Session: Substance Use and Risk Factors in Youth before and after Marijuana-Related Legislation in Washington State (Society for Prevention Research 23rd Annual Meeting)

The recent legalization of recreational marijuana use for those over 21 years of age in Washington and other states, along with the medical marijuana laws of earlier decades, have changed the legal and normative context for generations of youth. One of the primary concerns for public health is that legalization may lead to more favorable attitudes and norms about substance use, and greater availability of marijuana, which have been shown to predict increased adolescent marijuana and other substance use. Increased adolescent substance use has been in turn associated with a range of negative outcomes. Understanding the impact of these legislative changes on substance use and malleable risk factors is a prerequisite for the design and implementation of effective prevention and intervention services. The three studies included in this symposium examine the changes in substance use and proximal risk factors before and after medical (MML) and recreational marijuana legislation (RML) in Washington State, and the knowledge young people have about the marijuana legislation, testing for differences between marijuana users and non-users.

Specifically, Study 1 used state-wide student data to examine changes in adolescent substance use and proximal risk factors for substance use before and after the passage of MML. The results indicate that the prevalence of alcohol, marijuana, and tobacco use was significantly higher in the spring of 1998 – before-MML – than at any of the post-MML time points and the perception of harm from marijuana use was higher in the years after MML than before. However, an increase in prevalence of those indicating being unsure about harmfulness of marijuana use at the time point immediately after MML was also evidenced, but this trend was reversed in the following years.

Study 2 used a sample of adolescents from Tacoma, WA and compared rates of marijuana and other substance use across two cohorts who experienced RML at different ages. The results provide partial evidence for the substitution hypothesis that under RML marijuana may replace other substances.

Study 3 involves a sample of over 800 youth and young adults from WA State who have been completing bi-annual assessments since 2012. The study examines the general understanding of, support for, and perceptions surrounding federal and WA state marijuana-related laws and the impact this may have on individual use.

Discussant, who is a Federal employee, will discuss the importance of these findings for public policy and prevention efforts.