Alcohol-induced performance impairment: a 5-year re-examination study in heavy and light drinkers

Ty Brumback, Dingcai Cao, Patrick McNamara, Andrea King

The theory of behavioral tolerance to alcohol posits that greater experience with drinking to intoxication leads to less impaired cognitive and psychomotor performance. However, the degree to which behavioral tolerance develops or changes over time in adults due to repeated heavy alcohol drinking has not been clearly demonstrated. We examined data from the first 6 years of the Chicago Social Drinking Project to test whether chronic heavy drinkers (HDs; n = 86) and light drinkers (LDs; n = 69) exhibit behavioral tolerance or changes in perceived impairment at two testing phases in early adulthood. Tasks were the Grooved Pegboard and Digit Symbol Substitution Test (DSST) given at initial testing and then repeated in a re-examination phase 5 years later. Alcohol (0.8 g/kg) and placebo were administered at separate sessions in each phase for a total of 620 individual laboratory sessions. HDs exhibited less impairment over time on the Pegboard task but not on the DSST, while LDs did not exhibit behavioral tolerance on either task. HDs reported persistently lower perceived impairment compared to LDs. These findings demonstrate that behavioral tolerance in HDs is evident over time on rote fine motor skills (Pegboard) but not more complex skills integrating motor speed, encoding, and short-term memory (DSST). The results have implications for our understanding of alcohol-induced impairments across neurobehavioral processes in heavy drinkers and their ongoing risks for alcohol-related consequences over time.