New Genetic Study Links Cannabis Use to Psychiatric, Cognitive, and Physical Health Risks
October 13, 2025 – SAN DIEGO – A new large-scale genetic study has uncovered critical links between cannabis use and various psychiatric, cognitive, and physical health risks. Researchers at the University of California San Diego School of Medicine, in collaboration with genetic testing company 23andMe, have identified specific genes associated with cannabis use. The findings could pave the way for targeted prevention and treatment strategies for cannabis use disorder.
The study, published on October 13, 2025, in Molecular Psychiatry, offers new insights into the genetic factors that influence cannabis use and its potential long-term effects on health. Despite the widespread use of cannabis, its full impact on health remains largely underexplored. The researchers hope this study will serve as a foundation for future treatments and interventions for cannabis use disorder (CUD), a condition that can severely affect a person’s daily life.
“Cannabis is widely used, but its long-term effects on health remain poorly characterized,” said Sandra Sanchez-Roige, Ph.D., associate professor of psychiatry at UC San Diego and senior author of the study. “Understanding the genetics behind cannabis use can help us develop better strategies to prevent and treat cannabis use disorder.”
Understanding the Genetics Behind Cannabis Use
The team conducted a genome-wide association study (GWAS), analyzing genetic data from 131,895 23andMe participants. These participants provided information on their cannabis use, answering questions about whether they had ever used cannabis and how frequently they consumed the drug.
The results of the study identified two key genes—Cell Adhesion Molecule 2 (CADM2) and Metabotropic Glutamate Receptor 3 (GRM3)—that are linked to cannabis use. The CADM2 gene, which plays a role in cell assembly and nerve signaling in the brain, was found to be associated with both the likelihood of trying cannabis and the frequency of use. Previous studies have already linked CADM2 to impulsivity, obesity, and even cancer metastasis.
The second gene, GRM3, plays a significant role in communication between neurons and is critical for long-term brain plasticity. This gene has previously been linked to psychiatric disorders such as schizophrenia and bipolar disorder, suggesting a complex relationship between cannabis use and mental health conditions.
“Our study shows that cannabis use is genetically linked to not only psychiatric traits but also cognitive abilities and physical health outcomes,” said Sanchez-Roige.
New Genetic Insights into Cannabis Use
In a secondary analysis, the researchers identified an additional 40 genes associated with lifetime cannabis use and four genes linked to the frequency of use. Remarkably, 29 of these genes had never before been connected to cannabis-related traits.
Moreover, the study found that both lifetime cannabis use and frequency of use were genetically correlated with over 100 different traits. These included various psychiatric conditions such as anxiety, depression, ADHD, and schizophrenia, as well as cognitive traits like executive function and risk-taking behavior. Physical health problems, including diabetes, chronic pain, and coronary artery disease, were also linked to genetic predispositions for cannabis use.
The findings also revealed a genetic overlap with other behaviors and health risks, such as tobacco use and infectious diseases like HIV and viral hepatitis. These insights suggest that cannabis use could share genetic pathways with other conditions, making it an important factor to consider when addressing overall health and wellness.
Implications for Prevention and Treatment
This research is one of the first to examine the genetic factors that precede cannabis use disorder. As cannabis use exists on a spectrum—from occasional use to dependence—the study focused on understanding the genetic risks that could lead to cannabis use disorder (CUD).
“By studying these intermediate traits, we can begin to understand how genetic risk develops before cannabis use disorder fully manifests,” said Hayley Thorpe, Ph.D., the study’s first author and a postdoctoral researcher at Western University. “This could help identify individuals at higher risk and offer early interventions to prevent the disorder.”
At present, there are no FDA-approved treatments specifically for cannabis use disorder, which highlights the need for targeted therapeutic approaches. The hope is that the genetic discoveries made in this study will guide future research into developing preventative and therapeutic interventions for CUD.
A Collaborative Effort
The study involved an extensive collaboration between UC San Diego and 23andMe, with additional contributions from Western University and Vanderbilt University Medical Center. The research was funded by the National Institutes of Health’s Institute on Drug Abuse, and the Tobacco-Related Disease Research Program.
Importantly, the study also highlights the power of genetic research to inform health strategies and improve our understanding of behavioral disorders. By leveraging genetic tools such as GWAS, scientists can pinpoint molecular systems that connect cannabis use with broader patterns of brain function and behavior.
Looking Ahead
As cannabis use continues to rise globally, understanding its long-term effects on mental and physical health is more critical than ever. The insights from this study offer an important first step in deciphering the genetic underpinnings of cannabis use, and they may soon help scientists and healthcare professionals identify new ways to mitigate its risks. The authors are optimistic that their findings will be a cornerstone for developing both prevention strategies and effective treatments for cannabis use disorder.
