Genetics: Smoking Signals

May 14, 2013

Let’s face it: Warnings regarding teenage smoking are as earth-shattering as those about alcohol’s deleterious effects behind the wheel. But new research from a team of U.S., U.K., and New Zealand geneticists adds an interesting caveat to the common wisdom. It turns out that teenagers with high-risk genetic profiles for becoming heavy smokers are far more likely to become addicted to smoking and have a harder time quitting as adults than those without the same precondition.

Researchers first examined earlier studies and developed a genetic-risk profile for heavy smoking. By studying prior genome-wide associations (GWAS) of adult smokers, the researchers were able to identify variants common to the heaviest smokers. The variants were located in and around genes that affect how the brain responds to nicotine and how nicotine is metabolized.

The team then looked at a long-term study of 1,000 New Zealanders from birth to age thirty-eight and identified whether individuals with this high-risk genetic profile got hooked on cigarettes more quickly as teens and whether, as adults, they had a harder time quitting. Those with the high-risk profile were more likely to become daily smokers as teens, and were more likely to have failed in attempts to quit as adults.

“Teens at a high genetic risk transitioned quickly from trying cigarettes to becoming regular, heavy smokers."

“Genetic risk accelerated the development of smoking behavior,” says Daniel Belsky, a postdoctoral research fellow at Duke’s Center for the Study of Aging and Human Development and the Institute for Genome Sciences & Policy. “Teens at a high genetic risk transitioned quickly from trying cigarettes to becoming regular, heavy smokers.”

However, a person’s genetic risk profile did not predict whether the person would try cigarettes in the first place. The study showed that those who smoke cigarettes only on weekends or only one or two per day had even lower genetic risk than nonsmokers.

Study participants who did not become regular, heavy smokers during their teens appeared to be “immune” to genetic risk for adult smoking problems.

“The effects of genetic risk seem to be limited to people who start smoking as teens,” says Belsky. “This suggests there may be something special about nicotine exposure in the adolescent brain, with respect to these genetic variants.”