Quantitative EEG findings in different stage of Alzheimer's Disease

Kwak, Yong Tae

Abstract

BACKGROUND
Although quantitative-electroencephalography (q-EEG) has been used for many years to differentiate Alzheimer's disease (AD) from the healthy aging process, the electrophysiological changes of AD has not been well established due to progressive nature of AD. The aim of this study was to compare q-EEG parameters among elderly controls, patients with mild cognitive impairment group (MCI), and patients with four different stages of AD. Moreover, we tried to identify the variables that are correlated with the degree of cognitive impairment. METHODS: After logarithmic transformation of relative spectral power, we analyzed the topographical relative spectral power and occipital peak frequency in each group. Multiple regression analysis was applied to these variables to identify parameters related with K-MMSE. RESULTS: (1) In AD patients with less than CDR 0.5, peak frequency in occipital lead was significantly lower than that of elderly controls. (2) Compared with elderly controls, AD patients showed significantly reduced left anterior alpha spectral power in CDR 0.5, increased bilateral posterior theta spectral power and reduced generalized alpha spectral power in CDR 1, generalized reduced alpha, beta spectral power and increased theta spectral power in CDR2, generalized reduced alpha and beta spectral power, increased delta and theta spectral power in CDR 3. (3) Korean Mini-Mental State Examination (K-MMSE) score was closely related to left occipital peak frequency, right posterior delta and left anterior theta spectral power. CONCLUSIONS: This study suggests that q-EEG shows different findings in different stages of AD and the left occipital peak frequency is closely correlated with the severity of cognitive dysfunction.