A new report published by the the American Medical Association (AMA) finds that neither adult-use marijuana legalization nor the opening of retail stores in U.S. states led to increases in youth cannabis use. Rather, the reforms were generally 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.
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The results of the study, published on Monday in the medical group’s journal JAMA Pediatrics, reinforce previous findings that legalizing and regulating marijuana for adults, typically does not increase youth use of the substance—contrary to what opponents of the policy change often argue.
The study drew from data in 47 states, looking at responses from 898,271 teens. “With parent consent,” authors explained, “students from ninth to twelfth grade self-reported prior month use of cannabis, alcohol, cigarettes, and e-cigarettes.”
Marijuana Consumers Have "Significantly Decreased Odds" Of Cognitive Decline
Passage of recreational cannabis laws (RCL) “was not associated with adolescents’ likelihood or frequency of cannabis use,” the analysis found, “although negative total effect estimates indicated significantly lowered use following RCL.” Nor were increases associated with the launch of recreational cannabis retail sales (RCR).
The study was authored by a five-person team from Boston College and the University of Maryland at College Park.
Legalization “was associated with modest decreases in cannabis, alcohol, and e-cigarette use.”
To their knowledge, they wrote, “this study is the first to evaluate associations between RCL and RCR policies and adolescent substance use through 2021.”
“Results,” the study concludes, “suggest that legalization and greater control over cannabis markets have not facilitated adolescents’ entry into substance use.”
Over time, it seems adult-use marijuana laws led to lower odds of any cannabis use. “Each additional year of RCL,” the study says, “was associated with 8% higher odds of zero cannabis use (lower likelihood of any use), with non-significant total estimates.”
The opening of retail markets, meanwhile, was associated with 28% higher odds of zero cannabis use,” with each additional year of “RCR exposure” associated with 8 percent higher odds of zero cannabis use.
“Considering other substances, RCL showed a negative total effect estimate for alcohol use,” the study continues, while “no significant results emerged for cigarettes.”
As for vaping, it continues, each additional year of adult-use marijuana legalization laws being in place “was associated with 16% increased odds of zero e-cigarette use, with a negative total effect estimate.” A regulated retail cannabis market, meanwhile, “was associated with 42% increased odds of zero e-cigarette use, with each additional year of RCR associated with 20% increased odds of zero use, both showing significant negative total effect estimates.”
From a youth health perspective, not all of the study’s findings are positive. One outcome associated with the launch of retail stores was that youth who already used marijuana did so more frequently after the market opened.
Specifically, the change was associated with “26% higher frequency of use among users, combining to a nonsignificant total effect estimate” when considered along with the increased likelihood of zero cannabis use. Each additional year of retail markets being open was also associated with “8% higher frequency of use, with a nonsignificant total effect estimate.”
“Using the most recently available 2011 to 2021 data, we found limited associations between RCL and RCR with adolescent substance use, extending previous findings,” the report says.
“RCL was associated with modest decreases in cannabis, alcohol, and e-cigarette use. RCR was associated with lower e-cigarette use, and with lower likelihood but also increased frequency of cannabis use among users, leading to no overall change in cannabis use.”
The team’s report concludes that “given the negative health consequences associated with early and heavy use of these substances, and results suggesting users of cannabis may be increasing their frequency of use in response to retail availability, greater attention is warranted to sources and trajectories among frequent youth users of cannabis.”
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 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 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.”
“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 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.
