August 11, 2008
Genetic Achilles Heel For Nicotine Addiction

If you have the less common rs16969968 form of the CHRNA5 gene and you smoke a cigarette you are more likely to get hooked. Yet another reduction in the possible scope for free will.

In a paper published in the September issue of the journal Addiction, , a multi-university collaborative team of researchers specializing in statistical genetics, gene analysis, and trait analysis reports an association between a variant in the CHRNA5 nicotine receptor gene, initial smoking experiences, and current smoking patterns.

The genetic and smoking data come from 435 volunteers. Those who never smoked had tried at least one cigarette but no more than 100 cigarettes in their lives, and never formed a smoking habit. The regular smokers had smoked at least five cigarettes a day for at least the past five years.

The regular smokers in the study were far more likely than the never-smokers to have the less common rs16969968 form of the CHRNA5 gene, in which just one base-pair in the gene sequence was different from the more common form. This kind of genetic variation is called a single nucleotide polymorphism or SNP.

Smokers were also eight times as likely to report that their first cigarettes gave them a pleasurable buzz.

"It appears that for people who have a certain genetic makeup, the initial physical reaction to smoking can play a significant role in determining what happens next," says senior author and project leader, Ovide Pomerleau, a professor of psychiatry at the University of Michigan Medical School and founder of the U-M Nicotine Research Laboratory.

"If cigarette smoking is sustained, nicotine addiction can occur in a few days to a few months," he adds. "The finding of a genetic association with pleasurable early smoking experiences may help explain how people get addicted and, of course, once addicted, many will keep smoking for the rest of their lives."

Among those who ever try smoking this gene explains only part of the difference between those who become addicted and those who do not. Expect more discoveries of genes that contribute to the odds of getting addicted.

We are witnessing an acceleration of the rate of discovery of genetic factors that influence behavior. This acceleration in the rate of discovery will accelerate as DNA testing costs continue to drop. So expect to see many more reports of genes that influence behavior.

Share |      Randall Parker, 2008 August 11 11:24 PM  Brain Addiction


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