New Research Shows Cannabis Use Disorder Linked to Psychosis and Brain Changes

Study reveals increased dopamine levels in brain regions associated with psychosis among cannabis users, raising concerns over mental health risks.

Elevated Dopamine Levels in Brain Regions Tied to Psychosis Found in Cannabis Users

A new study sheds light on how cannabis use disorder (CUD) leads to changes in the brain that are linked to psychosis, providing a crucial insight into the mental health risks associated with cannabis use.

In a study published on April 9, 2025, in JAMA Psychiatry, researchers from London Health Sciences Centre Research Institute (LHSCRI) and Western University’s Schulich School of Medicine & Dentistry found that cannabis users exhibited heightened dopamine activity in brain regions associated with psychosis. These findings suggest that cannabis use may accelerate dopamine-related brain aging and increase the risk of psychosis, especially in vulnerable individuals.

Brain Imaging Technique Reveals Significant Dopamine Activity in Cannabis Users

Using a non-invasive imaging method known as neuromelanin-sensitive MRI, researchers observed darker spots in brain scans of cannabis users. These spots indicate excess dopamine activity in areas of the brain linked to psychosis, namely the substantia nigra and ventral tegmental areas. The findings are a significant step forward in understanding the biological effects of cannabis on the brain and its potential role in psychosis.

Neuromelanin, a black pigment in the brain, accumulates in areas with high dopamine levels. The research found that cannabis users had more pronounced neuromelanin buildup, with some exhibiting levels typically seen in individuals 10 years older than their actual age. This excess dopamine could contribute to disrupted brain processes and increase the risk of psychotic episodes.

Link Between Cannabis Use and Psychosis May Explain Rising Cases Since Legalization

The study builds on prior evidence suggesting that the legalization of cannabis in Canada has coincided with an uptick in cannabis-induced psychosis. Emergency departments across Canada have reported more cases of psychosis following cannabis use since its legalization in 2018. Lena Palaniyappan, senior author of the study, emphasized that this new research provides a “straight line” linking cannabis use, dopamine, and psychosis—a connection that had never been conclusively shown before.

Palaniyappan, who is also an adjunct professor at McGill University, expressed concern over the increasing number of adolescents experiencing cannabis-induced psychosis. “We’re seeing adolescents who have two or three brief episodes of psychosis after using cannabis, followed by a much more significant episode,” she said. “These findings underscore the importance of early intervention and education about the risks of cannabis use.”

Understanding the Dopamine System and Its Role in Psychosis

Dopamine is a critical neurotransmitter that plays a key role in mood regulation, learning, motivation, and motor control. Excessive dopamine levels can cause disruptions in these processes, contributing to symptoms of psychosis, particularly in individuals who are already at risk.

The study found that cannabis use disorder leads to a spike in dopamine levels in the brain, particularly in the areas that control emotions and perceptions, such as the midbrain. While dopamine is essential for normal brain function, its overproduction can overwhelm the brain’s natural processes, leading to psychotic episodes. Betsy Schaefer, co-author of the study, noted that this dopamine disruption is especially concerning for individuals who may already have underlying vulnerabilities.

Implications of the Study: Raising Public Awareness About Cannabis Use and Mental Health Risks

The study’s findings underscore the urgent need for public health campaigns that raise awareness about the mental health risks associated with cannabis use. As cannabis becomes more widely used following legalization, it is crucial for clinicians, patients, and families to understand the potential mental health implications.

Dr. Julie Richard, a psychiatrist and physician lead of LHSCRI’s Prevention and Early Intervention Program for Psychosis (PEPP), highlighted the importance of addressing these risks with patients, especially adolescents who may be more susceptible to the effects of cannabis. “We need to educate young people about the dangers of using cannabis and how it can push their brains toward psychosis,” Richard said.

Jessica Ahrens, a PhD candidate at McGill University and first author of the study, added that the research should prompt healthcare providers to offer patients alternatives to cannabis for managing mental health issues. “We hope these findings lead to better patient understanding and more options for treatment that don’t involve cannabis,” she said.

Looking Ahead: Further Research and Public Health Policies on Cannabis Use

While the study provides important insights into the link between cannabis use and psychosis, the researchers acknowledge that more research is needed to fully understand the long-term effects of cannabis on the brain. As cannabis use continues to increase, particularly among adolescents, there is a growing need for policies that address the potential mental health risks of cannabis use.

The research team hopes that their findings will encourage further investigation into the biological mechanisms connecting cannabis use to psychosis and lead to more informed public health policies.

The Growing Need for Cannabis Education and Caution in Use

In light of these findings, it is crucial for both healthcare providers and the public to understand the potential risks associated with cannabis use. As cannabis continues to become more widely accessible, the need for informed cannabis use education is more pressing than ever. The growing body of research linking cannabis use to mental health issues, such as psychosis, calls for greater attention to the long-term effects of cannabis on the brain and the mental well-being of individuals, particularly those who are most vulnerable.

The study marks an important step in our understanding of the relationship between cannabis use and psychosis and highlights the need for continued research and public awareness as cannabis use becomes an increasingly normalized part of society.