Visual P300 event-related potentials evoked by patients' own faces in dementia

While P300 event-related potentials (ERPs) are widely used neurophysiologic indices of cognitive function, they are sometimes difficult to record with the conventional oddball paradigm in patients with dementia. To neurophysiologically explore the cognitive functions in such patients, visual ERPs evoked by subjects' own faces (F-VERPs) were studied in 11 patients with dementia, in whom conventional auditory ERPs (C-AERPs) could not be obtained. To record F-VERPs, the subject's own face (target stimuli) and the faces of two unknown persons (nontarget stimuli) of the same gender and approximately the same age as the subject were presented randomly on a computer CRT. During the examination, subjects were asked to silently count the number of target stimuli using their fingers. In 15 healthy controls, P300 latencies in F-VERPs were 16-100 ms longer than those in C-AERPs. All 11 demented patients could identify the target stimuli, and F-VERPs were successfully recorded with pathologically prolonged P300 latencies in eight patients. These findings suggest that for demented patients, the paradigm of identifying their own faces yields more data than the conventional auditory oddball paradigm, and that F-VERPs are more suitable than the C-AERPs for the neurophysiologic evaluation and follow-up of higher cognitive functions in demented patients.