Widespread individual differences exist in the manifestation of cognitive deficits in abstinent alcoholics, with 50 to 85 percent of those alcoholics without Korsakoff’s syndrome exhibiting signs of cognitive decline (see Parsons 1993). Thus, anywhere from 15 to 50 percent of abstinent alcoholics may not exhibit any obvious signs of cognitive impairment. Although no single reason can be given to explain the inconsistent relationship between alcohol consumption measures and test performance, researchers have explored numerous possible variables that may account for the relationship (for a review, see Parsons 1993), including the following subject characteristics:
