A large new study suggests that teenagers who use cannabis may be more likely to develop serious mental health conditions in early adulthood, including psychotic disorders and bipolar disorder. The findings add to growing evidence that cannabis use during adolescence could have lasting effects on mental health.
Researchers followed more than 463,000 adolescents aged 13 to 17 until they reached the age of 26. The study, published in JAMA Health Forum, found that teenagers who reported using cannabis within the previous year were significantly more likely to later develop psychotic disorders, bipolar disorder, depression, and anxiety.
The strongest associations were seen for psychotic and bipolar disorders, with the risk of both conditions approximately doubling among young people who had used cannabis.
Importantly, cannabis use was typically reported between 1.7 and 2.3 years before a psychiatric diagnosis, strengthening the evidence that cannabis exposure during adolescence may contribute to the later development of mental illness.
Looking beyond heavy cannabis use
Unlike many previous studies, the researchers did not focus solely on heavy cannabis use or cannabis use disorder. Instead, they examined any self-reported cannabis use during the previous year, using information collected through routine screening during paediatric healthcare visits.
Lead author Dr Kelly Young-Wolff said: “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.”
She added:
“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.”