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Teenagers Are Less Likely to Use Cannabis When It’s Legal, Study Finds

By Leo Bear-McGuinness

Published: Jul 09, 2019   
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Marijuana use among teenagers may actually decline after recreational legalization, according to new research. 

Published in the American Medical Association, the new study also claims that there is no evidence that the legalization of medical marijuana encourages cannabis use among young people.  

States that legalized recreational cannabis were associated with an 8 percent fall in the number of high school-age teenagers who claimed they used cannabis in the last 30 days, and a 9 percent drop in the number who said they'd consumed the drug at least 10 times in the last 30 days. 

“I think the big takeaway is that we find no evidence that teen marijuana use goes up after legalization for medicinal or recreational purposes,” Mark Anderson, an associate professor at Montana State University and lead author of the study, told Analytical Cannabis.

“We view this as a very important result from a policy perspective because opponents often claim that teen use will skyrocket after these laws are passed. Based on our analysis, this has simply not been the case.”

Although Anderson and the other authors don't give a detailed reason as to why cannabis use may be declining in legalized states in the paper, they do state that “it is more difficult for teenagers to obtain marijuana as drug dealers are replaced by licensed dispensaries that require proof of age.”

Previous research efforts have also concluded that the legalization of cannabis can help reduce the proportion of teenagers consuming the drug. One study in Washington – one of the first states to legalize marijuana for retail sale – showed that use went down significantly among 8th and 10th graders after legalization. Although, other studies have demonstrated legalization may be significantly increasing cannabis use in young people over the age of 18. 

The study’s authors used data from across 27 states drawn from Youth Risk Behavior surveys conducted from 1993 to 2017. More than 1.4 million high school students’ results were included in the final analysis, and researchers examined the responses before and after cannabis laws were implemented. 

“We observed pre- and post-treatment data for 27 medical marijuana states and DC, and we observed pre- and post-treatment data for 7 recreational marijuana states. The remaining states in the analysis serve as controls,” Anderson explained. 

“To our knowledge, no other study in the literature has leveraged this amount of policy variation. As a result, we view our estimates as the most credible to date.”

But while more comprehensive than most of its peer papers, Anderson did admit that the study has its limitations. After all, the association concluded in the study is not necessarily a causal relationship, and more research will be needed to determine why this association exists.

“Because the recreational marijuana laws are so recent, we observed limited amounts of post-treatment data for some of these states,” Anderson continued. “It would make sense for us to update these estimates in a few years when more data have become available.”

Other investigations into how teenagers’ cannabis consumption rates have changed in legalized states have also been less conclusive. A 2018 report from the Colorado Division of Criminal Justice Office of Research and Statistics found that the proportion of high school students in the state – which legalized adult cannabis use in 2014 – who claimed to have used marijuana in their lifetime or over the past 30 days remained statistically unchanged from 2005 to 2017.

Leo Bear-McGuinness

Science Writer & Editor

Leo joined Analytical Cannabis in 2019. From research to regulations and analysis to agriculture, his writing covers all the need-to-know news for the cannabis industry. He holds a Bachelor's in Biology from Newcastle University and a Master's in Science Communication from the University of Edinburgh.


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