Visual evoked potentials in mild senile dementia of Alzheimer type.

Visual evoked potentials (VEPs) to chessboard shift and to flash stimulation were recorded from 40 subjects with senile dementia of Alzheimer type (SDAT) and 40 individually matched control subjects. All of the SDAT subjects had only a mild degree of dementia and were still living in the community. Analysis of variance showed significant differences between demented and control group means for 3 chessboard shift VEP measures, the demented group having longer latency of peaks P3 and N3, and larger amplitude of segment N2-P3. These three are the earliest reported changes in the VEP in Alzheimer disease, since the flash VEPs showed no measure in which the demented and control group means differed significantly.