LAUSR

INTRODUCTION The legalisation of cannabis in Canada in 2018, and subsequent increase in prevalence of use, has generated interest in understanding potential changes in problematic patterns of use, including by socio-demographic factors such as race/ethnicity and neighbourhood deprivation level. METHODS This study used repeat cross-sectional data from three waves of the International Cannabis Policy Study web-based survey. Data were collected from respondents aged 16-65 prior to cannabis legalisation in 2018 (n = 8704), and post-legalisation in 2019 (n = 12,236) and 2020 (n = 12,815). Respondents' postal codes were linked to the INSPQ neighbourhood deprivation index. Multinomial regression models examined differences in problematic use by socio-demographic and socio-economic factors and over time. RESULTS No evidence of a change in the proportion of those aged 16-65 in Canada whose cannabis use would be classified as 'high risk' was noted from before cannabis legalisation (2018 = 1.5%) to 12 or 24 months after legalisation (2019 = 1.5%, 2020 = 1.6%; F = 0.17, p = 0.96). Problematic use differed by socio-demographic factors. For example, consumers from the most materially deprived neighbourhoods were more likely to experience 'moderate' vs 'low risk' compared to those living outside deprived neighbourhoods (p < 0.01 for all). Results were mixed for race/ethnicity and comparisons for high risk were limited by small sample sizes for some groups. Differences across subgroups were consistent from 2018 to 2020. DISCUSSION AND CONCLUSIONS The risk of problematic cannabis use does not appear to have increased in the 2 years following cannabis legalisation in Canada. Disparities in problematic use persisted, with some racial minority and marginalised groups experiencing higher risk.