Study Links Teen Cannabis Use to Higher Risk of Mental Health Disorders
A large Kaiser Permanente study of 463,396 adolescents found those using cannabis were twice as likely to develop psychotic or bipolar disorders, with elevated risks for depression and anxiety. The research suggests adolescence is a vulnerable period for cannabis-related mental health harms, though causality remains complex.
A Kaiser Permanente analysis of nearly half a million adolescents finds that those who report using cannabis in the past year are more likely to later receive a diagnosis of psychotic, bipolar, depressive, or anxiety disorders. The study, published in JAMA Health Forum, found that self-report of past-year cannabis use typically occurred an average of 1.7 to 2.3 years before a psychiatric diagnosis, though the research could not definitively determine whether cannabis use causes psychiatric disorders or whether teens use cannabis to address emerging mental health symptoms.
The analysis included 463,396 adolescents of diverse racial and ethnic backgrounds in Northern California, with 5.7% reporting using cannabis the previous year. The researchers tracked health data for the patients through age 25, or until the end of 2023, and found the teens who reported cannabis use were more than twice as likely to be later diagnosed with a psychotic disorder or bipolar disorder, 34% more likely to be diagnosed with depression, and 24% more likely to be diagnosed with anxiety disorders.
The strength of the associations between cannabis use and depressive and anxiety disorders decreased as adolescents aged and were no longer statistically significant among young adults aged 21-25. In contrast, elevated risks for psychotic and bipolar disorders persisted into young adulthood, suggesting adolescence is a particularly vulnerable time for cannabis-related mental health problems.
The authors emphasized that cannabis products available today often contain high concentrations of tetrahydrocannabinol (THC), which may disrupt the endocannabinoid system and affect brain regions involved in motivation, emotional regulation, and cognition. They noted that cannabis has not been shown to be an effective treatment for depression or anxiety and that ongoing use is associated with worsening mood symptoms and poorer adherence to mental health treatment.
The results highlight the importance of early prevention, routine screening for cannabis use in pediatric care, clear public health messaging about risks, and policies that limit youth access and exposure to cannabis, particularly as legalization expands. The study was funded by the National Institute on Drug Abuse.