P300 assessment of early Alzheimer's disease.

The P300 (P3) event-related brain potential (ERP) was elicited in 16 demented patients presumed to be in the early stages of Alzheimer's disease and 16 normal control subjects well matched for age, sex, education and occupational level. All subjects performed a simple auditory discrimination task in which a target tone was presented randomly on 20% of the trials. P3 amplitude was smaller and peak latency longer for the Alzheimer patients compared to control subjects. A second ERP task also was administered in which the target tone occurred 50% of the time. Analysis of the target/standard tone presentation sequences indicated that the Alzheimer patient group demonstrated less amplitude difference between the target and standard sequences and longer overall latencies compared to the control group. The results suggest that the P3 ERP component from auditory stimuli can provide useful information about Alzheimer's disease during its early stages.