P300 TOPOGRAPHY IN ALZHEIMERS-DISEASE

This study assessed whether P300 scalp topography distinguishes subjec ts with Alzheimer's disease (AD) from controls. Specifically, it was p redicted that the AD group would show maximum P300 amplitude over fron tal areas and the largest P300 reduction over parietal and left hemisp here areas. These hypotheses were tested using a standard auditory odd ball paradigm to compare 26 AD subjects and 26 controls matched on age , sex, handedness, and education. P300 was measured at frontal, centra l, parietal, and occipital sites over left and right hemispheres and a long the midline. Results revealed that the distribution of P300 was d ifferent for the two groups such that the controls manifested a maximu m over parietal areas, whereas the AD subjects showed a maximum at fro ntal sites with the largest reductions in P300 over parietal areas. No hemispheric differences in P300 were found. These results are consist ent with the hypothesis that P300 represents the activity of multiple neural generators that are differentially disrupted by the disease pro cess.