Summary: A massive study of over 460,000 adolescents has confirmed that even occasional cannabis use during teenage years is a major risk factor for severe mental illness. The research followed participants from age 13 through 26, revealing that those who used cannabis were twice as likely to develop psychotic or bipolar disorders.
With modern THC levels reaching record highs, the study found that these psychiatric conditions typically emerged within two years of initial use, regardless of the teen’s prior mental health history or socioeconomic background.
Key Facts
- Double the Danger: Any self-reported cannabis use between ages 13 and 17 was associated with a 100% increase in the risk of psychotic and bipolar disorders.
- The 2-Year Clock: Psychiatric diagnoses typically followed the first report of cannabis use by an average of 1.7 to 2.3 years.
- Potency Warning: Researchers highlighted that today’s cannabis is far more dangerous than in decades past, with flower exceeding 20% THC and concentrates reaching 95%.
- Scale of Study: The findings are based on a vast dataset of 463,396 individuals followed over a 10-year period.
- Broad Vulnerability: The risk remained significant even when researchers adjusted for other substance use and pre-existing mental health conditions.
Source: Public Health Institute
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.
“The evidence increasingly points to the need for an urgent public health response — one that reduces product potency, prioritizes prevention, limits youth exposure and marketing and treats adolescent cannabis use as a serious health issue, not a benign behavior.”
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.
“This study adds to the growing body of evidence that cannabis use during adolescence could have potentially detrimental, long-term health effects. It’s imperative that parents and their children have accurate, trusted, and evidence-based information about the risks of adolescent cannabis use.”
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.
Key Questions Answered:
A: The study tracked “past-year use.” This means teens who reported using cannabis even occasionally in the previous 12 months showed the same doubled risk as more frequent users.
A: Because the study was longitudinal (tracking the same people over time), researchers confirmed that the cannabis use almost always came first, followed by the diagnosis roughly two years later.
A: THC potency has skyrocketed. The “pot” of the 1990s is nothing like the high-concentrate waxes and vapes of today, which can essentially “overload” a brain that is still building its emotional and cognitive foundations.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this cannabis use and mental health research news
Author: Renate Myles
Source: Public Health Institute
Contact: Renate Myles – Public Health Institute
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Adolescent Cannabis Use and Risk of Psychotic, Bipolar, Depressive, and Anxiety Disorders” by Kelly C. Young-Wolff, Catherine A. Cortez, Stacey E. Alexeeff, Lynn D. Silver, Rosalie Liccardo Pacula, Natalie E. Slama, Alisa A. Padon, Derek D. Satre, Cynthia I. Campbell, Maria T. Koshy, Monique B. Does, and Stacy A. Sterling. JAMA Health Forum
DOI:10.1001/jamahealthforum.2025.6839
Abstract
Adolescent Cannabis Use and Risk of Psychotic, Bipolar, Depressive, and Anxiety Disorders
Importance
As cannabis becomes more accessible and socially accepted, concerns have grown about its potential implications for adolescent mental health. While prior research has linked adolescent cannabis use to psychiatric symptoms, few large, population-based, longitudinal studies have examined associations with clinically diagnosed psychiatric disorders.
Objective
To evaluate whether adolescent cannabis use is associated with an increased risk of incident psychotic, bipolar, depressive, and anxiety disorders during adolescence and young adulthood.
Design, Setting, and Participants This cohort study included adolescents aged 13 to 17 years who were screened for past-year cannabis use at Kaiser Permanente Northern California from 2016 to 2023. Adolescents were followed up through age 25 years or until December 31, 2023. Data were analyzed from February 21, 2024, to August 27, 2025.
Exposure
Time-varying self-reported past-year cannabis use based on universal, confidential screening during standard pediatric care.
Main Outcomes and Measures
Incident clinician-diagnosed psychotic, bipolar, depressive, and anxiety disorders, which were identified through electronic health records using International Classification of Disease codes.
Cox proportional hazards regression models were used to measure the strength of associations between adolescent cannabis use and incident psychiatric diagnoses, with adjustments for sex, race and ethnicity, neighborhood deprivation index, insurance type, and time-varying alcohol and other substance use.
Results
Of 463 396 adolescents (234 114 males [50.5%]; mean [SD] age, 14.5 [1.3] years) included in the sample, 136 708 were Hispanic individuals (29.5%), 93 737 were non-Hispanic Asian individuals (20.2%), 35 346 were non-Hispanic Black individuals (7.6%), 153 102 were non-Hispanic White individuals (33.0%), and 18 795 individuals were multiracial or of other races or ethnicities (4.1%).
At baseline, 26 345 adolescents (5.7%) self-reported past-year cannabis use. Past-year cannabis use was associated with an increased risk of incident psychotic (adjusted hazard ratio [AHR], 2.19; 95% CI, 1.97-2.42), bipolar (AHR, 2.01; 95% CI, 1.82-2.22), depressive (AHR, 1.34; 95% CI, 1.30-1.39), and anxiety disorders (AHR, 1.24; 95% CI, 1.21-1.28). The strength of the associations between cannabis use and incident depressive and anxiety disorders decreased as adolescents aged.
This pattern was similar but slightly attenuated after additional adjustment for past psychiatric conditions (psychotic disorder: AHR, 1.92; 95% CI, 1.73-2.13; bipolar disorder: AHR, 1.73; 95% CI, 1.57-1.90; depressive disorder: AHR, 1.33; 95% CI, 1.29-1.38; anxiety disorder: AHR, 1.19; 95% CI, 1.16-1.23).
Conclusions and Relevance
This cohort study found that adolescent cannabis use was associated with increased risk of incident psychiatric disorders, particularly psychotic and bipolar disorders. These results could inform the development of clinical and educational interventions for parents, adolescents, and clinicians, as well as protective policies to prevent or delay adolescent cannabis use in the context of expanding cannabis legalization.
