A new study has revealed concerning effects of cannabis on the brain, particularly for individuals at risk of psychosis. Conducted by researchers at McGill University, the study found that marijuana use may reduce brain connectivity by disrupting synaptic density—the connections between neurons that allow the brain to communicate. This disruption could contribute to social withdrawal, lack of motivation, and other cognitive issues.
Using advanced brain scanning technology, scientists examined 49 participants aged 16 to 30, including those with recent psychotic symptoms and individuals considered high-risk. The results showed that cannabis use appeared to interfere with the brain’s natural process of refining and pruning synapses, which is crucial for healthy development. Researchers suggest this could explain why some users experience negative psychological effects.
Dr. Romina Mizrahi, senior author of the study, emphasized that while not every cannabis user will develop psychosis, the risks are significant for certain individuals. The findings may also help develop treatments targeting synaptic density, potentially improving therapies for psychotic disorders. First author Belen Blasco noted that current medications primarily address hallucinations but do little to improve social functioning—something this research could help change.
The study is the first to measure structural changes in high-risk individuals’ brains in real time, making it a groundbreaking step in understanding cannabis-related mental health risks. Moving forward, researchers plan to investigate whether these brain changes could predict psychosis development, opening the door for earlier interventions and better treatment strategies.
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