Session: Abstract of Distinction: Adolescent Marijuana Use amidst Reformed State-Level Marijuana Laws (Society for Prevention Research 26th Annual Meeting)

If a prevention scientist had been told in 1995 that the next 20 years would include several states adopting MMLs (medical marijuana laws) and RMLs (recreational marijuana laws), that person would likely have predicted that adolescent marijuana would increase. And yet, as of 2017, the best evidence suggests that MMLs have not led to increases in adolescent use. It is too early to draw conclusions about RMLs.

Marijuana use among US adolescents is common (20% of high school students and 28% of 12th graders report past 30-day use) and has been relatively stable over time, even despite rapid policy changes. In fact, past 30-day use decreased slightly from 27% in 1999 to 22% in 2015, a period during which several states passed MMLs and/or RMLs.

Collectively, the studies to be presented as part of this symposium (see below) show that changes in adolescent marijuana use vary by grade level, and suggest that use among 12th graders may be increasing. Our findings are consistent with Twenge and Park’s “slow development theory.” This theory suggests that early adolescents (i.e., 6th-8th graders) are increasingly less likely to engage is “adult activities,” such as substance use.

Given rapidly changing state marijuana policies, it is important to examine the nature of marijuana use among adolescents, and consider changes within the context of adolescent development. This symposium includes three studies based on population-based state samples of adolescents. The foundational knowledge stemming from our work can be used to inform programming and policy development efforts to prevent adolescent MU in a post-prohibition society. An expert in substance use epidemiology will serve as a discussant, whose role will be to summarize observations across the three presentations, to describe implications for prevention and policy, and to identify areas for future research.

In the first presentation, we examine grade-level differences in Colorado high school students' use of alternative modes of marijuana consumption, including edibles and vaporizers. Data are from the 2015 Healthy Kids Colorado Survey, a biennial, statewide survey of Colorado high school students.

In the second presentation, we use data from Washington State's Healthy Youth Survey to compare trends in marijuana use among 8th, 10th, and 12th graders from 2004-2016. We also explore differences by sex and race/ethnicity.

In the third presentation, we use quasi-experimental methods to examine the impact of MMLs on marijuana use among 9th-12th graders in 46 states and describe differences by grade level. Data are from state YRBS surveys (1991-2015). We also investigate the impact of specific provisions of MMLs (e.g. possession limits).