Adolescent cannabis use and psychosis: Study finds shared risk factors and self-medication patterns

A recent study published in JAMA Psychiatry sheds light on the relationship between adolescent cannabis use and psychosis spectrum symptoms. Researchers found that adolescents who used cannabis during the study period reported more psychosis spectrum symptoms and greater distress from these symptoms compared to those who never used cannabis. The findings suggest a shared vulnerability between cannabis use and psychosis risk, while also providing support for the idea that some individuals may use cannabis to self-medicate.

Cannabis is the most commonly used illicit substance among adolescents, with its use increasing over the past two decades alongside a decline in perceived risk. Early cannabis initiation has been associated with an increased risk of psychotic disorders, more severe symptoms, and earlier symptom onset. Despite this, the exact nature of the relationship between cannabis use and psychosis remains unclear.

Does cannabis use disrupt brain development, leading to psychosis? Or do shared genetic or environmental factors make some individuals vulnerable to both cannabis use and psychosis? Alternatively, could individuals experiencing distress from psychosis symptoms turn to cannabis as a form of self-medication?

To address these questions, researchers conducted a longitudinal study focusing on childhood and early adolescence, a critical developmental period often linked to heightened vulnerability to cannabis and psychosis interactions.

“Cannabis is the most frequently used illicit substance among adolescents. As time goes on, adolescents are using cannabis more and their perceptions of its potential harm are decreasing,” said study author K. Juston Osborne, a postdoctoral research scholar at Washington University in St. Louis.

Free daily newsletter

“Adolescence is also a vulnerable developmental period that sets the stage for later psychosis risk. Approximately 1% of the population will be diagnosed with a psychotic disorder with typical onset in late adolescence or early adulthood. Considering evidence suggests that starting to use cannabis in early adolescence is a particularly potent risk factor for psychosis, it is critical to understand the nature of the relationship between cannabis use and psychosis risk.”

The researchers used data from the Adolescent Brain Cognitive Development (ABCD) study, a large-scale longitudinal study involving 11,868 children from across the United States. Participants were followed over five waves of data collection, with psychosis spectrum symptoms and cannabis use assessed at multiple time points. Psychosis spectrum symptoms—such as unusual thoughts, perceptual disturbances, and social withdrawal—were measured using a validated questionnaire designed for children. Cannabis initiation was defined as the first reported use of the substance.

The study’s findings support both the shared vulnerability and self-medication hypotheses. Adolescents who used cannabis at any point during the study reported more psychosis spectrum symptoms and greater symptom distress than those who never used cannabis. This finding aligns with the shared vulnerability hypothesis, suggesting that adolescents who are predisposed to psychosis may also be more likely to use cannabis.

Consistent with the self-medication hypothesis, psychosis spectrum symptoms and distress increased in the period leading up to cannabis initiation. This suggests that some adolescents may turn to cannabis in an attempt to cope with emerging symptoms. After cannabis initiation, there was no significant increase in the number of psychosis spectrum symptoms, although distress levels temporarily decreased. These findings indicate that while cannabis may provide short-term relief, it is unlikely to be an effective long-term solution for managing psychosis symptoms.

“This research suggests a complex interplay between starting to use cannabis in early adolescence and psychosis risk,” Osborne told PsyPost. “Some adolescents have risk factors that make them more vulnerable to using cannabis and more vulnerable to experiencing symptoms associated with psychosis. In response to these symptoms, adolescents may turn to cannabis in an attempt to alleviate distress.”

In contrast, the study found limited evidence supporting the hypothesis that cannabis use directly contributes to psychosis symptoms during early adolescence. While previous research has demonstrated a dose-dependent relationship between cannabis use and psychosis risk, the current study focused on the early stages of use, when high-frequency or high-potency use is less common. As a result, the potential for cannabis to disrupt brain development and contribute to psychosis may not have been fully captured.

“Research from past studies suggests that using cannabis may put adolescents at even greater risk for experiencing more symptoms and for developing a psychotic disorder,” Osborne explained. “Considering the strong evidence for a putative causal effect of cannabis on psychosis spectrum symptoms, we were anticipating that we would observe support for cannabis use initiation being associated with future increases in psychosis spectrum symptoms.”

“However, our focus on cannabis use initiation rather than use metrics, such as quantity and frequency of use, may have contributed to the lack of associations in that direction observed in the current study. It’s important to continue studying these relationships to inform intervention efforts to reduce adolescent substance use and to prevent psychosis.”

Future research should continue to follow adolescents as they progress into later developmental stages, where the frequency and intensity of cannabis use often increase. This could provide a clearer picture of how cannabis use impacts psychosis risk over time.

“Ultimately, we would like to unpack the nature of the relationship between cannabis use and psychosis risk,” Osborne said. “This would both inform our understanding of the pathophysiology of psychosis, as well as help identify if and for whom cannabis use may increase psychosis risk.”

“In an ideal world, we may hope that children would not use cannabis, particularly while their brains are still maturing,” he added. “However, cannabis use is common in adolescence and children are often more concerned with fitting in than weighing their actions against potential distant health outcomes.”

“In regard to psychosis risk, it is important for parents to know that the vast majority of adolescents that use cannabis will not go on to develop a psychotic disorder and, consistent with the findings from our paper, these are complex relationships that we are still trying to understand. However, parents should educate themselves on early signs that their teenager may be at risk for psychosis and have a serious conversation with their teenager about abstaining from cannabis in the event these signs emerge.”

The study, “Psychosis Spectrum Symptoms Before and After Adolescent Cannabis Use Initiation,” was authored by K. Juston Osborne, Deanna M. Barch, Joshua J. Jackson, and Nicole R. Karcher.