New evidence connects DNA to how we relate to cannabis
In one of the largest genetic studies of its kind, researchers have found that certain genes linked to cannabis use also connect to a range of mental health, cognitive, and physical traits. The work, conducted by scientists at the University of California, San Diego, in collaboration with the DNA testing company 23andMe, suggests that an individual’s genetic makeup may influence not only whether they try cannabis, but how often they use it and the chances of developing problematic use.
Published in Molecular Psychiatry, the study analyzes genetic data from more than 130,000 participants who reported their cannabis use and provided DNA samples. Using a genome-wide association study (GWAS) approach, the team identified two major genetic players and a broader network of genes that correlate with lifetime cannabis use and usage frequency.
Two leading genetic players in cannabis behaviours
The researchers highlighted two key genes:
- CADM2 (Cell Adhesion Molecule 2) – a gene involved in brain cell communication. CADM2 has previously been linked to impulsivity, obesity, and certain cancer risks, suggesting it could influence behavioural choices and how people respond to cannabis cues.
- GRM3 (Metabotropic Glutamate Receptor 3) – linked to brain plasticity and psychiatric conditions such as schizophrenia and bipolar disorder. Variants in GRM3 may shape how the brain adapts to cannabis exposure and stress, potentially affecting risk for heavier use.
Beyond these two genes, the study identified 40 additional genes associated with lifetime cannabis use and four connected to how frequently people use cannabis, with 29 of these newly implicated in cannabis research. When researchers compared their results with large US health databases, they found substantial genetic overlaps with over 100 other traits, including ADHD, anxiety, depression, risky behaviours, and even certain physical conditions like diabetes and chronic pain.
Genetics, environment, and the risk of addiction
Scientists caution that possessing a particular gene does not deterministically predict cannabis use disorder. Instead, genetic factors appear to shape intermediate traits and susceptibilities that, in conjunction with environment, lifestyle, and personal choices, influence whether cannabis use escalates into problematic use. “Understanding the genetics of early-stage behaviours may help clarify who is at greater risk, opening the door to prevention and intervention strategies,” said Dr. Sandra Sanchez-Roige, the study’s lead investigator.
Dr. Hayley Thorpe, a postdoctoral researcher involved in the study, echoed the idea that genetics map the trajectory from initial exposure to potential addiction. By focusing on intermediate traits, researchers hope to map how genetic risk unfolds before cannabis use disorder develops, enabling targeted prevention and early intervention efforts.
What this means for public health and future treatments
The study’s authors emphasize that cannabis use exists on a continuum—from trying cannabis to daily use—and that genetics may help explain why some individuals traverse this path while others do not. In a world where cannabis use is rising globally, understanding the genetic underpinnings could inform public health strategies and pave the way for personalized approaches to prevention and treatment.
Global statistics underscore the scale of the issue. The World Health Organization estimates roughly 147 million people worldwide use cannabis, with a significant subset at risk for use disorder. In Europe, about 8.4% of adults aged 15–64 reported cannabis use in the past year, equating to around 24 million people, with daily use remaining a minority but clinically important concern.
Looking ahead
As science continues to map the genetic architecture of cannabis behaviours, researchers anticipate a future where genetic insights inform early screening, behavioral interventions, and possibly pharmacological strategies aimed at reducing harm and supporting at-risk individuals. The study’s findings are a reminder that genetics is a piece of a larger puzzle—one that includes environment, lifestyle, and choices—and that prevention efforts must consider this complex interplay.
