Medical Marijuana Policy and the Initiation of Marijuana Use Among Young People

With medical marijuana laws already enacted in almost half of U.S. states, and the number that have legalized medical or recreational use increasing annually, it is important to understand the effects of medical marijuana policy.  Young people are at particular risk for the onset of substance use, and earlier use is associated with poorer outcomes.  Youth and young adults could be influenced to start using marijuana by the increased availability and destigmatization of use that medical marijuana laws may contribute to.  To examine the potential effects of medical marijuana policy on youth and young adult initiation of marijuana use, we analyzed 10 years of individual-level data from the NSDUH, combined with state-level economic and social indicators and information about marijuana laws. We stratified our sample into youth of middle school age and high school age, and young adults 18-25, thereby measuring developmentally appropriate age groups.  To account for the possibility that states that pass medical marijuana laws differ in other ways from those that do not, we also included state-level fixed effects in our logistic regression modeling.  These models, including individual- and state-level controls alongside the state-level fixed effects, revealed no significant effects of living in a medical marijuana state on past month marijuana use.  However, for past year initiation of marijuana use, we found a significant odds ratio for medical marijuana state residence among young adults, indicating that 18-25 year olds who lived in medical marijuana states had greater odds of initiating marijuana use than those who did not.  Whereas past month marijuana use was higher among older age groups at the national level, with young adults the most likely to have used over the past 30 days, initiation of marijuana (e.g., using for the first time within the past year) followed a different pattern, with first-time use most common within the high school age group.  This broader pattern of initiation combined with our regression findings suggests that young adults who have already chosen not to try marijuana during their high school years when initiation was most common among their peers are more likely to try it in young adulthood if they live in a medical marijuana state.  Thus our results suggest that young adults who might not have otherwise begun to use could be more likely to do so if they live in a state with medical marijuana laws.