Oct. 14, 2003 Philadelphia, PA -- Smokers with a specific combination of two genetic variants may be more likely to remain abstinent and less prone to relapse when trying to quit smoking, a study by researchers from the Tobacco Use Research Center of the University of Pennsylvania School of Medicine indicates. This research – which will appear in the October issue of Health Psychology- has important implications for the development of more effective treatment strategies that are tailored to individual smokers' needs.
"While previous research has examined the effects of genes related to dopamine, a chemical in the brain associated with reinforcing the effects of nicotine, this study provides the first evidence that genes that alter dopamine function may influence smoking cessation and relapse during treatment," said lead author Caryn Lerman, Ph.D., Associate Director for Cancer Control and Population Science at the Abramson Cancer Center of the University of Pennsylvania and Professor in Penn's School of Medicine and the Annenberg Public Policy Center.
Dr. Lerman led a research team that examined 418 smokers enrolled in a randomized placebo-controlled clinical trial of bupropion for smoking cessation. Participants provided blood samples and received bupropion or placebo plus seven sessions of behavioral group counseling. Smoking status, abstinence symptoms and side effects were recorded weekly, and smoking status was verified at the end of treatment and again at a six-month follow-up appointment.
Researchers found that participants with particular variants of the SLC6A3 dopamine transporter gene and the DRD2 dopamine receptor gene reported significantly higher abstinences rates and a longer time before relapse than smokers carrying other variants of these genes. "This gene-gene interaction provides new evidence for the effects of dopamine genes on prospective smoking cessation and underscores the importance of not limiting genetic investigations of smoking behavior to single gene effects," said Lerman.
In previous research, the same variant of the dopamine transporter gene has been associated with higher levels of dopamine in the brain and this may facilitate smoking cessation. "Future smoking cessation studies should evaluate genetic predisposition, as well as the influence of psychological and environmental factors that may promote relapse," stated Lerman.
This research will appear in Health Psychology in an article titled "Effects of Dopamine Transporter and Receptor Polymorphisms on Smoking Cessation in a Bupropion Clinical Trial."
This research was funded by the National Cancer Institute and the National Institute on Drug Abuse and was conducted by the University of Pennsylvania/Georgetown University Transdisciplinary Tobacco Use Research Center.
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