and an OPRM1 × Alcohol interaction (β = −0.49, SE = 0.15, t = −3.26, p< .01). Further, given the genotype group differences on smoking status, all analyses were repeated while controlling for current smoking status. Doing so resulted in all OPRM1 effects remaining statistically significant. These analyses also suggested significant effect of smoking status on self-reports of stimulation (β = −4.64, SE = 1.99, t = −2.34, p< .05) and vigor (β = −0.28, SE = 0.14, t = −2.05, p< .05), such that regular smokers reported less stimulation and vigor across alcohol and saline infusions. Lastly, controlling for sex, sex × alcohol, days since last drink, number of drinking days in the past 30 days, and total number of drinks in the past 30 days, and the DSM-IV symptom of tolerance did not alter any of the significant OPRM1 effects.
