Alzheimer's disease and P300: evaluation of modality and task difficulty

The P300 event-related brain potential (ERP) was elicited in young adults, elderly normals, and Alzheimer patients in the early stages of the disease (n = 12/group). All subjects performed both auditory and visual oddball tasks that varied in target/standard discrimination difficulty. P300 amplitude was smaller and peak latency longer for the Alzheimer patients compared to control subjects in all paradigms. The greatest differentiation between Alzheimer patients and controls was obtained with the relatively easy tasks, especially for the visual modality. The results suggest that the P300 ERP component can provide useful information about Alzheimer's disease during its early stages, and that easy visual tasks are the most sensitive in discriminating patients from unaffected controls.