Predictors of performance-based measures of instrumental activities of daily living in nondemented patients with Parkinson's disease.

Few studies have examined instrumental activities of daily living (iADLs) in nondemented Parkinson's disease (PD), and the majority of these studies have used report-based measures, which can have limited validity. The present study had two main goals: (a) to examine the performance of nondemented PD patients on two performance-based measures of iADLs, which are considered more objective functional measures, and (b) to examine the cognitive, motor, and psychiatric correlates of iADL impairment in PD. Ninety-eight nondemented PD patients and 47 healthy older adults were administered performance-based measures that assess the ability to manage medications (Medication Management Ability Assessment) and finances (University of California, San Diego, UCSD, Performance-based Skills Assessment), the Mattis Dementia Rating Scale to assess global cognitive functioning, the Unified Parkinson's Disease Rating Scale Part III to assess motor symptom severity, and the Geriatric Depression Scale to assess depressive symptoms. Nondemented PD patients demonstrated significantly impaired scores relative to the healthy comparison group on the performance-based measure of financial management, but there were no significant group differences in medication management. Global cognitive functioning, motor severity, and depressive symptoms did not correlate with scores on either of the functional measures, except for a small correlation between depressive symptoms and financial management. The two performance-based measures of iADL functioning did not correlate with one another. These findings suggest that medication and financial management may not be predicted based on global cognitive functioning and that iADLs may not be represented by a single construct. Furthermore, these findings suggest the potential need for a multidimensional approach to assessing iADLs.