A recent study has revealed that frequent cannabis use is associated with increased dopamine levels in the brain, which could lead to psychosis. Conducted by Canadian researchers, the study highlights the long-term health effects of cannabis, six years after its legalization in Canada. The findings were published in JAMA Psychiatry and underscore a significant concern regarding cannabis use and its potential psychiatric risks.
Using advanced neuromelanin-sensitive magnetic resonance imaging (MRI), researchers observed heightened dopamine activity in individuals with cannabis use disorder (CUD). The increased dopamine was found in brain regions previously connected to hallucinations and delusions, which are common symptoms of psychotic disorders. This represents a crucial step in understanding the biological links between cannabis consumption and mental health issues.
The research included 61 participants aged 18 to 35 from London, Ontario. Among them were individuals with CUD, those experiencing early psychosis, and healthy controls. The study revealed that participants with CUD exhibited elevated neuromelanin signals in a specific midbrain area associated with psychosis. Notably, these elevated signals persisted even after one year, indicating that changes in dopamine levels due to cannabis use may have lasting effects.
Lena Palaniyappan, a professor at McGill University and the study’s senior author, noted that the darker regions observed in the brains of heavy cannabis users suggest abnormal dopamine levels, similar to those found in individuals a decade older. The researchers confirmed that the severity of cannabis use correlated with the intensity of these signals, emphasizing the importance of understanding dosage and frequency in cannabis consumption.
The implications of this study are significant, as it provides clear evidence connecting cannabis use to dopamine alterations and psychosis, a link that has been debated in the past. Previous imaging studies using PET scans produced inconsistent results, but neuromelanin-MRI offers a comprehensive view of dopamine activity over time, rather than just immediate effects.
Palaniyappan expressed the urgency for clinicians, patients, and families to collaborate in addressing the risks associated with cannabis use. The findings highlight a critical need for further research into the long-term impacts of cannabis on mental health.
