Studies exploring differential effects of acute alcohol consumption on younger and older adults are lacking within the field of alcohol research, especially those using moderate doses. Previous studies addressing this question have tended to use complex behavioral tasks too broad to isolate specific neurocognitive processes affected by both alcohol and aging. Compromises in cognitive efficiency (i.e., the ability to respond both quickly and accurately) have previously been identified in both elderly and acutely intoxicated individuals.
The present study employed a visual–spatial, 2-choice reaction time (RT) task to evaluate the interactive effects of aging and alcohol on cognitive efficiency. Our primary outcome measure was an efficiency ratio derived from each participant's response accuracy (ACC) and mean RT (%correct/RT). Younger (25 to 35; n = 22) and older (55 to 74; n = 37) participants were randomly assigned to receive either a placebo or moderate alcohol dose intended to produce a peak breath alcohol concentration of 0.04%. Participants performed the task at peak alcohol levels.
A significant interaction between age group and dose assignment was observed, F(3, 55) = 4.86, p = 0.03, for the efficiency ratio. Younger participants who received alcohol performed significantly better than did their older counterparts regardless of alcohol condition and despite no differences in performance between the 2 age groups in the placebo condition. Additional correlation analyses between ACC and RT suggested that moderately intoxicated older adults become more accurate as response times increase. This relationship was not observed in older adults in the placebo condition.
These data suggest that healthy individuals exhibit a differential susceptibility to the effects of alcohol depending on their age. Unfortunately, because of the presumed safety of moderate alcohol doses and a lack of studies investigating the interactive effects of acute alcohol consumption and aging, most individuals are unlikely to be aware of this relationship between alcohol consumption and age.
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