Electrophysiologic validation of two categories of dementias--cortical and subcortical.

: Recently, the dementias have been classified into 2 categories-Cortical (CD) and Subcortical (SD). Some studies have questioned this classification. We attempted to validate the classification on electrophysiologic grounds. Fourteen of 15 patients with SD had relatively normal EEGs as compared to only 3 of 15 patients with CD, matched for age, sex and severity of dementia (p greater than 0.01). SER test results were often abnormal in the SD group but always normal in CD patients. These preliminary data appear to validate the classification of dementias into SD and CD categories.