More young people begin recreational cannabis use illegally in states that legalize it

The observational study tracked 6,925 youths and 14,938 adults using data from the Population Assessment of Tobacco and Health in the United States (PATH). Study authors found that young people, ages 12 to 20, were more likely to become cannabis users in states that legalize recreational use than in states that have not legalized the drug. An increased likelihood of use was also documented in adults.

According to a 2020 Natural Survey on Drug Use and Health, 17.9 percent of people aged 12 or older (approximately 49.6 million persons) reported using cannabis in the past 12 months.

Subjects in the study lived in four states that have legalized recreational cannabis use in recent years (California, Massachusetts, Nevada and Maine), 11 states that allow medical cannabis use and 17 states that prohibit all cannabis use.

The authors said using PATH data made the study the first to estimate age-level changes in a nationally representative longitudinal cohort. The study also has a much larger sample size than previous efforts.

"Our findings provide useful information to policymakers and public health practitioners interested in understanding the consequences of legalizing recreational cannabis," said principal investigator Yuyan Shi, PhD, associate professor at the Herbert Wertheim School of Public Health and Human Longevity Science at UC San Diego. "It's especially concerning that increased cannabis use occurs among young people because of the detrimental health effects associated with cannabis use at a young age, including impaired respiratory function, cardiovascular disease and adverse effects on mental health."

Co-authors include: Christian Gunadi, UC San Diego; and Bin Zhu, UC San Diego and Southern University of Science and Technology, China.

Funding for this research came, in part, from the National Institute on Drug Abuse (R01DA042290, R01DA049730).