Usefulness of Quantified-EEG in Alzheimer's Disease

ABSTRACT

BACKGROUND: The conventional electroencephalography (EEG) is commonly used as an aid in the diagnosis of Alzhiemer's disease (AD). Recently developed quantitative electroencephalography (qEEG) provides data that are not achievable by conventional EEG. Nevertheless, the clinical reliability and usefulness of spectral analysis and topographic mapping is still a matter of controversy in the diagnosis of Alzheimer's disease. The aim of this study was to compare the topographical quantitative EEG (qEEG) changes between elderly controls and AD patients. METHODS: We analyzed the absolute, relative spectra power and occipital peak frequency taken from 16 derivations by averaging twenty-2-sec epoch in elderly controls and AD patients. After logarithmic transformations of absolute and relative power, a statistical test was done and occipital peak frequency was compared with each other. RESULTS: (1) Compared with normal controls, AD patients had a significantly lower alpha and beta spectra power as well as a significant higher delta spectra power. (2) In AD patients, the peak frequency in occipital lead had a significantly lower frequency than that of elderly controls. (3) Korean Mini-Mental State Examination(K-MMSE) scores were closely related in delta and alpha band power in nearly all electric leads. (4) Compared to absolute power, relative power was a more sensitive tools in detecting changes of EEG in AD patients. CONCLUSIONS: This study suggests that qEEG is a useful tool for detecting the electroencephalographic changes of AD, and correlated with the severity of cognitive dysfunction. Moreover, absolute and relative spectra power is complementary in the clinical utility of qEEG.