Individuals with the 118G allele have been reported to be more sensitive to the stimulating and reinforcing effects of alcohol and to experience higher levels of craving for alcohol (Ray and Hutchison, 2004; van den Wildenberg et al., 2007; Miranda et al., 2010; Ray et al., 2010). It has been further postulated that a medication that reduces feelings of euphoria after alcohol consumption may be more successful among individuals with a genetic predisposition to greater feelings of euphoria (Ray and Hutchison, 2004). Indeed, in several studies the polymorphism has also been found to affect the efficacy of naltrexone and naloxone with the individuals carrying at least one G allele showing better responses, but also contradictory findings have been reported (reviewed by Chamorro et al., 2012).
