In a research letter published today in JAMA Pediatrics, a group of university economists found that cannabis use among youth has declined in states that adopted adult-use legalization.
The researchers used 25 years of data from Youth Risk Behavior Surveys (YRBS), which are administered to all US high-school students every two years. The surveys, run by the federal Centers for Disease Control, track behaviors such as diet, exercise, sexual activity, and the use of alcohol, tobacco, and other drugs. Since 1991, the YRBS has collected data from more than 4.4 million high school students.
The study was led by Montana State University economist D. Mark Anderson, with contributions from colleagues at the University of Oregon, the University of Colorado, and San Diego State University.
Youth Use Down 8%
By comparing medical marijuana states, legal adult-use states, and prohibition states, the economists found that medical legalization did not affect youth use of cannabis. But in adult-use states, the researchers found an 8% decrease in youth cannabis use and a 9% decrease in frequent youth cannabis use. In this context, “use” was defined as consuming cannabis once in the past 30 days; “frequent use” was defined as consuming 10 times in the past 30 days.
“Consistent with the results of previous researchers, there was no evidence that the legalization of medical marijuana encourages marijuana use among youth,” wrote the authors. “Moreover, the estimates reported [by the Youth Risk Behavior Surveys] showed that marijuana use among youth may actually decline after legalization for recreational purposes.”
Putting Weed Dealers Out of Business
Anderson and colleagues posit that their findings were consistent with the argument that “it is more difficult for teenagers to obtain marijuana as drug dealers are replaced by licensed dispensaries that require proof of age.”
Today’s published research letter is consistent with previous studies that found decreased youth cannabis use following the legalization of medical and adult-use marijuana. A 2014 report by the National Bureau of Economic Research stated: “Our results are not consistent with the hypothesis that legalization leads to increased use of marijuana by teenagers.”
Youth Use Decreasing Since 2002
Federally funded surveys of teens, such as the Youth Risk survey, have found rates of youth cannabis use among minors aged 12 to 17 have decreased since 2002, the dawn of medical cannabis dispensaries in the United States.
In California, independent survey data show cannabis use among seventh-grade students dropped 47% from 2013 to 2017—a time when hundreds of medical cannabis dispensaries were operating around the state. These and other studies can be found in Leafly’s recent report, Debunking Dispensary Myths.