D2 DOPAMINE-RECEPTOR GENE AND CIGARETTE-SMOKING - A REWARD GENE

There is now growing evidence that the less prevalent allele (A1) of t he D-2 dopamine receptor (DRD2) gene is strongly associated with sever e alcoholism. Similarly, subjects who abuse illegal drugs or who are o bese also show a significantly higher prevalence of the A1 DRD2 allele compared to controls. Moreover, cigarette smokers, both past and curr ent, demonstrate significantly higher prevalence of the A1 allele than nonsmokers. In as much as alcohol, cocaine, opiates, nicotine and foo d are known to increase brain dopamine levels and activate the mesocor ticolimbic dopaminergic reward pathways of the brain, it is hypothesiz ed that an inherited deficit of D-2 dopamine receptor numbers in brain reward areas of A1 allelic subject predisposes them to substance abus e problems.