Genes may determine how people can best quit smoking

  How to Kick the Habit of smoking May Be A Question of Genetics

Genetics may play a role in the success of smoking cessation programs, according to a study presented yesterday at the American Cancer Society?s (ACS) 43rd Science Writers Seminar in Dana Point, Calif.

"The way health care is structured, nicotine dependence treatments typically get short shrift. We ask people to give up a very addictive drug with little intervention. One size doesn?t fit all," says study author Paul M. Cinciripini, PhD, associate professor and director of the tobacco research and treatment program and deputy department chair at the University of Texas M.D. Anderson Cancer Center.

Negative Mood and Genetics

"We know that many people relapse after initial success, usually within the first few weeks after quitting," Cinciripini says. Smokers say the emotional ?low? they feel after they quit causes them to start smoking again, he says.

In the study, 134 participants were given either an antidepressant called venlafaxine, or a placebo, which has no effect on the body. All of the patients were treated with nicotine patches and standard behavioral therapy. The researchers wanted to know if the antidepressant helped people quit smoking, and if people who had a specific gene associated with nicotine, alcohol and cocaine dependence were more likely to start smoking again than people who did not have the gene.

According to Cinciripini, researchers believe that those carrying the gene might have fewer or less sensitive dopamine receptors in the brain. Dopamine is a chemical messenger in the brain that is associated with the sensation of reward or pleasure. Receptors are the molecules on the surface of the cells that respond to the dopamine signal.

Understanding Addiction at a Molecular Level

The study revealed two things: first, people who took the antidepressant did better than people who didn?t. About 37% of those on the drug kept their resolve not to smoke at the end of the 18-week drug treatment, compared to about 25% of the participants who were given the placebo. Second, participants who had the gene were more prone to start smoking again during the 18 weeks after they had quit, that those who did not carry the gene. Cinciripini says. The authors of the study also noted that this particular gene, which predisposes a person to become a smoker and addicted to nicotine, might also make it more difficult to quit, even when medication is used.

The study participants showed a different response to the mood-improving effects of venlafaxine depending on their genetic pattern , says Cinciripini. People with the gene responded poorly to the drug, when compared to those who did not have the gene.

This study will help researchers begin to understand the process of nicotine addiction and how different people handle nicotine at the molecular level, according to Harmon Eyre, MD, chief medical officer for the ACS. "This study is very important in that it opens up avenues of understanding different genetic make-ups, and how individuals will respond to smoking cessation."

"The information gained in this study could prompt further research using genetic testing to pinpoint who will respond to specific types of drug treatment," Cinciripini says. "Understanding how our genes influence our behavior, and how genes might predict which drugs would be successful in which patients, as demonstrated in this study, is going to help guide the treatments prescribed for patients and improve the success of those treatments," he says.

More than 70% of the 50 million smokers in the U.S. have tried to quit at least once, about 46% try to quit every year, and most smokers make several attempts to stop before successfully kicking the habit, according to the U.S. Surgeon General.

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