In order to investigate the relationship between environmental factors and results of psychiatric examinations, a questionnaire survey studying these factors and neurophysiological examinations (electroncephalography (EEG), somatosensory evoked response (SER) and contingent negative variation (CNV)), as well as clinical neuropsychiatric examinations and intelligence scale (Hasegawa's dementia rating scale (HDRS) and Kohs's blocking design test (KBDT)), were performed on 41 healthy aged (61-80 years old) who were participants in programs of Osaka Prefectural Center for the elderly. Initial examinations were conducted in 1983 and the second in 1988 on the same subjects for the purpose of measuring the aging process over 5 years with regard to brain function. A total of 29 subjects, for a participation rate of 82.9% (excluding deceased and those who moved away from the area), attended the second examination. The results are summarized as follows. 1. When environmental factors were compared for 1983 and 1988, a reduction in participation in social activity was observed in some of the aged in 1988, although differences in their daily living situations were unchanged. 2. The mean scores of HDRS and KBDT were 31.9, 98.6 in 1983 and 30.2, 94.6 in 1988 respectively, with only 2 subjects showing considerable decline of intelligence. 3. With regard to the neurophysiological examinations, the number of subjects with peak latencies of SER that were abnormally prolonged increased in 1988, while there was little difference in their EEGs between 1983 and 1988. 4. From these results, it appears that the relation between declines in brain function and environmental factors, involves multiple factors that will require further study.