Social drinking and cognitive functioning revisited: the role of intellectual endowment and psychological distress

The hypothesis that alcohol consumption affects the cognitive functioning of sober social drinkers was investigated in 140 male World War II veterans. All had been tested on an intelligence test during their army service and retested on the same test in 1984-86 and again in this study. On all three occasions heavy lifetime drinkers had the lowest verbal and nonverbal intelligence scores and moderate drinkers, the highest. Performance declined across test occasions for all groups on the nonverbal subtests. On the verbal subtests performance of light and moderate drinkers improved while that of heavy drinkers did not. After controlling for age, education, young adult intelligence and psychological distress, greater lifetime drinking was significantly associated with poorer performance on two of 17 neuropsychological measures and better performance on one measure, while greater current drinking was associated with poorer performance on one measure. The findings appeared to rule out psychological distress and lower intelligence in young adulthood as alternative explanations of cognitive deficits in social drinkers, but they also suggested that, with these factors controlled, social drinking had relatively circumscribed effects on cognitive functions. Reasons why the present findings might underestimate long-term effects of social drinking are discussed.