Intellectual and memory impairment in moderate and heavy drinkers

Heavy drinkers (more than 2 liters of wine per day), without clinical evidence of brain dysfunction, moderate drinkers (1 liter of wine per day) and control subjects (no more than 250 cc of wine per day) were given the Progressive Matrices test and two learning tests, one tapping verbal memory and the other spatial memory. Heavy drinkers' performance was significantly worse than that of the other groups on the Progressive Matrices test and the spatial learning test. With a more lenient method of analysis, the difference between heavy drinkers and controls on the verbal learning test and that between moderate drinkers and controls on the Progressive Matrices test were also significant. When the influence of intelligence on memory performance was partialled out by covarying memory scores for Progressive Matrices scores, all differences on the verbal learning test disappeared whereas the spatial learning test still discriminated heavy drinkers from mild drinkers and controls. The bearing of these findings on the continuum of impairment hypothesis and the right hemisphere vulnerability hypothesis is discussed.