Scientists at the University of California San Diego School of Medicine, working with the genetic testing company 23andMe, have discovered new links between cannabis use and certain genes in our DNA.
Their findings help explain why some people are more likely to use cannabis or develop cannabis use disorder (CUD), which can interfere with daily life. The study was published in the journal Molecular Psychiatry.
Cannabis, also known as marijuana, is widely used across the world. But while many people try it, not everyone becomes addicted. Experts estimate that about 30% of cannabis users may go on to develop cannabis use disorder. Until now, scientists didn’t fully understand how our genes might play a role in this risk.
To learn more, researchers studied genetic data from more than 130,000 people who use 23andMe and agreed to take part in scientific research. These participants answered questions about whether they had ever used cannabis and how often they used it.
Then, the researchers used a method called a genome-wide association study (GWAS) to find patterns in their DNA that were linked to cannabis use.
The results pointed to two important genes. One is called CADM2, which helps brain cells connect and send messages. This gene has already been linked to traits like being impulsive, having a higher risk of obesity, and some types of cancer.
The researchers found that people who had certain versions of this gene were more likely to try cannabis and use it more frequently.
The other gene is GRM3, which helps the brain process information and stay flexible. This gene has been linked to mental health conditions such as schizophrenia and bipolar disorder. Finding a connection between this gene and cannabis use gives more evidence that there’s a strong tie between cannabis and psychiatric health.
The researchers didn’t stop there. They also found 40 other genes related to lifetime cannabis use and four more genes connected to how often people use cannabis. Most of these genes had never been linked to cannabis before.
Next, they wanted to see what health problems were linked to a genetic tendency to use cannabis. They looked at massive health databases from the NIH and Vanderbilt University, covering thousands of medical traits.
They discovered that people who were genetically more likely to use cannabis were also more likely to have conditions like ADHD, anxiety, depression, schizophrenia, chronic pain, diabetes, and even heart disease.
They also found connections between cannabis use and other risky behaviors, such as tobacco use and risky sex that could lead to infections like HIV and hepatitis. Some genes were also linked to autoimmune diseases.
This study is one of the first to look at what happens in the brain and body before someone develops cannabis use disorder. Instead of just studying addiction itself, the researchers looked at early behaviors—like trying cannabis or using it regularly. They believe this helps them understand how genetic risk builds up over time.
Right now, there are no approved drugs to treat cannabis use disorder. But the scientists hope that their findings will one day help doctors predict who is most at risk and guide the development of new treatments. With more research, these discoveries could lead to better ways to prevent or treat cannabis-related problems before they become serious.
