The P3 potential and its clinical usefulness in the objective classification of dementia

Two groups of normal subjects and three groups of demented subjects of specific etiology and severity (mild and moderate arteriosclerotic; moderate Alzheimer's) were compared on the basis of P3 latency and amplitude. P3 latency was found to be a useful parameter for the demonstration of cognitive dysfunction in patients with dementia, which supports the findings of Goodin et al. (1978). Clinically, the efficacy of using P3 latency as an objective test in determining the severity of dementia, can be questioned by two results of this study. First, P3 latency could not separate mildly demented patients from normals. Second, no significant difference was found for counts to the infrequent stimulus between the normal subjects, neurologically-impaired patients and patients with mildly arteriosclerotic dementia. However, P3 latency did enable separation of patients with a moderate classification of dementia from normal subjects. More importantly, P3 latency separated patients with mild and moderate arteriosclerotic dementia. This result indicated that P3 latency was sensitive enough to separate patients with dementia of the same etiology at different stages of the disease.