Recreational Marijuana Legalization and Adolescent Use of Marijuana, Tobacco, and Alcohol

Purpose: Given the rapid expansion of recreational marijuana legalization (RML) polices, it is essential to assess whether such policies are associated with shifts in the use of marijuana and other substances, particularly for adolescents, who are uniquely susceptible to negative repercussions of marijuana use. This analysis seeks to provide greater generalizability, specificity, and methodological rigor than limited prior evidence. Methods: Youth Risk Behavior Survey data from 47 states from 1999 to 2017 assessed marijuana, alcohol, cigarette, and e-cigarette use among adolescents (14-18 & thorn; years; N = 1,077,938). Associations between RML and adolescent past-month substance use were analyzed using quasi experimental difference-in-differences zero-inflated negative binomial models. Results: Controlling for other state substance policies, year and state fixed effects, and adolescent demographic characteristics, models found that RML was not associated with a significant shift in the likelihood of marijuana use but predicted a small significant decline in the level of marijuana use among users (incidence rate ratio = .844, 95% confidence interval [.720-.989]) and a small increase in the likelihood of any e-cigarette use (odds ratio of zero use = .647, 95% confidence interval [.515-.812]). Patterns did not vary over adolescent age or sex, with minimal differences across racial/ethnic groups. Conclusions: Results suggest minimal short-term effects of RML on adolescent substance use, with small declines in marijuana use and increase in the likelihood of any e-cigarette use. Given the delayed rollout of commercial marijuana sales in RML states and rapid expansion of RML policies, ongoing assessment of the consequences for adolescent substance use and related health and behavioral repercussions is essential. (c) 2020 Society for Adolescent Health and Medicine. All rights reserved.