Auditory event-related potentials in different types of dementia.

Auditory event-related potentials were recorded in demented, drug-free patients with Huntington's disease and Alzheimer's disease, as well as in demented and nondemented patients with Parkinson's disease, who were matched for age, duration and stage of the disease. The normal P3 latency at a given age was predicted by using an age regression equation that had been calculated on the basis of the findings in 42 normal adults. Using this procedure, a prolonged P3 latency was found in about two thirds of demented patients, irrespectively of the underlying disease. Although the prolonged P3 latency proved to be useful electrophysiological correlate of dementing illness, no differences were found between the observed groups in respect to other components of the auditory event-related potentials (N1 and P2).