Cannabis Worsens Brain Connectivity Deficits in Psychosis Risk

Young adults at risk of psychosis show reduced synaptic density, a critical brain connectivity deficit that cannabis use appears to exacerbate, according to new research. 

The study revealed lower synaptic density linked to social withdrawal and motivational deficits, symptoms poorly addressed by current medications. Researchers found that cannabis disrupts synaptic pruning, an essential brain development process.

Using advanced brain scanning, the study marks the first real-time measurement of brain structural changes in high-risk individuals, offering insights into psychosis progression. These findings could pave the way for therapies targeting social and functional deficits in psychosis. Next steps include investigating whether these brain changes can predict psychosis development for earlier intervention.

Key Facts:

• Cannabis use disrupts synaptic pruning in young adults at risk of psychosis.
• Lower synaptic density is linked to social withdrawal and motivational deficits.
• This is the first real-time measurement of brain structural changes in high-risk populations.

Source: McGill University

Young adults at risk of psychosis show reduced brain connectivity, a deficit that cannabis use appears to worsen, a new study has found. The breakthrough paves the way for psychosis treatments targeting symptoms that current medications miss.

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

“Not every cannabis user will develop psychosis, but for some, the risks are high. Our research helps clarify why,” said Dr. Romina Mizrahi, senior author of the study and professor in McGill’s Department of Psychiatry.

“Cannabis appears to disrupt the brain’s natural process of refining and pruning synapses, which is essential for healthy brain development.”

Hope for new treatments

Using advanced brain scanning technology, the team studied 49 participants aged 16 to 30, including individuals with recent psychotic symptoms and those considered at high risk.

The results, published in JAMA Psychiatry, indicate that lower synaptic density is linked to social withdrawal and lack of motivation, symptoms the researchers say are difficult to treat.

“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 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.”