A study published yesterday in the journal JAMA Psychiatry found a link between 3 genetic markers and symptoms of marijuana dependence — a terrible, life-altering condition in which people can’t stop using the drug even though it interferes with many aspects of their lives, like relationships or work.

In addition, the study showed some overlap between the genetic risk factors for marijuana dependence and the genetic risk factors for depression, suggesting a possible reason why the these two conditions are often found together.

Researchers analyzed information from more than 14,000 Americans who took part in 1 of 3 studies looking into the genetics of substance-use disorders. Between 18% and 36% of the people in these studies had marijuana dependence. The researchers looked for genetic variations, known as single-nucleotide polymorphisms, or SNPs, that were linked with symptoms of marijuana dependence.

They found 3 genetic variants that were linked with these symptoms. One of these genetic variants was located in a gene involved in regulating calcium concentrations in blood. Previous studies have found that calcium signaling in the body is important in other substance-use disorders, like opioid dependence.

The investigators hope the new findings will help lead to a better understanding of the biology of marijuana dependence. It’s estimated that 9% of people who use marijuana will become dependent on it, according to the National Institute on Drug Abuse (NIDA).