“Not every cannabis user will develop psychosis, but for some, the risks are high. Our research helps clarify why,” said senior author of the study, Dr. Romina Mizrahi, professor at the Department of Psychiatry at McGill University, in a press release.
For the study, researchers recruited 49 participants aged between 16 and 30 years old. Participants included individuals with recent psychotic symptoms, those considered at high risk, and healthy controls. Synaptic density was assessed via 90-minute PET scans across various brain regions. Meanwhile, cannabis use was confirmed by urine drug tests, and gray matter microstructured was assessed via diffusion-weighted MRI to estimate neurite density.
Ultimately, the researchers detected a significant decrease in synaptic density among individuals with early psychosis and those at risk of psychosis compared to healthy controls. Lower synaptic density was linked to difficult-to-treat symptoms such as social withdrawal and lack of motivation. The researchers further found that synaptic density was lower in cannabis users.
“Cannabis appears to disrupt the brain’s natural process of refining and pruning synapses, which is essential for healthy brain development,” said Mizrahi.
The study marks the first time researchers have assessed brain structural changes in a high-risk population in real-time.
“Current medications largely target hallucinations, but they don’t address symptoms that make it difficult to manage social relationships, work, or school,” said first author of the study, Belen Blasco, a PhD student at McGill’s Integrated Program in Neuroscience, “By focusing on synaptic density, we may eventually develop therapies that enhance social function and quality of life for those affected.”
The researchers next hope to explore whether the observed changes could predict the development of psychosis and thereby enable earlier treatment.
Sources: EurekAlert, JAMA Psychiatry