A groundbreaking study by McGill University has found that cannabis use may exacerbate brain changes in young adults at high risk of psychosis. These brain changes, specifically a decrease in synaptic density, may contribute to the social and motivational symptoms that are often difficult to treat with current medications. This discovery opens the door to potential treatments aimed at improving the quality of life for those affected by psychosis, particularly in areas that current therapies fail to address.
Key Findings from McGill University’s Study
The research, published in JAMA Psychiatry, is the first of its kind to show that cannabis use can worsen brain connectivity issues in individuals at risk of psychosis. The study, which involved 49 participants aged 16 to 30, explored the relationship between cannabis use, brain structure, and psychosis risk. Participants included individuals who had experienced recent psychotic symptoms as well as those considered at high risk for developing psychosis.
Decreased Synaptic Density
Synaptic density refers to the number of synapses, or connections between neurons, that allow communication within the brain. The study revealed that participants at risk for psychosis showed significantly lower synaptic density compared to a healthy control group. This finding suggests that individuals at risk for psychosis already experience disruptions in their brain’s ability to communicate effectively, which could contribute to the social withdrawal and lack of motivation commonly seen in psychosis.
Dr. Romina Mizrahi, senior author of the study and professor in McGill’s Department of Psychiatry, explained, “Cannabis appears to disrupt the brain’s natural process of refining and pruning synapses, which is essential for healthy brain development. Our research helps clarify why some individuals are more vulnerable to psychosis after using cannabis.”
The Role of Cannabis in Brain Development
While cannabis is known to increase the risk of developing psychosis—especially in individuals genetically predisposed to the condition—this study is the first to measure real-time structural changes in the brain of a high-risk population. The researchers utilized advanced brain scanning technologies to examine the effects of cannabis on brain connectivity, specifically looking at how it impacts synaptic pruning, a crucial process for brain health.
Implications for Treatment
The study highlights the need for new treatments that go beyond addressing the hallucinations commonly associated with psychosis. Current medications tend to target the more visible symptoms, such as hallucinations, but leave other challenges, like social dysfunction and lack of motivation, untreated. These symptoms can severely affect an individual’s ability to maintain relationships or succeed in work or school environments.
As Dr. Belen Blasco, a PhD student at McGill’s Integrated Program in Neuroscience and first author of the study, noted: “By focusing on synaptic density, we may eventually develop therapies that enhance social function and quality of life for those affected.”
Next Steps in Research
The next phase of research will focus on determining whether the observed brain changes could predict the onset of full-blown psychosis. If so, early detection of these brain alterations could enable earlier intervention, potentially preventing the progression to psychosis and offering better outcomes for at-risk individuals.
This research was conducted at the Douglas Mental Health University Institute and McGill University’s Montreal Neurological Institute-Hospital, with support from the Canadian Institute of Health Research.
