The scalp topography of P3b in early Alzheimer's disease

Event-related brain potentials (ERPs) were recorded from groups of young and older normal controls, and patients with 'mild' Alzheimer's disease. The major focus of the current study was on group differences in the scalp topography of the P3b component elicited by rare, target stimuli. A young control group was included in order to observe normal age-associated topographic changes and to determine if patients with probable Alzheimer's disease showed an exaggerated pattern associated with pathological aging. During standard and novelty oddball tasks, Alzheimer's patients produced P3b scalp distributions characterized by increasing amplitude from frontal to posterior areas of the scalp, highly similar to the P3b scalp topographies shown by the young controls. The data suggest that P3b topography, in isolation, cannot be used as a 'marker' of 'mild' or early-stage Alzheimer's disease.