Acute effect of alcohol on working memory updating

Abstract

Aims: To examine the acute effects of alcohol on working memory (WM) updating, including potential variation across the ascending limb (AL) and descending limb (DL) of the blood alcohol concentration (BAC) time-course. Design: A two-session experiment in which participants were randomly assigned to one of three beverage conditions [alcohol (males: 0.80 g/kg; females: 0.72 g/kg), active placebo (0.04 g/kg) or non-alcohol control (tonic)] and one of two BAC limb testing conditions (AL and DL or DL-only) for the second session, yielding a 3 (beverage) × 2 (time-points tested) × 3 (time-point) mixed factorial design with repeated measures on the latter factor. One of the repeated assessments is ‘missing by design’ in the DL-only condition. Setting: A psychology laboratory at the University of Missouri campus in Columbia, MO, USA. Participants: Two hundred thirty-one community-dwelling young adults (51% female; aged 21–34 years) recruited from Columbia, MO, USA, tested between 2011 and 2013. Measurements: Latent WM updating performance as indexed by shared variance in accuracy on three WM updating tasks (letter memory, keep track, spatial 2-back) at three time-points. Findings: Multi-group modeling of latent WM updating indicated that performance among participants who consumed placebo or control beverages improved during the second session at time-points corresponding to AL (∆ from baseline in latent mean ± standard error (SE) + 0.5 ± 0.01, P < 0.001) and DL (+ 0.08 ± 0.01, P < 0.001). Alcohol consumption did not impair WM updating (∆ from baseline in latent mean ± SE, at AL: + 0.01 ± 0.01, P = 0.56; at DL: + 0.05 ± 0.01, P < 0.001), but attenuated performance improvements (equality of latent means across beverage groups at AL or DL: Δχ2(1) ≥ 7.53, P < 0.01). Conclusions: Acute alcohol-induced impairment in working memory updating may be limited, but dampening of practice effects by alcohol could interfere with the completion of novel, unpracticed tasks.