Social
Impacts of Quebec’s Minimum Legal Age for Cannabis Use: A Difference-in-Discontinuities Approach Sarah Windle* Sarah Windle Windle Windle Windle McGill University
Background: While countries worldwide are liberalizing access to cannabis, few studies have examined the impact of the cannabis minimum legal age (MLA) on the initiation, prevalence, and frequency of substance use among youth and young adults. In Canada, non-medical cannabis use was legalized in 2018, with varying MLAs (18 in Quebec and Alberta, 19 in other provinces). Quebec is the only province to have changed its MLA since legalization, increasing from 18 to 21 in 2020.
Methods: We will use annual cross-sectional Quebec Cannabis Survey data (2018-2014) to examine the impact of new legal access to cannabis (at age 18 or 21), as well as responsiveness to changes in the MLA (e.g., losing and regaining access to legal cannabis), on cannabis use among youth and young adults, using a difference-in-discontinuities approach (i.e., differenced regression discontinuities). This approach identifies a “treated” discontinuity (e.g., the difference in cannabis use between 17- and 18-year-olds in 2019) and a “control” discontinuity (e.g., the difference in cannabis use between 17- and 18-year-olds in 2018 [pre-legalization]). By differencing these discontinuities (similar to a difference-in-differences approach), we remove the increase in cannabis use that would be expected due to secular trends and legal access to alcohol. Each survey year will be analysed separately, providing different information concerning policy impacts (e.g., new/losing/regaining access to legal cannabis). We will apply sampling and bootstrap weights, and consider heterogeneity by sociodemographic characteristics.
Significance: Quebec’s unique cannabis MLA changes offer the opportunity to consider the impacts of MLA selection, providing evidence for whether the cannabis MLA is effective in delaying cannabis use for some youth and young adults, and whether these individuals reduce cannabis consumption in response to an increase in MLA. Lessons learned are relevant to global cannabis policy decision-making.