Studies with both humans and nonhumans suggest that the traits associated with AUDs have a genetic basis. Thus, identifying the genes involved could help to identify neurochemical pathways that are important in the development of alcohol abuse. Preuss et al. (2001) investigated the association between impulsivity as measured by the BIS in relation to the G-1438A polymorphism in the promoter region of the 5-HT2A receptor gene in alcohol dependent individuals. Participants with low scores on the BIS reported a later age of onset of alcoholism than the subjects with high scores, and impulsivity was associated with 5-HT2A 1438A alleles (Preuss et al., 2001). Limosin et al. (2003) investigated the dopamine receptor D2 (DRD2; specifically the Taql A polymorphism) gene in relation to BIS scores among alcohol dependent individuals (n = 92). A2/A2 and A1/A2 genotypes scored higher on global impulsiveness than Al/Al genotype. The authors propose that delay discounting and other aspects of reward-dependent impulsiveness may constitute a risk factor for the development of alcohol dependence, and that this could be partly mediated by the DRD2 gene (Limosin et al.,
