Cannabis operate is associated with brain changes in youthful adults at risk of psychosis

A fresh study has found that youthful adults at risk for psychosis show reduced brain connectivity, and this deficit appears to be getting worse. The breakthrough paves the way for treatments for psychosis that target symptoms missed by current medications.

In the first study of its kind, researchers from McGill University detected a marked decrease in synaptic density – the connections between neurons that enable brain communication – in people at risk of psychosis compared to a hearty control group.

Not every cannabis user will develop psychosis, but for some the risk is high. Our research helps explain why. Cannabis appears to interfere with the brain’s natural process of clearing and pruning synapses, which is imperative for hearty brain development.

Dr. Romina Mizrahi, senior author of the study and professor in the Department of Psychiatry at McGill

Hope for fresh treatment methods

Using advanced brain scanning technology, the team examined 49 participants aged 16 to 30, including those with recent psychotic symptoms and those at high risk. Results published in JAMA Psychiatry, indicate that lower synaptic density is associated with social withdrawal and lack of motivation, and these symptoms are complex to treat, according to researchers.

“Current medications largely treat hallucinations but do not alleviate symptoms that make it complex to cope with social relationships, work or school,” said first author Belen Blasco, a doctoral student in McGill’s Integrated Neuroscience Program. “By focusing on synaptic density, we can ultimately develop therapies that improve social function and quality of life for people affected by this disease.”

Although cannabis is a known risk factor for developing psychosis, which can lead to schizophrenia, this is the first time scientists have measured structural changes in the brains of high-risk populations in real time.

In the next phase of the study, the team will investigate whether the observed brain changes can predict the development of psychosis, potentially enabling earlier intervention.

The study was conducted at the Institute of the University of Mental Health. Douglas and at the Hospital of the Neurological Institute of McGill University in Montreal. The project was supported by the Canadian Institutes of Health Research.