Differentiation of Dementia of the Alzheimerʹs Type From Depression With Cognitive Impairment on the Basis of a Cortical Versus Subcortical Pattern of Cognitive Deficit

This study compared 15 “mildly” cognitively impaired participants with Dementia of the Alzheimer Type (DAT), 15 depressed cognitively impaired participants (DCI), and 15 normal participants. The participants were matched for age, and reading ability, and were tested on a series of cognitive instruments selected on the basis of their ability to distinguish a cortical versus subcortical pattern of deficit. The DAT group demonstrated impaired performances on tests of language, praxis and gnosis. Deficits in these areas were absent from DCI group. There were differences between all of the groups on the California Verbal Learning Test, but after this effect was controlled using an analysis of covariance procedure, the differences in tests of gnosis, praxis and language function between the DCI and the DAT participants still remained. These findings support the clinical usefulness of the cortical-subcortical distinction in differentiating DCI from DAT.