The present findings extend previous research with heavy drinking samples and suggest that cue-induced activation of opioid receptor-rich neural regions (Cross et al., 1987; Zubieta et al., 2001), such as the insula and OFC, is moderated by OPRM1 genotype. It is plausible that individuals (G-allele carriers) expressing the more potent mu opioid receptors experience enhanced neural response to alcohol reward-signaling cues and that this pattern of activation provides a neural signature to the enhanced alcohol reward observed in behavioral pharmacology paradigms (Heilig et al., 2011; Ray et al., 2012). Placebo-controlled studies combining fMRI with in-vivo alcohol exposure are needed to more directly test this hypothesis. Nevertheless, these results are generally consistent with the hypothesized role of this genetic marker in alcoholism phenotypes (Ray et al., 2012).
