A neuropsychological comparison of demented and nondemented patients with Parkinson's disease.

The strength and sensitivity of neuropsychological test findings in patients with Parkinson's disease (PD) was reviewed using meta-analytic principles to provide a basis of comparison of deficits in nondemented and demented patients with PD. The review revealed significant relationships among duration of disease, physical disability, and cognitive impairment in nondemented patients, and qualitative and quantitative differences in the pattern of neuropsychological test impairments between nondemented and demented patients with PD. The disparate profiles of neuropsychological impairment in nondemented and demented patients may indeed reflect disease progression in keeping with the significant clinical correlations in nondemented patients. That is, as the duration of the disease endures, it appears that performance on tasks of delayed recall deteriorates first, followed by performance on measures of manual dexterity, cognitive flexibility, and abstraction.