[Clinically useful event-related potentials].

Abstract

For clinical use of event-related potentials (ERPs), issues to be solved included individual variations in their latencies and amplitudes, inconsistencies in the abnormalities of these parameters in dementia patients among research institutes, etc. In normal groups, variations in the latency and amplitude of P300 (P3), a representative ERP component, can be resolved by the standardization of several of its biological determinants. The determinants included 1) natural factors, e.g. circadian rhythm, the season, 2) induced factors, e.g. exercise, fatigue, drugs, and 3) constitutional factors, e.g. age, sex. The inconsistency of data among dementia patients is mostly due to differences in the severity or stage of dementia. However, clinically the most important issue is to develop an ERP test to identify mild cognitive dysfunction at an early stage of dementia, which differs from that at an advanced stage. For example, in familial Alzheimer's disease, a test for verbal memory is reported to be the most sensitive. On the other hand, mismatch negativity, one of the early ERP components, is a pre-attentive automatic response to changes in auditory stimuli. Since this component can be evoked without any attention or task, one of its advantages is that it can be recorded in infants or small children, or in demented or comatose patients. Other clinically useful ERP components are also introduced.