As cannabis legalization spreads and the number of consumers continues to grow, more is being revealed about the plant and its effects. So-called cannabis-induced psychosis (CIP) has been making headlines, with healthcare professionals concerned about how weed impacts certain individuals. However, a new study from McGill University in Montreal may reveal who is most at risk.
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“Not every cannabis user will develop psychosis, but for some, the risks are high. Our research helps clarify why,” senior study author Dr. Romina Mizrahi said in a press release.
Mizrahi and fellow researchers analyzed data from 49 participants between the ages of 16 and 30. Some of the participants had experienced recent symptoms of psychosis, while others were considered “high risk.” A control group without signs of psychosis was also included. None of the volunteers were on antipsychotic medication, and the only substance they tested positive for was cannabis.
Scientists reviewed psychiatric and medical screenings as well as brain scans of all the participants. The team honed in on synaptic density (aka the number of connections between neurons and the brain) by looking at levels of a protein called SV2A. When levels are higher, there are more synapses firing; if there’s a depletion, depression can set in.
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The team discovered that participants exhibiting psychotic symptoms tended to have lower synaptic density than the control group. They also found that cannabis can deplete SV2A levels, in line with a similar study released in 2020. Furthermore, researchers discovered cannabis consumption affected a specific region of the brain linked to psychotic episodes.
“Cannabis appears to disrupt the brain’s natural process of refining and pruning synapses, which is essential for healthy brain development,” Mizrahi said.
The study did not necessarily prove that cannabis caused lower synaptic density in psychosis patients, but the correlation between SV2A levels may guide future research. The McGill team hopes the findings will enable physicians to identify those at higher risk of developing psychosis and potentially deploy early intervention strategies. While more research is needed to cement the data, the study is moving the conversation around marijuana and mental health forward
