Heavy Smoking, Difficulty Quitting Are Associated With Genes, Study Says

New research out of New Zealand suggests that DNA may play a role in determining whether a person ends up a smoker and how easily it will be for them to quit smoking.

The researchers developed a "genetic risk profile" for smokers by using genetic clues gleaned from decades of smoking research.

They tested the durability of the risk profile on 1,000 New Zealanders who are taking part in the Dunedin Study -- a long-term, ongoing study of New Zealanders born between 1972 and 1973.

Using the genetic risk profile, the researchers sought to identity whether individuals at high genetic risk became addicted to cigarettes more quickly as teens and whether, as adults, thy had a more difficult time quitting.

Participants with high-risk genes were found to have smoked about 7,300 more cigarettes than the average smoker by the age of 38, according to a write-up of the study by U.S. News and World Report.

High-risk participants were also found 27 percent more likely to become hooked on nicotine and 22 percent more likely to fail attempts to quit smoking compared to people with lower genetic risk scores.

A person's genetic risk profile did not predict whether the person would try smoking cigarettes, about 70 percent of the field had tried. But for those who did try smoking, having a high-risk genetic profile predicted increased likelihood of heavy smoking and nicotine dependence, even higher than a family history of smoking the study found.

The connection between smoking and the genetic risk profile was most apparent in teenagers; among teens who tried smoking cigarettes, those with a high-risk genetic profile were 24 percent more likely to become smokers by age 15 and 43 percent more likely to be smoking a daily pack of cigarettes by age 18.

"The effects of genetic risk seem to be limited to people who start smoking as teens," said author Daniel Belsky, a post-doctoral research fellow at Duke University. "This suggests there may be something special about nicotine exposure in the adolescent brain, with respect to these genetic variants."

The results of the study are published JAMA Psychiatry.