JAMA Study Finds “Little Evidence” of Link Between Cannabis Legalization and Youth Use

A new, updated study published Monday in the JAMA Network Open found “little evidence” that adult and medical use cannabis legalization “encourage youth marijuana use.” 

The study, conducted by researchers from the Department of Agricultural Economics at Montana State University, comes at a time when America is approaching a tipping point on legalization for adult use, with 19 states and Washington D.C. having enacted such reforms. And today, 36 states allow for medical use of cannabis, with programs that vary in the scope of their restrictions. 

The authors updated previous research by expanding their dataset from the Youth Risk Behavior to include 1993 through 2019. In this new study, they called into “question the generalizability of their results” from a previous study that looked at data only until 2017.  California became the first state in the nation to cannabis for medical use in 1996, with an extremely permissive law, which started a domino effect of reform across the country that has picked up speed over the years. Between 2017 and 2019, for example, a half dozen states legalized cannabis for medical or adult use, and the states that had legalized just before then, such as California in 2016, saw their programs take shape.

“Consistent with estimates from prior studies, there was little evidence that [recreational marijuana laws] or [medical marijuana laws] encourage youth marijuana use,” researchers concluded, adding at the “the overall association between [recreational marijuana law] adoption and marijuana use among was statistically indistinguishable from zero.” 

The authors acknowledge one limitation of the study, which is that legalization and various laws are “a relatively new phenomenon.” 

“As more post legalization data become available, researchers will be able to draw firmer conclusions about the relationship between [recreational marijuana laws] and adolescent marijuana use,” researchers noted. 

Concerns over cannabis and youth use have come up during recent cannabis-related hearings in Congress. In January 2020, the House Energy and Commerce Subcommittee on Health held a hearing called “Cannabis Policies for the New Decade,” which focused on hurdles related to cannabis research. Nora Volkow, director of the National Institute on Drug Abuse, used her testimony at this hearing to explain how cannabis works in the body, and to highlight two main concerns: cannabis use by pregnant people, and youth use. 

“However, our understanding of the adverse effects of cannabis is incomplete,” Volkow said. 

During this hearing, Volkow was asked several times about whether cannabis was a gateway drug, to which Volkow responded, “It increases the likelihood that you are sensitive to the addictive effects of other drugs.” 

The JAMA Network Open study was funded in part by a Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health (NIH) research infrastructure grant, the Center for Studies in Demography and Ecology at the University of Washington, and two authors were supported in part by the Center for Health Economics & Policy Studies (CHEPS) at San Diego State University, which included grant funding received from the Charles Koch Foundation.

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