Does Recreational Marijuana Legalization Increase Substance Use Disorders for Cocaine, Opioids, or Methamphetamines? Evidence from Colorado and Washington

Authors: Jeremy Mennis*, Temple University, Gerald J Stahler, Temple University, Michael Mason, University of Tennessee Knoxville
Topics: Medical and Health Geography, Spatial Analysis & Modeling
Keywords: marijuana, cannabis, substance use disorder, treatment
Session Type: Virtual Paper
Presentation File: No File Uploaded


Marijuana policy has long been influenced by the idea that marijuana use is associated with the use of harder drugs, i.e. the idea that marijuana acts as a ‘gateway’ drug. If so, there is concern that recreational marijuana legalization (RML) may lead to corresponding increases in substance use, and, consequently, substance use disorders (SUDs), for illicit drugs other than marijuana. This study investigates whether SUD treatment admissions for cocaine, opioids, and methamphetamines increased following RML in Colorado and Washington. Annual 2008-2017 treatment admissions data from the SAMHSA Treatment Episode Dataset – Admissions (TEDS-A) are entered into difference-in-differences models, adjusted for state-year level covariates, to investigate whether the difference in cocaine, opioids, and methamphetamines treatment admissions before versus after RML differed between Colorado and Washington and a set of control states without RML for different age groups. Results indicate that there is no significant difference (p<0.05) between Colorado and Washington and the control states in the pre- versus post-legalization trajectories of SUD treatment admissions for cocaine, opioids, or methamphetamines, for adolescents or adults. We conclude that RML in Washington and Colorado did not result in increased SUD treatment admissions for non-marijuana illicit drug use. Future research should extend this research to other states and over longer timer periods.

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