State Medical Marijuana Laws and Initiation of Cigarettes among Adolescents in the U.S., 1991-2015.

Objective: Although cigarette use has declined among adolescents, marijuana use has increased in subgroups of this population. The association between medical marijuana laws (MMLs) and cigarette initiation among adolescents, however, needs further examination. We investigated the association between MMLs and age of cigarette initiation and stratified findings by gender, race/ethnicity, and state dispensary status.

Method: Data were from N=939,725 adolescents in 9-12 grade living in 46 states who participated in the Youth Risk Behavior Surveillance System between 1991-2015. Participants were asked the age they first smoked a cigarette and other sociodemographic characteristics. States were categorized as MML states if they had legalized marijuana for medicinal purposes by 2015. We used a difference-in-difference methodology and logistic regressions to assess the relationship between MMLs and cigarette initiation.

Results: Our results indicate lower odds of initiating cigarettes, in every age group (8 years old or younger, 9-10, 11-12, 13-14, 15-16, 17 years old or older) in states with MMLs when compared to non-MML states. After stratification, we find lower odds of cigarette initiation in certain age groups by gender, race/ethnicity, and state dispensary status. We report no difference in state MML implementation and age of cigarette initiation among Hispanic adolescents in every age group, and Black adolescents 8 years or younger and 17 years or older.

Conclusions: Cigarette initiation has decreased among adolescents in MML states compared with those in non-MML states. Further research should evaluate how MMLs and recreational marijuana policies are associated with e-cigarette initiation and use.