Federally Funded Study Shows Marijuana Legalization Is Not Associated With Increased Teen Use

A new study funded by a top federal drug agency has found that state-level marijuana legalization is not associated with increased youth cannabis use.

The research article, published in the American Journal of Preventive Medicine this month, looked at data from three longitudinal studies on past-year cannabis consumption and frequency of use among adolescents from 1999 to 2020 in Oregon, New York and Washington State.

Washington voters legalized marijuana in 2012, followed by those in Oregon in 2014. New York moved to enact legalization last year, but retail stores haven’t opened yet, with regulators saying that will likely start happening before the end of this year.

With marijuana legalization on the ballot in five states across the U.S. this month, opponents have repeatedly made the argument that the reform would lead more underage people to use cannabis, despite numerous studies contradicting that point.

Now another study has similarly debunked the argument, with researchers at the University of Washington, Colorado State University and Oregon Social Learning Center finding that the “change in legalization status across adolescence was not significantly related to within-person change in the probability or frequency of self-reported past-year cannabis use.”

The study, which received funding from the National Institute on Drug Abuse (NIDA), showed 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.”

“Taken together with previous studies, these findings add weight to the conclusion that adolescent cannabis use is holding steady in the wake of legalization, at least in the years relatively proximate to the policy change,” the research article says. “This analyses expand on previous findings by specifically parsing variance in adolescent cannabis use owing to age, sex, birth cohort (i.e., population-level trends in use), and legalization.”

“Findings are not consistent with changes in the prevalence or frequency of adolescent cannabis use after legalization.”

This builds on an already sizable body of scientific literature that’s similarly determined that creating regulated cannabis markets for adults either has a neutral effect on underage use, or is even associated with declines in the behavior.

For example, another federally funded study from Michigan State University researchers that was published in the journal PLOS One this summer 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.”

Meanwhile, adolescent marijuana use in Colorado declined significantly in 2021, according to the latest version of a biennial state survey released in June.

“When we do look at our study along with the other studies that have asked similar questions, the pattern of results so far is encouraging,” University of Washington’s Jennifer Bailey, author of the new NIDA-funded study, told Marijuana Moment. “That is, most studies are not showing increases in teen cannabis use following legalization of cannabis for adults.”

She cautioned, however, that “we need to keep monitoring teen cannabis use in the wake of legalization.”

“Although things look encouraging now, as we note in our paper, alcohol use increased slowly over 40 years after the end of alcohol prohibition,” she said. “So, it may take more time for us to see any effects of legalization on teen cannabis use. Hopefully, trends will continue as they are going now.”

Advocates have long argued that providing regulated access to marijuana at stores where there are requirements to check ID, for example, would mitigate the risk of adolescent consumption.

A recent study out of California found that “there was 100 percent compliance with the ID policy to keep underage patrons from purchasing marijuana directly from licensed outlets.”

The Coalition for Cannabis Policy, Education, and Regulation (CPEAR), an alcohol and tobacco industry-backed marijuana policy group, also released a report this year analyzing data on youth marijuana use rates amid the state-level legalization movement.

One of the most recent federally funded surveys on the topic stressed that youth marijuana use “decreased significantly” in 2021, as did teen consumption of illicit substances overall.

The 2020 federally funded Monitoring the Future survey further found that cannabis consumption among adolescents “did not significantly change in any of the three grades for lifetime use, past 12-month use, past 30-day use, and daily use from 2019-2020.”

Another federally funded study, the National Survey on Drug Use and Health (NSDUH), was released in October showing that youth marijuana use dropped in 2020 amid the coronavirus pandemic and as more states moved to enact legalization.

Further, an analysis published by the Journal of the American Medical Association last year found that enacting legalization has an overall impact on adolescent cannabis consumption that is “statistically indistinguishable from zero.”

The U.S. Department of Education’s National Center for Education Statistics also analyzed youth surveys of high school students from 2009 to 2019 and concluded that there’s been “no measurable difference” in the percentage of those in grades 9-12 who reported consuming cannabis at least once in the past 30 days.

In a separate, earlier analysis, the Centers for Disease Control and Prevention found that marijuana consumption among high school students declined during the peak years of state-legal recreational cannabis legalization.

There was “no change” in the rate of current cannabis use among high school students from 2009-2019, the survey found. When analyzed using a quadratic change model, however, lifetime marijuana consumption decreased during that period.

Another study released by Colorado officials in 2020 showed that youth cannabis consumption in the state “has not significantly changed since legalization” in 2012, though methods of consumption are diversifying.

An official with the White House Office of National Drug Control Policy’s National Marijuana Initiative went even further in 2020, admitting that, for reasons that are unclear, youth consumption of cannabis “is going down” in Colorado and other legalized states and that it’s “a good thing” even if “we don’t understand why.”