Can’t stop smoking? Your genes might be part of the problem.
After a case review of 24 studies involving 29,000 participants, researchers at Washington University in St. Louis determined that smokers who carried a relatively common genetic marker tend quit smoking four years later on average than those without. The genetic variation was also linked to earlier diagnoses for lung cancer.
Principal investigator and psychiatrist Dr. Li-Shuin Chen said it’s likely the gene marker—rs16969968—makes people react to nicotine in a way that makes addiction particularly hard to kick.
“We think the risk variant is likely to make the smokers more compulsive, have more cravings and withdrawl,” Chen said. “Over time, it becomes a severe addiction.”
It’s a bit like musical taste or a preference for spicy food. What jives for some doesn’t jive for everyone.
But unlike spicy food, the nicotine addiction can be deadly. Those additional years of smoking may then increase a person’s chances of developing related illnesses such as lung cancer, Chronic Obstructive Pulmonary Disease (COPD) and heart disease, Chen said. If people know they have the marker, they could take preventive measures and begin cancer screenings at an earlier age, she added.
The studies Chen’s team reviewed only included people of European descent where the genetic marker occurs in 42 percent of the population. She said it’s likely that different genetic markers have the same link to nicotine addiction for African American and Asian populations, but there hasn’t been enough research.
“The way this science is progressing, there is more genetic information available in subjects of European ancestry. We’re hoping to increase awareness that we need to learn about other populations,” Chen said. She expects findings for African American and Asian populations to come out next year.
Studies linking the science of addiction to a person’s genetic makeup are growing in size and scope. Certain genes have been found to predispose or protect people from alcoholism, and other gene markers are linked to a higher rate of opiod addictions, such as heroin. In an interesting twist, the same variation that increases a person’s risk of nicotine dependence makes it less likely they will develop an addiction to cocaine, Chen said.
Environmental factors, such as family members who smoke, stress and early exposure to tobacco, play a major role in addiction. Some people caution against putting too much weight on studies that connect addiction to genetics because it may deter a person from seeking treatment if they believe their condition is unchangeable.
But understanding how genes play into addiction can help doctors target the type of treatment they recommend to patients. Chen points to her previous research, which shows that people with a genetic predisposition to smoking are three times more likely to kick the habit with the help of nicotine-replacement patches, gum and other medications. But people without the variant are unlikely to respond to those treatments at all.
With a smorgasbord of FDA-approved cigarette addiction treatments at her disposal, Chen said her researchers are now running studies to work out which genetic markers react well with each treatment.
“Our goal is to find out if we can use genetic information to predict who responds to which medication, to increase the efficacy, make the medication more effective and decrease the side effects,” Chen said.
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