Multiple studies provide several clues to the mechanisms through which the long allele of DRD4 may increase susceptibility to peer alcohol use in adulthood. This polymorphism is associated with increased self-reported cravings for alcohol in response to alcohol cues (Ray et al., 2010), perhaps as a result of greater neural response to alcohol cues in the mesocorticolimbic reward-craving pathway (Filbey et al., 2008). In turn, greater craving increases the perceived value of alcohol and is associated with maladaptive patterns of drinking (MacKillop et al., 2007, 2010). Similarly, increased neural activation in the reward-craving pathway is related to higher alcohol use (Filbey et al., 2008). The DRD4 high risk genotype has also been linked with poorer response inhibition and lower neural activation in related neural networks (Filbey et al., 2012), so these individuals may be more likely to act on their alcohol cravings. Finally, individuals with the long DRD4 allele experience greater social bonding when using alcohol with others (Creswell et al., 2012), which may further reinforce patterns of social drinking.
