New study shows legalization appears to have had little effect on cannabis use among adolescents

A new study published in the American Journal of Public Health found little effect of adult-use marijuana laws on prevalence of marijuana use among youth.

In this examination, researchers focused specifically on 504 justice system-involved adolescents in California, who, as they point out, have substantially higher marijuana use levels as compared to the general youth population. Among this population, they found marijuana use levels in the past 24 hours were similar in 2015 (before adult-use marijuana was legalized) and in 2018 (after adult-use marijuana was legalized and implemented in the state).

The authors then compared the findings of the California youth population with a group of justice system-involved adolescents in Pennsylvania, a state that has not legalized cannabis for adult use and had lower levels of marijuana use than in California at baseline. If adult-use legalization laws increased adolescent marijuana use, the gap in marijuana use prevalence across the groups in the two states would be expected to grow. However, the gap actually grew smaller because marijuana prevalence increased relatively faster among the Pennsylvania adolescents.

As a whole, the study suggests that marijuana legalization has not had much overall effect on youth marijuana use during the past two decades. Over the past 10 years, state marijuana laws have changed substantially, with 11 states and D.C. legalizing cannabis for adults. Nonetheless, youth use rates have remained quite steady, indicating that major changes in the legality of marijuana across the U.S. have not impacted adolescent use.

The abstract of the study, “Marijuana use among justice-involved youths after California statewide legalization, 2015-2018,” appears here, and an accompanying editorial, “Marijuana legalization and marijuana prevalence among adolescents,” can be found here.