QUANTITATIVE EEG CORRELATES OF COGNITIVE DETERIORATION IN THE ELDERLY

We report on the quantitative analysis of the EEG (QEEG), using the Ne urometric method, in large samples of normal elderly; normal subjectiv ely impaired elderly; patients with mild cognitive impairment; patient s presenting with a continuum of primary cognitive deterioration from mild to moderately severe as measured by the Global Deterioration Scal e (GDS), compatible with dementia of the Alzheimer's type (DAT). Neuro metric QEEG measures were found to be a sensitive index of degree of c ognitive impairment, especially reflected in increased absolute and re lative power in the theta band, with delta increasing in later stages of deterioration. While these abnormalities were widespread, neither l ocalized or lateralized, MANOVA's for GDS and relative power in theta reached highest significance in a bilateral temporo-parietal are. A po ssible relationship between hippocampal dysfunction, cognitive deterio ration, and theta abnormalities is discussed in relation to these find ings. The results suggest that Neurometric QEEG features are sensitive to the earliest presence of subjective cognitive dysfunction and migh t be useful in the initial evaluation of patients with suspected demen tia, as well as in estimating the degree of cognitive deterioration in DAT patients.