Adolescents who use cannabis and report symptoms of psychosis may be self-medicating to alleviate those symptoms and the associated distress, according to the results of a new study.
In the study, published in the journal JAMA Psychiatry, researchers analysed data from the Adolescent Brain Cognitive Development Study, a large longitudinal study of child and adolescent brain development, with a cohort of nearly 12,000 children starting at an average age of 9.5 years.
Researchers analysed data to understand exactly how cannabis use and psychosis in adolescents are linked. Three hypotheses were tested: The contributing risk hypothesis suggests cannabis use in adolescents is a contributing cause of symptoms of psychosis by disrupting brain development; The shared vulnerability hypothesis suggests cannabis use and the development of psychosis are jointly linked through environmental or other factors; The self-medication hypothesis suggests young people are more likely to turn to cannabis after experiencing symptoms of psychosis as a means of self-medication.
The contributing risk hypothesis is most commonly cited as being the biggest risk factor in cannabis, suggesting that where cannabis is more freely available more adolescents will go on to consume it and then develop psychosis. However, researchers found that the data did not support this link “as psychosis spectrum symptoms generally did not increase after cannabis initiation”.
The data did show that there was an increase in the number of psychosis spectrum symptoms in adolescents before cannabis use started, aligning with the self-medication hypothesis. Adolescents who used cannabis at any point during the study period reported a greater number of psychosis spectrum symptoms and more distress compared to those who never used cannabis, which lends support to the shared vulnerability hypothesis.
The results suggest that the links between teen cannabis use and psychosis are more complex than simply being cause and effect, and that teens at greater risk of developing psychosis may then go on to use cannabis to treat the symptoms they experience. “Shared risk vulnerabilities and attempts to self-medicate symptom-related distress may lead to initial cannabis initiation in adolescence,” the study authors said. “Whereas subsequent increases in the frequency and quantity of cannabis use throughout adolescent development may then contribute to psychosis onset in young adulthood.”
