Carriers of the rs3778150-C allele reported significantly lower levels of maximum alcohol-related stimulation, as measured by lower StimMax scores (β = −.20, t(133) = −2.34, p = 0.021; ΔR2 = 0.037). In contrast, carriers of the rs3778150-C allele did not differ from rs3778150-T homozygous individuals in their ratings of maximum alcohol-related sedation. Furthermore, although the rs1799971 genotype was not significantly associated with StimMax, the association of rs1799971 with SedMax remained significant in the presence of rs3778150, with carriers of the rs1799971-G allele reporting significantly lower levels of alcohol-related sedation, compared with rs1799971-A homozygous individuals (β = −.21, t(134) = −2.50, p = 0.015). The addition of rs1799971 accounted for an increase of 4.5% in explained variance explained for SedMax, over and above the effects of covariates entered in Step 1. When rs3778150 was entered instead at Step 2, the addition of rs1799971 into the model at Step 3 accounted for an increase of 4.0% of explained variance in SedMax (Table 4).
