Smokers’ ability to quit linked to genetic makeup
■ Adults with a high risk of heavy smoking and nicotine dependence smoke longer and have more trouble quitting than others, a new study says.
When helping patients to quit smoking, physicians need to understand that an individual’s ability to kick the habit is related, in part, to his or her genetic makeup, said psychiatrist Li-Shiun Chen, MD, MPH, ScD.
Adults with genetic variants that put them at high risk of heavy smoking and nicotine dependence smoked longer than those without such genetic markers. These adults also were less likely to quit without the help of medication, such as bupropion, according to a study published online May 30 in The American Journal of Psychiatry.
“It’s great for physicians to understand that not everyone can quit smoking easily on their own,” said Dr. Chen, lead author of the study and assistant professor of psychiatry at Washington University School of Medicine in St. Louis. “The genetic testing is not all worked out yet, but in the future, we are hoping to tailor appropriate [smoking cessation] treatment for our patients using their genetic makeup and other risk factors.”
A person’s risk of heavy smoking and dependence on nicotine are associated with variants in a cluster of nicotine receptor genes, CHRNA5-CHRNA3-CHRNB4, according to the study.
Researchers examined data on 5,216 smokers who were 45 to 64 years old when they joined the Atherosclerosis Risk in Communities study in 1987.
They also looked at data on 1,073 adults 18 and older who joined a three-year smoking cessation study at the University of Wisconsin Center for Tobacco Research and Intervention between January 2005 and June 2007.
Researchers found the median age for quitting smoking was 57 among those with the high-risk form of the gene cluster, compared with 55 for other participants (link).
Genetics will enable us “to help patients quit earlier, and that will decrease a lot of smoking-related disorders,” Dr. Chen said.
People with high-risk genetic markers were more likely to fail in their attempts to quit smoking when treated with placebo, compared with those with low-risk genes, the study said. But medications used for nicotine cessation increased the likelihood of kicking the habit in the high-risk group. People in this group were three times as likely to quit smoking with the help of pharmacologic treatments than were people with low-risk genetic markers.
The findings indicate that individuals with low-risk genes likely will be able to quit successfully without the help of smoking-cessation medications, Dr. Chen said.
More research is needed to identify other genes that affect nicotine dependence and smoking-cessation treatment outcomes, said David Shurtleff, PhD, acting deputy director of the National Institute on Drug Abuse. That information could enable physicians to tailor care for smokers, improve their quality of life and reduce the nation’s health care costs, he said.
Using genetics in this way will have “a tremendous impact” on medicine and public health, he said.