Adult use cannabis legalization and cannabis use disorder treatment in California, 2010-2021.

ABSTRACT

INTRODUCTION: Many nations and jurisdictions have legalized non-medical adult use of cannabis, or are considering doing so. This paper contributes to knowledge of adult use legalization's associations with cannabis use disorder (CUD) treatment utilization. METHODS: This study collected data from a dataset of all publicly funded substance use disorder treatment delivered in California from 2010 to 2021 (1,460,066 episodes). A logistic regression model estimates adult use legalization's impacts on CUD treatment utilization using an individual-level pre-post time series model, including individual and county-level characteristics and county and year-fixed effects. RESULTS: Adult use legalization was associated with a significant decrease in the probability of admission to CUD treatment (average marginal effect (AME) -0.005, 95 % CI -0.009, 0.000). Adult use legalization was also associated with a decrease in the probability of admission to CUD treatment for males (AME -0.025, 95 % CI -0.027, -0.023) Medi-Cal beneficiaries (AME -0.025, 95 % CI -0.027, -0.023) adults ages 21+ (AME -0.011, 95 % CI -0.014, -0.009) and Whites (AME -0.012, 95 % CI -0.015, -0.010), and an increase in the probability of admission to CUD treatment for patients referred from the criminal justice system (AME 0.017, 95 % CI 0.015, 0.020) and Blacks (AME 0.004, 95 % CI 0.000, 0.007) and Hispanics (AME 0.009, 95 % CI 0.006, 0.011). CONCLUSIONS: Adult use legalization is associated with declining CUD treatment admissions, even though cannabis-related problems are becoming more prevalent. Policies and practices that protect public health, and engage people with CUD in treatment are needed.