A new study suggests a specific genetic variation may increase the risk of developing marijuana-related psychosis. Researchers found people with the variation were twice as likely to develop a psychotic disorder when using marijuana. The risk increased up to sevenfold if they used marijuana daily, HealthDay reports.

The findings could help lead to new treatments for marijuana-induced psychosis, the researchers say.

In the journal Biological Psychiatry, they note evidence is increasing that marijuana use during the teenage years may increase the risk of developing schizophrenia. Their study of more than 700 people found marijuana-related psychosis was linked with a variation in the AKT1 gene. The gene is involved in the regulation of the brain chemical dopamine, which plays an important role in mental health, the article notes.

“Our findings help to explain why one cannabis user develops psychosis while his friends continue smoking without problems,” the researchers from King’s College London’s Institute of Psychiatry note in a news release.

A study published last year suggested marijuana may accelerate the onset of psychotic disorders in some young users. Researchers conducted a review of the literature examining the effects of marijuana, alcohol, and other drugs on the onset of psychiatric disorders such as schizophrenia. They found patients with psychotic disorders who smoked marijuana at an early age developed symptoms almost three years sooner than those who did not. The link was strongest among those who started smoking at ages 12 to 15 or younger.