Neuropsychological measures and single photon emission computed tomography in the differentiation and classification of cerebral perfusion deficits in Alzheimer's dementia

Abstract

The accurate diagnosis of Dementia of the Alzheimer's Type (DAT) continues to be an area of difficulty for the fields of neuropsychology and neurology. The introduction of new medications that appear to mediate the insidious progression of the disorder increases the need for timely differentiation of DAT from other dementia-related disorders. The present study examined the relationship between hemispheric differences in regional cerebral blood flow with corresponding lateral neuropsychological processing deficits in patients with DAT. Eighty patients with a diagnosis of DAT were administered Single Photon Emission Computerized Tomography (SPECT) scans and a battery of left and right hemisphere neuropsychological-based tasks. The results of ANOVA indicated that patients with DAT who were not suffering from perfusion deficits exhibited significantly fewer neuropsychological deficits than did patients with DAT who had perfusion deficits. The neuropsychological tests that measured verbal ability, logical memory, word-pair learning, reading, arithmetic, and visual-perceptual organization were all significantly lower in the group with perfusion deficits. Further analysis indicated that patients with left hemisphere perfusion deficits tended to have poorer neuropsychological skills than did individuals with right hemisphere perfusion deficits, diffuse perfusion deficits, and no perfusion deficits. A Stepwise Discriminant Analysis was unable to use the neuropsychological variables to classify patients accurately into perfusion deficit groups.