Adolescent treatment admissions for marijuana following recreational legalization in Colorado and Washington Jeremy Mennis, Gerald J. Stahler, 2020

Adolescent treatment admissions for marijuana following recreational legalization in Colorado and Washington

Jeremy Mennis, Gerald J. Stahler

Drug and Alcohol Dependence, 2020, 210, 107960

Doi : 10.1016/j.drugalcdep.2020.107960



Introduction : There is concern that recreational marijuana legalization (RML) may lead to increased cannabis use disorder (CUD) among youth due to increased marijuana use. This study investigates whether adolescent substance use disorder treatment admissions for marijuana use increased in Colorado and Washington following RML.

Methods : Annual data on 2008–2017 treatment admissions for marijuana use from the SAMHSA TEDS-A dataset for adolescents age 12–17 were used to model state treatment admissions trends. Difference-in-differences models were used to investigate whether treatment admissions increased following RML in Colorado/Washington compared to non-RML states, after adjusting for socioeconomic characteristics and treatment availability.

Results : Over all states in the analysis, the rate of adolescent treatment admissions for marijuana use declined significantly over the study period (β=−3.375, 95 % CI=−4.842, −1.907), with the mean rate falling nearly in half. The decline in admissions rate was greater in Colorado and Washington compared to non-RML states following RML, though this difference was not significant (β=-7.671, 95 % CI=-38.798, 23.456).

Conclusion : Adolescent treatment admissions for marijuana use did not increase in Colorado and Washington following RML. This may be because youth marijuana use did not increase, CUD did not increase (even if use did increase), or treatment seeking behaviors changed due to shifts in attitudes and perceptions of risk towards marijuana use.

Keywords : Marijuana, Cannabis, Adolescent, Substance use disorder, Cannabis use disorder


1. Introduction

Cannabis use disorder (CUD) in adolescence is associated with mental health problems and other negative outcomes which can persist into adulthood (Kosty et al., 2016; Volkow et al., 2014). Because heavy marijuana use is a risk factor for CUD (Volkow et al., 2014), there is substantial concern that the growth of recreational marijuana legalization (RML) in the US and elsewhere will lead to a higher prevalence of CUD among youth due to increasing marijuana use (Hall and Lynskey, 2016). Though national survey data indicate that youth marijuana use generally has not increased over the past two decades (Miech et al., 2019), youth are now more permissive of use and far less likely to perceive marijuana use as harmful than in the past (Keyes et al., 2016; Sarvet et al., 2018b; Schmidt et al., 2016). Although the legal age to purchase marijuana is 21 in states currently enacting RML, recreational legalization may make marijuana more accessible to youth through purchases by older friends and family, expose youth to marijuana advertising, and enhance pro-social norms around marijuana use (Harpin et al., 2018; Lipperman-Kreda and Grube, 2018; Trangenstein et al., 2019). Consequently, RML may affect attitudes towards marijuana, as well as the age of initiation, prevalence, and frequency of use (D’Amico et al., 2018; Palamar et al., 2014), potentially resulting in higher levels of CUD among adolescents (Han et al., 2018).

Though recent reviews of research indicate that medical marijuana legalization (MML) is not associated with increasing adolescent marijuana use or CUD (Leung et al., 2018; Sarvet et al., 2018a), related research on RML is so far mixed, with some researchers finding no increase in adolescent marijuana use following RML (Anderson et al., 2019; Dilley et al., 2019), others finding evidence of increasing use in certain states (Cerda et al., 2017; Rusby et al., 2018), and still others finding a small increase in CUD (Cerda et al., 2019). These differing results may be due to the use of different data sets capturing marijuana use and dependence, differing methodological approaches, variation in state contexts and marijuana regulatory frameworks, as well as simply a potential lag between the implementation of RML and its effects on adolescent marijuana use (Leung et al., 2018; Pacula et al., 2015).

If RML does increase CUD among youth, one potential consequence would be an increased need for treatment. To our knowledge, however, no studies thus far have examined changes in treatment admissions for marijuana use among youth following RML. Here, we investigate whether RML was associated with an increase in adolescent treatment admissions for marijuana use in Colorado and Washington, the first US states to enact RML, in late 2012, which thus provide the longest post- RML time period of all US states for analysis of youth treatment admissions trends. Using differences-in-differences analysis, this study compares treatment admissions trajectories in Colorado and Washington before and after RML enactment to states that did not enact RML.