A massive genetic study has found key genes linked to cannabis use, in an effort to explain why some people are more likely to try or frequently use cannabis, and how this behavior overlaps with mental health and addiction risk.
Researchers analyzed genetic data from more than 131,000 participants of the personal genetics company 23andMe to examine two traits: whether a person had ever used cannabis in their lifetime and how frequently they used it during their heaviest period.
The findings, published in Molecular Psychiatry this week, revealed two genes tied to lifetime use and to frequency, pointing to biological pathways involved in brain signaling, risk-taking, and addiction.
The team of researchers from several Canadian and U.S. academic institutions has found that both lifetime and frequent cannabis use are heritable traits, which means that genetics could help understand who uses cannabis and how often. The analysis confirmed strong genetic links between cannabis use and other forms of substance use, including alcohol and tobacco, as well as psychiatric disorders such as depression and ADHD.
The researchers discovered that lifetime cannabis use is linked to two important genes. The first, Cell Adhesion Molecule 2 (CADM2), helps brain cells connect and communicate, and has been repeatedly tied to traits like risk-taking, impulsivity, and substance use, suggesting it may influence how people respond to rewards and risks. The second is the Metabotropic Glutamate Receptor 3 (GRM3) gene, which regulates communication between brain cells through the chemical glutamate and supports learning and memory. GRM3 has also been linked to psychiatric disorders such as schizophrenia and bipolar disorder, which may link cannabis use and mental health.
Sandra Sanchez-Roige, Ph.D., associate professor of psychiatry at UC San Diego School of Medicine and senior author of the study, said in a statement that “understanding the genetics of early-stage behaviors may help clarify who is at greater risk, opening the door to prevention and intervention strategies.”
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