The strongest evidence that low P3 amplitudes predate the development of alcoholism comes from ERP studies of subjects at risk for developing alcoholism (see sidebar). Begleiter and colleagues (1984) first reported low P3 amplitudes in sons of alcoholic fathers who were not administered alcohol at the time of the test. This finding has been replicated in several laboratories under many different experimental conditions in both older and younger at-risk subjects. Nevertheless, although most studies have confirmed these results, some studies have not. Low P3’s are most likely to be observed in studies of prepubescent sons of alcoholic men during the performance of difficult visual tasks (Polich et al. 1994). Significantly, however, low P3’s have been detected in all studies that examined offspring of type II alcoholics. Type II alcoholics have an early onset of alcoholism (often during adolescence) with a high rate of relapse and frequently accompanied by petty criminality. This form of alcoholism is thought to have a large genetic component (Cloninger 1987).
