Heterogeneity of cognitive impairment in progressive supranuclear palsy, Parkinson's disease, and Alzheimer's disease.

Patterns of cognitive and behavioral impairment were analyzed in patients with progressive supranuclear palsy (PSP), Parkinson's disease (PD), and senile dementia of Alzheimer's type (SDAT), matched for age, sex, manual laterality, educational level, and degree of intellectual deterioration. The scores of the three groups of patients were significantly lower than those of controls and were comparable on tests of verbal and visuospatial functions as well as global memory. Patients with SDAT could be distinguished by the severity of verbal memory disorders; patients with PSP, and to a lesser degree those with PD, by impaired performances on tests sensitive to frontal lobe dysfunction.