Aphasia, apraxia, and agnosia in the diagnosis of dementia.

The association of aphasia, apraxia and agnosia with cortical but not subcortical dementias, is a widely held belief. The purpose of the present study was to determine the frequency of aphasia, apraxia, and agnosia in groups of cortical and subcortical dementia patients, and to assess the diagnostic utility of these symptoms. Subjects were 64 patients with subcortical dementias (Parkinson's disease and normal pressure hydrocephalus) and 192 patients with cortical dementia (probable Alzheimer's disease) matched for sex, age, and Mini-Mental State Examination score. Each patient was evaluated for the presence of aphasia, apraxia, and agnosia. Results indicated that only aphasia was reported significantly more often in cortical dementia patients than in subcortical dementia patients. The presence of either of these three symptoms has very low diagnostic sensitivity, specificity, and total predictive value. The severity of the patient's dementia was predicted whether the patient had aphasia or apraxia; type of dementia had no predictive value. These data led to the conclusion that cortical and subcortical dementias cannot be reliably dissociated on the basis of aphasia, apraxia, or agnosia.