Patterns of neuropsychological performance in Alzheimer's disease patients with and without extrapyramidal signs.

We investigated the relationship between extrapyramidal signs (EPS) and the cognitive function in 90 patients meeting NINCDS-ADRDA criteria for probable Alzheimer's disease (AD) by dividing them into those showing no evidence of EPS and those showing at least one EPS on the Unified Parkinson's Disease Rating Scale. Cognitive function was assessed by neuropsychological tests of verbal memory, orientation, abstract reasoning, language, and construction. Patients with EPS were significantly more impaired than patients without EPS on tests of short-term learning and memory, orientation, naming, verbal fluency, and construction, but not on tests of long-term memory, abstract reasoning, or verbal comprehension. These results could not be explained by any differences in age, education, or disease duration between the groups. Since this pattern of neuropsychological impairment resembles that of patients with Parkinson's disease and other EPS syndromes, we hypothesize that EPS are associated with neuropathologic and neuropsychological changes that are superimposed over the classic features of AD.