Consuming cannabis in adolescence doubles the risk of psychotic and bipolar disorders

Science Writing.- Consuming cannabis in adolescence poses a significantly higher risk of developing serious psychiatric disorders in early adulthood, according to a new and extensive study published today in JAMA Health Forum.

The study, based on the follow-up of 463,396 adolescents aged 13 to 17 years old up to 26 years old, found that consuming cannabis in the last year of adolescence doubled the risk of suffering psychotic and bipolar disorders, and increased "significantly" the chances of having depression or anxiety.

Conducted by researchers from Kaiser Permanente, the Public Health Institute, the University of California, San Francisco, and the University of Southern California, the study analyzed data from electronic health records of routine pediatric visits between 2016 and 2023.

On average, adolescents who had consumed cannabis were diagnosed with some psychiatric disorder between 1.7 and 2.3 years later.

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The authors point out that the longitudinal design of the study reinforces the evidence that exposure to cannabis in adolescence is a potential risk factor for the development of mental illnesses.

«As cannabis becomes more potent and is marketed more aggressively, this study shows that its use in adolescents is associated with twice the risk of psychotic and bipolar disorders, two of the most serious mental health conditions», warns Lynn Silver, director of the Getting it Right from the Start program at the Public Health Institute and co-author of the study.

A very popular drug

Cannabis is the most used illegal drug by American teenagers. According to the 'Monitoring the Future' study, consumption increases with the school level (from 8% in 8th grade, i.e., with 13-14 years old, to 26% in 12th grade, when they are 17-18 years old). According to the 2024 National Survey on Drug Use and Health, more than 10% of adolescents aged 12 to 17 have used in the last year. To compound the situation, average THC levels in California cannabis flower now exceed 20%, much more than in previous decades, and concentrates can surpass 95% THC. Unlike other research, this study examined any cannabis use reported in the last year through universal testing of adolescents during standard pediatric care, rather than focusing solely on heavy use or cannabis use disorder. "Even after taking into account pre-existing mental health conditions and the use of other substances, adolescents who reported using cannabis had a substantially higher risk of developing psychiatric disorders," warns the study's lead author, Kelly Young-Wolff. You can also read: "It is imperative that parents and their children have accurate and evidence-based information about the risks," he emphasizes. Furthermore, the study found that consumption was more common among adolescents enrolled in Medicaid and those living in neighborhoods with greater socioeconomic deprivation, meaning that this drug could exacerbate existing mental health disparities.