Cannabis legalization has limited impact on teen use, study shows

Key takeaways:

• Two dozen U.S. states have legalized recreational cannabis, and many allow retail sales of the drug.
• A study showed no significant association with state-level legalization and teen use.

Recent cannabis legalization and retail sales have had a limited impact on teen use, a study showed.

According to research published in JAMA Pediatrics, there has been no net increase in cannabis use in the years during or since 24 U.S. states have legalized recreational use of the drug, and since many of those states have implemented retail sales of it. There also has been no spillover effects on alcohol or tobacco use, researchers reported.

“The changes in policies regarding substance use — in some cases, legalizing access to products such as cannabis, and in other cases making access more restricted, such as flavor restrictions and age restrictions regarding tobacco products — has the potential to change substance access, public views and usage patterns,” Rebekah Levine Coley, PhD, director of the Institute of Early Childhood Policy at Boston College, told Healio.

Coley and colleagues saw the changes in cannabis policies as “an important social force and sought to evaluate how this force was linked to changes in adolescent use of cannabis and other substances,” she said.

For the study, they assessed state cannabis policies and survey responses from high school students from 2011 through 2021 who reported on the frequency of their use of cannabis, alcohol, cigarettes, and e-cigarettes in the prior month.

“Using this combined dataset, we were able to ascertain which students lived in states covered by which substance policies,” Coley said. “We analyzed these data to see if cannabis legalization was associated with different levels of cannabis, alcohol, cigarettes, and e-cigarettes among high school students.”

In all, the study included responses from 898,271 students. Coley and colleagues did not identify an association between recreational cannabis legalization and teens’ likelihood or frequency of cannabis use, although negative total effect estimates indicated significantly lowered use following legalization.

The authors noted that each additional year of legalized cannabis exposure was associated with 8% higher odds of zero cannabis use. The presence of recreational cannabis retail sales was associated with 28% higher odds of zero cannabis use but also 26% higher frequency of use among users, which combined for a nonsignificant effect.

Similarly, each additional year of recreational cannabis sales was associated with 8% higher odds of zero use but also 8% higher frequency of use, also a nonsignificant effect, the researchers said.

Coley said the results fell in line with and “extended prior research, which has sought to assess how changing cannabis policies [is] associated with changing adolescent substance use, finding very limited links.”

“This is surprising to many who thought that legalizing recreational cannabis would increase access and lower potential legal risks, and thus lead to increased use of cannabis,” Coley said. “Indeed, this is the pattern that has been found among adults. However, we did not find this pattern among adolescents. Since adolescents are still not allowed to legally purchase cannabis, legalization might be moving access from illegal and accessible to legal and less accessible sources for adolescents.”

She noted that the findings did not indicate a substantive rise in overall use of other substances following recreational cannabis legalization, but rates of cannabis, alcohol and tobacco use in teenagers remain “concerning.”

“It is important to continue to assess adolescents' substance use access and use and to provide mechanisms to decrease use,” Coley said. “One concerning finding is that although recreational cannabis retail sales in one's state were associated with a lower likelihood of adolescents using any cannabis in the prior month, among those who were users, retail sales were associated with more frequent use. Given that more frequent use carries greater potential risks, this is a pattern that providers should be aware of.”