People with cannabis use disorder (CUD) have higher dopamine levels in an area of the brain linked to psychosis, found a new study published in JAMA Psychiatry.
The findings may help explain why cannabis use increases the risk of key symptoms of schizophrenia and other psychotic disorders like hallucinations and delusions, said first author of the study, Jessica Ahrens, a PhD student at McGill University, in a press release.
Excess dopamine has been linked to the psychotic symptoms of schizophrenia. While cannabis use is consistently linked with a higher risk of psychosis and is known to influence dopamine, the mechanism linking it to psychosis remains unknown.
In the current study, researchers investigated whether a common alteration in the dopamine system is involved in both CUD and psychosis and if it can be observed in those with CUD whether or not they have been diagnosed with first-episode schizophrenia.
To do so, they recruited 61 individuals between 2019 and 2023 from an early psychosis service in Ontario, Canada. The sample included those with and without CUD, with some in each group having been diagnosed with first-episode schizophrenia. Dopamine activity was assessed via neuromelanin-sensitive MRI.
Ultimately, the researchers found that participants with CUD had an abnormally high neuromelanin signal in a subregion of the brain linked to untreated psychotic symptoms. Severity was linked to cannabis use.
“The lack of clear biological evidence linking cannabis to psychosis has made it harder to persuade young people with psychotic symptoms to reduce their use,” Dr. Lena Palaniyappan, Professor of Psychiatry at McGill and Psychiatrist at the Douglas Mental Health University Institute, said in a press release.
“Our findings could help doctors and mental health professionals better educate patients about the potential risks of frequent cannabis use, especially for those with a family history of psychosis,” he added.
Sources: EurekAlert, JAMA Psychiatry
