PC1 was mostly comprised of pleasant effects such as enjoyment and stimulation (defined for subjects as positive stimulation by use of the synonyms lively, up, vigorous and excited), as well as intoxication and estimated number of drinks. The negative subjective effects (anxiety, tiredness) contributed less to PC1. This dichotomy suggests that for heavier drinking individuals who carry the CC genotype at rs279858, the pleasant effects of alcohol persist within an episode of drinking to a greater degree than in lighter drinking CC individuals. These persisting pleasant effects of alcohol could contribute to longer drinking episodes, and so to an increased risk of alcohol use disorders. While our study only assessed recent drinking patterns (within 1–2 months of participation), our finding is consistent with a number of studies showing that recent or extended heavy drinking history is associated with greater positive and stimulating effects of alcohol (i.e. measures such as stimulate, like, want, enjoy) (King et al., 2011; King et al., 2014; Quinn and Fromme, 2011b).
