Alcohol intoxication and negative mood similarly affect reward learning but not punishment learning in the Iowa Gambling Task

This study investigated how alcohol intoxication and negative mood affect decision-making in the Iowa Gambling Task (IGT) in a high-risk sample of adults who regularly drink alcohol. Using a 2×2 between-subjects design (N=160), we experimentally manipulated alcohol intoxication (target BrAC=.06% vs. .00%) and mood (negative vs. neutral) and employed computational modeling to identify underlying mechanisms. Results showed that alcohol intoxication impaired IGT performance, with intoxicated participants selecting fewer cards from advantageous decks (estimate=-8.12, 95% CI=[-12.83, -3.23]). Evidence for an effect of negative mood was moderate but inconclusive (estimate=-4.82, 95% CI=[-9.66, 0.02]). Computational modeling revealed that both alcohol (estimate=.13, 95% CI=[.05, .21]) and negative mood (estimate=.12, 95% CI=[.04, .20]) increased reward learning rates without affecting punishment learning rates. No interaction effects were observed. These findings suggest that impaired decision-making during alcohol intoxication and negative mood states stems from heightened sensitivity to immediate rewards rather than diminished sensitivity to punishments but these effects do not appear to be additive, providing novel insights into the computational mechanisms underlying alcohol-related decision-making deficits.