Study: Adolescent Cannabis Use Linked to Doubling Risk of Psychotic and Bipolar Disorders

Oakland, CA (February 20, 2026)—Adolescents who use cannabis could face a significantly higher risk of developing serious psychiatric disorders by young adulthood, according to a large new study published today in JAMA Health Forum. The longitudinal study followed 463,396 adolescents ages 13 to 17 through age 26 and found that past-year cannabis use during adolescence was associated with a significantly higher risk of incident psychotic (doubled), bipolar (doubled), depressive and anxiety disorders. The study was conducted by researchers from Kaiser Permanente, the Public Health Institute’s Getting it Right from the Start, the University of California, San Francisco and the University of Southern California, and was funded by a grant from NIH’s National Institute on Drug Abuse (R01DA0531920).

The study analyzed electronic health record data from routine pediatric visits between 2016 and 2023. Cannabis use preceded psychiatric diagnoses by an average of 1.7 to 2.3 years. The study’s longitudinal design strengthens evidence that adolescent cannabis exposure is a potential risk factor for developing mental illness.

“As cannabis becomes more potent and aggressively marketed, this study indicates that adolescent cannabis use is associated with double the risk of incident psychotic and bipolar disorders, two of the most serious mental health conditions,” said Lynn Silver, M.D., program director of the Getting it Right from the Start, a program of the Public Health Institute, and a study co-author.

Cannabis is the most used illicit drug among U.S. adolescents. The Monitoring the Future study shows use rising with grade level — from about 8% in 8th grade to 26% in 12th grade — and according to the 2024 National Survey on Drug Use and Health, more than 10% of all U.S. teens aged 12 to 17 report past-year use. At the same time, average THC levels in California cannabis flower now exceed 20%, far higher than in previous decades, and concentrates can exceed 95% THC.

Unlike many prior studies, the research examined any self-reported past-year cannabis use, with universal screening of teens during standard pediatric care, rather than focusing only on heavy use or cannabis use disorder.

“Even after accounting for prior mental health conditions and other substance use, adolescents who reported cannabis use had a substantially higher risk of developing psychiatric disorders — particularly psychotic and bipolar disorders,” said Kelly Young-Wolff, Ph.D., lead author of the study and senior research scientist at the Kaiser Permanente Division of Research.

The study also found that cannabis use was more common among adolescents enrolled in Medicaid and those living in more socioeconomically deprived neighborhoods, raising concerns that expanding cannabis commercialization could exacerbate existing mental health disparities.

###

The Public Health Institute is an independent nonprofit organization that advances wellbeing and health equity with communities around the world. PHI develops research, leadership and partnerships to build strong public health policy, programs, systems and practices. For more information, visit www.phi.org.