Authors of a new research letter published by the Journal of the American Medical Association (JAMA) on Wednesday said there’s no evidence that states’ adoption of laws to legalize and regulate marijuana for adults has led to an increase in youth use of cannabis.

To arrive at the results, researchers at Montana State University and San Diego State University took responses from the Youth Risk Behavior Survey (YRBS), which asks high-school students about various health-related activities. The report explains that the four-author team analyzed results from 207,781 respondents.

Findings showed that states’ adoption of recreational marijuana laws (RMLs) had no association with the prevalence of youth cannabis consumption.

“In this repeated cross-sectional study, there was no evidence that RMLs were associated with encouraging youth marijuana use,” the two-page paper published in JAMA Psychiatry says. “After legalization, there was no evidence of an increase in marijuana use.”

Nor did the opening of marijuana retail stores seem to impact youth use. “Estimates based on the state YRBS and estimates of the association between the first dispensary opening and marijuana use were qualitatively similar,” the team wrote.

“Legalization was not associated with current marijuana use or frequent marijuana use.”

Authors wrote that, in their study, “more policy variation was captured than in any prior study on RMLs and youth marijuana use.” Pre- and post-legalization data were available for 12 states, and nine contributed data from before and after retail sales began. Data also included 36 states without adult-use cannabis laws.

The data come on the heels of another JAMA-published study earlier this month that found that neither legalization nor the opening of retail stores led to increases in youth cannabis use.

That study, published in the journal JAMA Pediatrics, concluded that the reforms were actually associated with more young people reporting not using marijuana, along with increases in those who say they don’t use alcohol or vape products either.

Passage of recreational cannabis laws (RCL) “was not associated with adolescents’ likelihood or frequency of cannabis use,” found the analysis by researchers at Boston College and the University of Maryland at College Park. Nor was the opening of retail stores associated with increases in youth use.

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Over time, that study suggested, adult-use marijuana laws, in fact, led to lower odds of any cannabis use. “Each additional year of RCL,” it says, “was associated with 8% higher odds of zero cannabis use (lower likelihood of any use), with non-significant total estimates.”

“Results,” that study concluded, “suggest that legalization and greater control over cannabis markets have not facilitated adolescents’ entry into substance use.”

The subject of youth use has been a contentious topic as more states consider legalizing marijuana, with opponents and supporters of the reform often disagreeing on how to interpret the results of various studies, especially in light of the sometimes mixed results in the latest JAMA paper and others.

Recently released data from a Washington State survey of adolescent and teenage students found overall declines in both lifetime and past-30-day marijuana use since legalizations, with striking drops in recent years that held steady through 2023. The results also indicate that the perceived ease of access to cannabis among underage students has generally fallen since the state enacted legalization for adults in 2012.

A separate study late last year also found that Canadian high-school students reported it was more difficult to access marijuana since the government legalized the drug nationwide in 2019. The prevalence of current cannabis use also fell during the study period, from 12.7 percent in 2018–19 to 7.5 percent in 2020–21, even as retail sales of marijuana expanded across the country.

In December, meanwhile, a U.S. health official said that teen marijuana use has not increased “even as state legalization has proliferated across the country.”

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“There have been no substantial increases at all,” said Marsha Lopez, chief of the National Institute on Drug Abuse’s (NIDA) epidemiological research branch. “In fact, they have not reported an increase in perceived availability either, which is kind of interesting.”

Another earlier analysis from the CDC found that rates of current and lifetime cannabis use among high school students have continued to drop amid the legalization movement.

A study of high school students in Massachusetts that was published last November found that youth in that state were no more likely to use marijuana after legalization, though more students perceived their parents as cannabis consumers after the policy change.

A separate NIDA-funded study published in the American Journal of Preventive Medicine in 2022 also found that state-level cannabis legalization was not associated with increased youth use. The study demonstrated that “youth who spent more of their adolescence under legalization were no more or less likely to have used cannabis at age 15 years than adolescents who spent little or no time under legalization.”

Yet another 2022 study from Michigan State University researchers, published in the journal PLOS One, found that “cannabis retail sales might be followed by the increased occurrence of cannabis onsets for older adults” in legal states, “but not for underage persons who cannot buy cannabis products in a retail outlet.”

The trends were observed despite adult use of marijuana and certain psychedelics reaching “historic highs” in 2022, according to separate data released last year.

Written by Ben Adlin for Marijuana Moment | Featured image by Gina Coleman/Weedmaps

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