Thus, these studies paint a picture of greater vulnerability to peer alcohol use among adults with the high risk DRD4 genotype -- heavy drinking friends provide alcohol cues that increase the activation of neural reward-craving circuits and subjective craving for alcohol, which, aided by reduced behavioral inhibition and greater social reinforcement for drinking, increases alcohol consumption. By contrast, individuals with the low risk DRD4 genotype may be more immune to alcohol cues provided by heavy drinking friends, better able to inhibit impulses to drink, and less dependent on drinking for social reinforcement. Individual differences in these mechanisms related to DRD4 may become more prominent in adulthood, when the normative development of impulse control is complete, compared to adolescence which is characterized by greater impulsivity and sensation seeking (Steinberg et al., 2008). More research is needed to verify these developmentally-specific mechanisms in the context of the interaction between peer drinking and DRD4 polymorphism.
