A recent study from Washington University in St. Louis sheds light on the complex relationship between adolescent cannabis use and psychosis, suggesting that shared vulnerabilities and self-medication play significant roles in this association.
Published in JAMA Psychiatry, the research provides new insights into how cannabis use and psychosis spectrum symptoms interact, highlighting the need for nuanced approaches to adolescent mental health and substance use prevention.
“Adolescent cannabis use has been consistently posited to contribute to the onset and progression of psychosis,” the researchers wrote in their paper.
Cannabis Use and Psychosis: A Growing Concern
Cannabis is the most commonly used illicit substance among adolescents, with usage rates doubling from 11% to 22% over the past two decades. This rise coincides with a marked decrease in the perceived risk of harm, with only 25% of adolescents now considering weekly cannabis use problematic, down from 36.3%.
This shift in attitudes raises alarms, given the well-documented link between adolescent cannabis use and psychosis. Adolescents who use cannabis are two to four times more likely to develop psychotic disorders, often with earlier onset, more severe symptoms, and higher rates of relapse compared to non-users.
Despite this well-documented association, the exact nature of the relationship between adolescent cannabis use and psychosis has been the subject of ongoing debate. Several hypotheses attempt to explain this connection. The contributing risk hypothesis suggests that cannabis use directly disrupts neurodevelopment during adolescence, increasing the likelihood of psychosis.
The shared vulnerability hypothesis posits that genetic, environmental, or gestational factors predispose individuals to both cannabis use and psychosis, meaning the two phenomena arise from a common underlying cause. Lastly, the self-medication hypothesis proposes that adolescents turn to cannabis to alleviate distress stemming from pre-existing psychotic symptoms.
Diving Further Into Connections Between Cannabis Use and Psychosis
To test these theories, researchers analyzed data from the Adolescent Brain Cognitive Development (ABCD) Study, tracking 11,868 adolescents aged 9 to 10 over four years.
The Adolescent Brain Cognitive Development (ABCD) Study is the largest long-term study of brain development and child health in the United States. Funded by the National Institutes of Health (NIH), it began in 2015 and tracks over 11,800 children recruited at ages 9 to 10, following them into early adulthood. The study collects a wide range of data, including brain imaging, cognitive testing, genetic and biological markers, mental health assessments, and information about lifestyle factors such as sleep, physical activity, and substance use. Its goal is to understand how childhood experiences influence brain development and long-term health outcomes, providing critical insights into adolescent behavior, mental health, and neurodevelopment.
Using data from the ABCD study, the researchers examined psychosis spectrum symptoms before and after cannabis initiation. The findings challenge the contributing risk hypothesis, as cannabis initiation did not consistently lead to an increase in psychosis symptoms. Instead, the data supports the shared vulnerability and self-medication hypotheses.
Adolescents who used cannabis at any point during the study reported more psychosis spectrum symptoms and greater distress compared to their non-using peers, even before they began using cannabis. This aligns with the shared vulnerability hypothesis, indicating a predisposition to both cannabis use and psychosis.
Additionally, researchers observed an increase in psychosis symptoms and associated distress in the period leading up to cannabis initiation, providing evidence that some adolescents may turn to cannabis as a coping mechanism, as suggested by the self-medication hypothesis.
“The findings underscore the importance of accounting for shared vulnerability and self-medication effects when modeling cannabis–psychosis risk associations,” the researchers wrote in their paper.
More Public Health Efforts Needed
These findings highlight the need to address the underlying vulnerabilities that contribute to both psychosis and cannabis use among adolescents. While cannabis use may not directly cause psychosis, its association with increased distress and symptom severity remains a critical concern.
The researchers suggest that public health efforts should aim to educate adolescents about the risks associated with cannabis use, particularly as the perceived harm continues to decline. Early intervention programs should focus on identifying and supporting young people at risk of psychosis or substance use, offering mental health resources to reduce reliance on self-medication.
Kenna Hughes-Castleberry is the Science Communicator at JILA (a world-leading physics research institute) and a science writer at The Debrief. Follow and connect with her on BlueSky or contact her via email at kenna@thedebrief.org