Smokers carrying one form of a gene that affects brain cell receptors to the neurochemical dopamine responded to an antidepressant medicine, the researchers explain, while smokers with another form of the gene did not. The findings were reported here Sunday at the American Cancer Society Science Writers Seminar.
Dopamine is a brain chemical that helps produce feelings of pleasure and satisfaction.
Abnormalities in dopamine activity in the brain have been linked to addiction. The researchers ran genetic tests on 134 smokers to determine whether they carried the A1 or A2 form of the DRD2 gene. Individuals with at least one copy of the A1 version of the gene have fewer and less sensitive D2 dopamine receptors than do individuals with two copies of the A2 allele, the researchers explained. This means they have a weaker response to dopamine's effects. The A1 version of the gene has been linked to smoking and other forms of substance abuse.