Adolescent Cannabis Use Linked to Increased Risk of Psychotic and Bipolar Disorders

What's new

A recent study published in JAMA Health Forum indicates that adolescents who use cannabis may face a substantially increased risk of developing serious mental health conditions, such as psychotic and bipolar disorders, by young adulthood [1]. The research, which tracked over 463,000 adolescents, found that those who reported cannabis use within the past year had a significantly higher likelihood of subsequently being diagnosed with psychotic disorders, bipolar disorder, depression, and anxiety. Specifically, the risk of both psychotic and bipolar disorders was approximately doubled among adolescent cannabis users [1].

This study is notable for its large sample size and its longitudinal design, which allowed researchers to observe cannabis use preceding mental health diagnoses by an average of 1.7 to 2.3 years. Unlike many previous studies that focused primarily on heavy cannabis use, this research examined any self-reported cannabis use, providing a broader understanding of potential risks [1]. The findings highlight concerns among public health experts about the long-term effects of cannabis on developing brains, especially given the increasing potency of cannabis products and their continued prevalence among teenagers.

The science behind it

The study utilized electronic health record data collected during routine pediatric visits from 2016 through 2023, following participants from ages 13-17 through age 26 [1]. This methodology allowed researchers to establish a temporal relationship, showing that cannabis use often occurred before the onset of mental health conditions. By tracking such a large cohort over several years, the study provides robust evidence for an association between adolescent cannabis use and later mental illness.

Researchers controlled for confounding factors such as pre-existing mental health conditions and other substance use, strengthening the conclusion that adolescent cannabis use itself is linked to the increased risk [1]. The study's authors emphasize that the developing adolescent brain may be particularly vulnerable to the effects of cannabis, especially with the rising tetrahydrocannabinol (THC) levels in modern cannabis products. Some cannabis concentrates, for instance, can contain over 95% THC, a significant increase from past decades [1]. This increased potency may contribute to the observed heightened risks for mental health disorders.

What it means in practice

The findings suggest important implications for public health and parental guidance. Given the observed association, there is a call for an urgent public health response that includes reducing product potency, prioritizing prevention efforts, limiting youth exposure and marketing, and treating adolescent cannabis use as a serious health issue rather than a benign behavior [1]. Parents and guardians are encouraged to have accurate, evidence-based information about the potential risks of adolescent cannabis use to inform their children.

Furthermore, the study revealed that cannabis use was more common among adolescents enrolled in Medicaid and those living in socioeconomically disadvantaged neighborhoods [1]. This raises concerns that the expanding commercialization of cannabis could exacerbate existing disparities in mental health outcomes, highlighting the need for targeted public health interventions in vulnerable communities.

Caveats

While the study provides strong evidence for an association, it is important to note that observational studies, even large-scale longitudinal ones, cannot definitively prove causation. Other unmeasured factors or genetic predispositions could potentially contribute to both cannabis use and mental health conditions. However, the temporal relationship observed, where cannabis use preceded diagnoses, and the control for various confounding factors, lend significant weight to the findings [1]. The study relied on self-reported cannabis use, which might be subject to underreporting, though universal screening in routine pediatric care likely mitigated this to some extent. Future research, including randomized controlled trials where ethically feasible, could further elucidate the causal mechanisms at play.

Source: [1] https://www.sciencedaily.com/releases/2026/06/260622091515.htm