Electroencephalographic coherence in Alzheimer's disease: comparisons witha control group and population norms

Previous research from independent laboratories has shown reduced electroen cephalographic coherence in patients diagnosed with dementia of the Alzheim er type (DAT). This study added to this work by comparing interhemispheric and intrahemispheric coherence in nonmedicated DAT patients (n = 35) with t hat of a normal control group (n = 30), as well as with a data bank of popu lation norms. Raw and Z-score transformed values showed reduced coherence, interhemispherically tin delta, theta, alpha, and beta bands) and intrahemi spherically (delta and theta bands) in DAT patients with both comparison pr ocedures. Discriminant analysis correctly classified 73% to 75% of patients . The results are discussed in relation to earlier research, "trait" versus "state" factors, the cholinergic system, and cognitive processes in dement ia.