The Mental Deterioration in the Aged and the Computerized EEG Analysis

Abstract

SUMMARY The relationship between the computerized EEG data and the mental function was studied in 73 subjects aged 60 and over in a home for the aged. The mental function was examined by Hasegawa Test (HT) (simplified dementia rating scale) and Bender Gestalt Test (BGT), and the degree of the mental deterioration was classified as normal, sub‐normal, pre‐dementia, dementia of HT, and as (‐), (+), (++), (+++) of BGT. The EEG records were analyzed quantitatively at resting state with eye‐closed and also at eye‐opened state. EEG variables were compared in each group of the two tests and the both states. The following results were obtained. EEG variables correlated more closely with the score of BGT than that of HT in general. The percent time alpha and alpha continuity at the eye‐closed state decreased significantly in dementia group of HT and (+++) group of BGT. With the progress of the deterioration of BGT, the percent time alpha at the eye‐opened state gradually increased, and the ratio of the percent time alpha at the eye‐opened state to the eye‐closed state increased lineally. With the progress of the deterioration of BGT, the percent time theta increased gradually, and the number of theta waves over the amplitude of 30 μV increased lineally especially in the central area at eye‐closed state. By eye opening the number of theta waves over 30 μV decreased significantly in (‐) and (+) groups of BGT, but did not change in (++) and (+++) groups. The peak frequency and the percent time beta did not correlate with the mental function in the aged. Parts of this paper were presented at the 5th Annual Meeting of Japan EEG and EMG Society, Tokyo, December, 1975 and at the 6th Annual Meeting, Fukuoka, November, 1976.

Longitudinal Changes in Computerized EEG and Mental Function of the Aged: A Nine-Year Follow-Up Study

“…The amount of alpha waves has been reported by many authors to decrease in elderly people, or in cases of dementia (Mundy-Castle et al, 1954;Mankowski & Belonog, 1971), but we reported in a cross-sectional study (Miyasaka et al, 1978) that the percent time alpha did not decrease in the elderly until mental deterioration had advanced. Our finding in the present study of the preservation of percent time alpha until the early eighties is consistent with a cross-sectional study of Matejeck (1980) and with our previous study.…”

“…Part of that study has already been reported (Miyasaka & Nakano, 1981;Nakano & Miyasaka, 1982). We report here quantitative analysis of EEG changes and comparison with changes of psychometric data.…”

“…This finding of the decrease in fast waves from early senescence is consistent with the longitudinal study of Obrist et al (1961) and the cross-sectional study of Matejeck (1980). In a previous cross-sectional study (Miyasaka et al, 1978), no correlation between the amount of beta waves and the degree of mental deterioration was found. Although the decrease in fast waves might be related to advanced deterioration in brain functions, it seems to have no clear correlation to mild mental deterioration.…”

Sleep and quantitative EEG in neurodegenerative disorders

“…Some reported that decreases of relative power in the alpha and beta bands and increases of power in the delta band were correlated with severity of AD [28]. Others obtained relationships only with percent alpha and delta [29,30], while others found either percent theta [31], percent beta [32] or mean power [33,34] to be the best correlates of AD severity.…”