P3 event-related potentials and performance of healthy older and Alzheimer's dementia subjects for music perception tasks.

Abstract

Event-related potentials and performance responses were recorded from healthy older subjects and from subjects with Senile Dementia of the Alzheimer's Type (SDAT) performing six tasks involving auditory discrimination of music stimuli. Tasks included pure tone, timbre, rhythm and interval discrimination, detection of a meter shift, and discrimination of open and closed harmonic endings for chord progressions. Mean P3 latency was longer and performance was poorer for SDAT subjects, but they displayed surprising vigilance and mostly above-chance performance. SDAT subjects had a tendency not found for healthy subjects to produce false alarms on the more difficult tasks. Some SDAT subjects produced clear P3 potentials despite chance level performance. The P3 may thus provide a useful measure of neural and cognitive responses to music despite impaired response processing or confusion in SDAT subjects. Despite severe impairment of memory, language, and several other cognitive functions, persons with Alzheimer's disease (Senile Dementia of the Alzheimer's Type or SDAT) seem to respond to music with remarkable attention and comprehension (Katzman, 1986; Swartz, Hantz, Crummer, Walton, & Frisina, 1989). Several authors of the present report have become aware of this response, both by observations of patients with Alzheimer's disease undergoing music therapy, and by conversations with caregivers and music therapists. In several instances, we have observed patients who engage in music activities in an apparently normal manner, singing songs, dancing, and exercising in synchrony with music. The same patients, however, were apparently unable to produce or fully comprehend normal conversation or to remember that they had recently met a particular individual. In general, responses of Alzheimer's patients to music include body movements and dancing in synchrony with the music, singing, increased socialization, decreased agitation, and overall improvement of mood. Additional reports of the benefits of providing music stimulation to demented patients are given in the literature (Bower, 1967; Charatan, 1980; Clark & Witte, 1991), including for patients in the later stages of Alzheimer's disease (Katzman, 1986; Norberg, Melin, & Asplund, 1986).