Examining the Potential Impact of Recreational Cannabis Legalization on Individuals Receiving Treatment for Substance Use Disorder: An Interrupted Time Series Study in Guelph, Ontario, Canada

Abstract

Objective: The present research evaluated the impact of legalizing recreational cannabis among individuals with substance use disorders (SUD) who may already use cannabis at high rates.

Methods: Using an interrupted time series study design, we evaluated the potential impact of legalization among individuals seeking treatment for SUD within a hospital-based treatment setting in Guelph, Ontario. We examined 2,925 individuals who entered the treatment program between April 2017 and December 2021. We performed segmented regression analyses using both the date of cannabis legalization and the date of edibles legalization as the interruption time point. We also performed stratified analyses to examine potential sex differences.

Results: We found no significant changes in the prevalence of cannabis use or readiness to quit using cannabis following legalization with either of the interruption time points. However, there was evidence of increasing CUD severity post-edibles legalization. Stratified analyses also suggested possible sex differences in readiness to quit over time.

Conclusions: Results point to some small but potentially important impacts of recreational cannabis legalization among individuals with SUD that may only continue with time. Nevertheless, there is a need to continue to monitor cannabis use trends to understand any potential lagged effects.