Evaluation of influential factors of cognitive impairments in idiopathic Parkinson's disease.
Using multivariate analysis, we investigated the influence on cognitive functions of aging, brain atrophy, incidental cerebral hyperintensities (CHs), medication, and severity, duration and the initial symptoms of the disease in 53 patients with idiopathic Parkinson's disease (PD). We semiquantitatively assessed the degree of brain atrophy and CHs based on previously established methods. Cognitive functions were significantly and diffusely impaired in PD when compared with controls who were matched for age as well as for the degree and location of CHs. Patients with PD, however, had larger ventricles. Prefrontal dysfunctions were associated with a variety of predictors such as CHs, brain atrophy, severity of PD and medication whereas dorsolateral frontal functions were related simply to age and CHs in the periventricular region. Posterior brain functions had association with severity of illness, ventricular dilatation and total CH score. Clinically observed cognitive impairments in PD may consist of cognitive defects intrinsic to the disease which are variously modified by these factors. It is essential to consider all these predictors simultaneously in any discussion of cognitive functions in PD.