Heterogeneity of state medical marijuana laws and adolescent recent use of alcohol and marijuana: Analysis of 45 states, 1991-2011.

OBJECTIVE

To assess associations between enactment of state medical marijuana laws (MMLs), MML restrictiveness, and past-30-day youth alcohol use overall, and in relation to marijuana use.

METHOD

This quasi-experimental difference-in-difference designed study used state-level Youth Risk Behavior Survey data of 9th-12th grade students in 45 states from 1991-2011 (N D 715,014). We conducted bivariate (unadjusted) and multivariable (adjusted for state, year, individual characteristics) logistic regression analyses to examine the effect of MML enactment (yes/no) and less restrictive vs. more restrictive MMLs on five varying measures of past 30-day alcohol use (i.e., any use or binge) and alcohol and marijuana use behaviors.

RESULTS

In the final adjusted analyses, MML enactment was associated with lower odds of adolescent past 30-day (1) alcohol use (OR D 0.92, [0.87, 0.97], p < .01) and (2) use of both alcohol and marijuana (OR D 0.93, [0.87, 0.99], p < .05). States with less restrictive MMLs had lower odds of past 30-day (1) alcohol use (OR D 0.94, [0.92, 0.97], p < .001), (2) binge drinking (OR D 0.96, [0.93, 0.97], p < .05), (3) alcohol use without any marijuana use (OR D 0.96, [0.93, 0.99], p < .01), and (4) use of both alcohol and marijuana (OR D 0.96, [0.92, 0.99], p < .05).

CONCLUSIONS

This study found that enactment of any MML, and of less restrictive MMLs, was associated with lower odds of past 30-day adolescent alcohol use among adolescents. With continued change in state marijuana laws, it is important to monitor the effect of their enactment and implementation, as well as their specific provisions (e.g. dispensaries, home cultivation), which may differentially affect adolescent behaviors.