Measuring the course of Alzheimer's disease. A longitudinal study of neuropsychological function and changes in P3 event-related potential.

On two occasions one year apart, the cognitive performance of 12 patients with presenile dementia Alzheimer type (ATD) and 14 with alcoholic Korsakoff syndrome (KS) was assessed both psychologically using the Christensen version of Luria's neuropsychological investigation and physiologically by measuring P300 (P3) and other long-latency auditory event-related potentials. All patients with ATD showed evidence of psychological deterioration and most also showed changes in auditory P3, whereas on all measures the KS group remained essentially unchanged. The extent of the changes in the ATD group varied, but in general those patients with most psychological deterioration also displayed the biggest changes in P3 wave form. There were two patterns of decline: a majority followed the traditional progressive course associated with Alzheimer disease; and in a minority, decline was slower. Methods for determining the rate of decline in individual patients with ATD, together with the prognostic implications, are discussed.