Diagnostic usefulness of cognitive auditory event-related P300 subcomponents in patients with Alzheimers disease?

Early diagnosis of Alzheimers disease (AD) would be of great clinical value. Auditory event-related P300 mainly generated in temporoparietal regions is related to the pathophysiology of AD. A former study revealed that reliable separation of P300 subcomponents by dipole source analysis increased sensitivity (86.7%) and specificity (76.7%) in correctly detecting AD patients from healthy subjects. Aim of the present study was to replicate this interesting finding on a different sample. Auditory event-related P300 was recorded in unmedicated patients with mild to moderate AD and age- and sex-matched healthy volunteers. The subcomponents of the P300, P3a and P3b, were determined by dipole source analysis (Brain Electric Source Analysis program). As in the first study, AD patients were again characterized by a diminished P3b amplitude and longer P3a latency and reaction time. Using these three parameters, sensitivity was 81.3% to detect patients with AD from healthy controls with a specificity of 83.3%. This successful replication of the first study suggests that recording and determining P300 subcomponents together with other putative neurobiological markers may be useful to enhance the individual diagnostic accuracy in AD at an early stage.