Differential contributions of cognitive and motor component processes to physical and instrumental activities of daily living in Parkinson's disease

Patients with Parkinson's disease (PD) become dependent upon caregivers because motor and cognitive disabilities interfere with their ability to carry out activities of daily living (ADLs). However PD patients display diverse motor and cognitive symptoms and it is not yet known which are mast responsible for ADL dysfunction. The purpose of this study was to identify the contributions that specific cognitive and motor functions make to ADLs. Executive functioning, in particular sequencing, was a significant independent predictor of instrumental ADLs whereas simple,motor functioning was not. By contrast simple motor functioning, but not executive functioning, was a significant independent predictor of physical ADLs. Dementia severity, as measured by the Dementia Rating Scale, was significantly correlated with instrumental but nor physical ADLs. The identification of selective selective relationships between motor and cognitive functioning and ADLs may ultimately provide a model for evaluating the benefits and limitations of different treatments for PD. (C) 1998 National Academy of Neuropsychology. Published by Elsevier Science Ltd.