The association between A118G and alcohol dependence may be explained by different physiological responses to alcohol based on A118G genotype. People with the 118G variant have a stronger association between their desire to drink and subsequent drinking than people lacking the variant [98]. Two studies have also shown that heavy drinkers carrying the G allele have increased craving compared to individuals with the A/A genotype, although an additional study found conflicting results [99-101]. These findings included increases in cue-induced craving and G carriers are known to have greater response in the mesocorticolimbic regions of the brain following alcohol cues [99, 102]. Responses in these regions have been associated with increased alcohol craving, suggesting a potential mechanism behind the craving associated with A118G [103]. People carrying the 118G allele also experience more euphoria and subjective “highs” after drinking alcohol [101, 104]. Positron emission tomography scans of male social drinkers with the 118G variant showed a greater increase in dopamine release in the ventral striatum following alcohol consumption, compared to A/A participants, possibly explaining the increased feeling of euphoria [105].
