Evaluation of P300 components for emotion-loaded visual event-related potential in elderly subjects, including those with dementia

Aim: In the present study, the P300 component of the emotion-loaded visual event-related potential in response to photographs of babies crying or smiling was measured to evaluate cognitive function in elderly subjects, including those with dementia. Methods: The subjects were 48 elderly people who consulted a memory disorder clinic. The visual event-related potential was measured using oddball tasks. Brain waves were recorded from four sites. We analyzed the P300 amplitude and latency. Subjects were divided into three groups (the dementia with Alzheimer's disease group [ADG]; the intermediate group [MG], and the healthy group [HG]) based on the Revised Hasegawa Dementia Scale, Mini-mental State Examination scores and the Clinical Dementia Rating. Results: For all subjects, there was a significant positive correlation between P300 latency and Z-score of voxel-based specific regional analysis for Alzheimer's disease for crying or smiling faces. There was a negative correlation between P300 amplitude and Z-score for the crying face. MG subjects were divided into two groups (high risk: HRMG, low risk: LRMG) based on Z-scores (HRMG >= 2.0). The P300 amplitude of ADG was significantly smaller than that of HG, and the P300 latency of ADG was significantly longer than those of other groups for crying or smiling faces. The P300 latency of HRMG was significantly longer than that of LRMG for the smiling face. Furthermore, the P300 latency for the crying face was significantly shorter than that for the smiling face in HG and ADG. Conclusion: These findings suggest that analysis of P300 components of the emotion-loaded visual event-related potential may be a useful neuropsychological index for the diagnosis of Alzheimer's disease and high-risk subjects.