Adolescent Cannabis Use and Perceived Social Norms Trends Pre- and Post- Implementation of Washington State's Liberalized Recreational Cannabis Policies (LRCP): Healthy Youth Survey, 2002-2016.

Introduction: This study examines trends in adolescent perceptions of social norms pertaining to adolescent cannabis use, stratified by type of social norm (community, parent, peer, or self) and grade. Trends are examined in relation to past 30-day adolescent cannabis use, and are interpreted in light of the passing of liberalized recreational cannabis policies (LRCP: 2012) in the state from which the data were derived.

Methods: Data for this study come from the Washington State Healthy Youth Survey (HYS). Data collection took place during even numbered years between 2002-2016, with methods-stabilized school surveys of school-attending youths in grades 8, 10, and 12. This study uses an aggregate sample size n=154,808 surveys (2002-16 state representative samples; included only those with complete data pertaining to social norms and 30-day cannabis use). Estimated year-specific social norms and cannabis use prevalence proportions are estimated for the state as a whole, and stratified by grade. Regression analyses assessed the association between social norms and recent cannabis use.

Results: The proportion of recent adolescent cannabis use during the initial years post-LRCP (2012) in Washington State have remained relatively stable, or trended downward slightly. Proportions reflecting perceived social acceptance varied by the type of social norm. Cannabis use by close friend (friend acceptance) has continued to mirror adolescent cannabis use. The trend lines representing the prevalence of youth who report that the majority of their best friends use cannabis began to decline in 2010 among 10^th and 12^th graders, and in 2012 among 8^th graders. This downward trend has continued through 2016. The proportion of youth reporting parental acceptance of, and overall community acceptance of, adolescent cannabis use have remained fairly low, and fairly stable from pre- to post- passing of Washington’s LRCP (2012). Adolescents’ self-perceptions that cannabis use is “not wrong at all” increased steadily for high school students between 2004 and 2014, but edged downward in 2016. All types of social norms remained statistically predictive of adolescent cannabis use (p>0.05).

Conclusion: LRCP enactment in Washington State was not followed by an immediate increased use of cannabis among adolescents. As debate continues in the United States regarding the pros and cons of LRCPs, data pertaining to outcomes in states that have previously passed such laws will help guide lawmakers and the public. Knowledge regarding changes in risk factors associated with the passing of such laws will also be important to optimize appropriate prevention programs aimed at continuing to reduce the incidence of youth substance use.