Computer analysis of EEG activity in dementia of the Alzheimer's type and Huntington's disease.

Computer analysis of the EEG was obtained in the course of evaluation of 35 patients with Dementia of the Alzheimer's Type (DAT) and Huntington's disease (HD), and compared to 20 age-matched normal controls. On-line computer analysis of the EEG consisted of: 1) compressed spectral array (CSA) displays (2-6 channels); 2) relative frequency power (4 bands) and 3) an averaged frequency power function [( alpha/alpha + theta power (microV 2)] X 100 = % EEG Power function). Frequency power reflected increased theta, and reduced alpha components, in patient groups. Significant correlation was obtained between % EEG Power function, and clinical stage of dementia. This function correctly identified 17/25 DAT, and 7/10 HD patients, and gave additional quantification to the primary EEG.