Published in 2026, covering 2018-2023.
The bigger picture
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.
Questions still open
- Why did the anxiety-related increase in use not persist beyond the first year? Are people with mental health conditions self-regulating their cannabis use? Would clinical populations (rather than self-reported) show different patterns?
Common questions
Did legalization increase cannabis use among people with mental health conditions?
Who did increase their cannabis use after legalization?
Read the original research
The prevalence of cannabis use pre-versus post-cannabis legalization in Canada by mental health status: findings from national repeat cross-sectional surveys.
Lancet regional health. Americas, 55, 101373
Citation
Rundle, Samantha; Iraniparast, Maryam; Hammond, David. (2026). The prevalence of cannabis use pre-versus post-cannabis legalization in Canada by mental health status: findings from national repeat cross-sectional surveys.. Lancet regional health. Americas, 55, 101373. https://doi.org/10.1016/j.lana.2026.101373