People who carry a specific high-risk variation in a cluster of nicotine receptor genes are more likely to find success in quitting smoking using smoking cessation medication, a new study suggests.

Researchers from the Washington University School of Medicine in St. Louis studied variations in a cluster of genes that have been shown to contribute to nicotine dependence and heavy smoking, UPI reports.

“People with the high-risk genetic markers smoked an average of two years longer than those without these high-risk genes, and they were less likely to quit smoking without medication,” researcher Li-Shiun Chen, MD said in a news release. “The same gene variants can predict a person’s response to smoking-cessation medication, and those with the high-risk genes are more likely to respond to the medication.”

The high-risk smokers were three times as likely to be successful in quitting smoking if they used smoking cessation medication, compared with low-risk smokers. The researchers said their findings suggest it may one day be possible to predict who will be most likely to benefit from medication to treat nicotine addiction.

The study appears in the American Journal of Psychiatry.