EEG Theta and Alpha Reactivity on Opening the Eyes in the Diagnosis of Alzheimer's Disease

Abstract

The objective of this study was to evaluate the contribution of EEG theta and alpha reactivity on opening the eyes, in the diagnosis of slight and moderate Alzheimer's disease (AD). Thirty four patients with AD and a control group of 30 individuals were studied, all being assessed using a neurological evaluation, CERAD neuropsychological battery (consortium to establish a registry for Alzheimer's disease), incorporating the Mini Mental State Examination (MMSE), Clinical Dementia Rating (CDR) and a qEEG analysis of the absolute band power at rest, with the eyes both open and closed. The theta and alpha reactivity indices were calculated on opening the eyes, defined from the relationship between the absolute powers in the respective bands in the periods with the eyes open and with them closed, the quotient of the relationship between the alpha and theta indices, the alpha/theta ratio, was also calculated. Multiple regression models were used to determine the accuracy in discriminating between the AD and control groups. A regression model using only cognitive data provided an accuracy of 92.2%, whereas a regression model combining cognitive data and qEEG measurements provided an accuracy of 95.3% in the classification between AD and the controls. The variable for the qEEG was the left hemisphere alpha/theta index, since the other parameters were shown to be inferior with respect to the clinical data in the regression analysis. The integrated study of the theta and alpha reactivity indices on opening the eyes and the alpha/theta index, was shown to be a useful approach in qEEG in the evaluation of AD and should be evaluated with larger samples and with other data analysis methods, with the aim of increasing the accuracy.