Cognitive impairments in progression of Parkinson's disease.

A total of 88 patients with progression of Parkinson's disease (PD) were studied. Cognitive impairments (CI) in PD were in most cases progressive in nature, predominantly because of increases in the severity of dysregulatory and neurodynamic disorders, impairments to visuospatial functions, and, in some cases, deficits in nominative speech function. A high frequency of transformation of moderate cognitive impairments to dementia was demonstrated over periods of 2-5 years. Predictors of the progression of CI in PD were identified: elderly age, later onset of disease, and the severity of PD. The greatest rate of progression of CI was seen in patients with initially more severe impairments of regulatory and visuospatial functions.