Cognitive Correlates of Instrumental Activities of Daily Living Performance in Parkinson Disease Without Dementia

To investigate cognitive correlates of instrumental activities of daily living (IADL) performance among people with Parkinson disease (PD) without dementia. Cross-sectional. Academic medical center. Volunteer sample (N=161) comprising participants with PD without dementia (n=102) and healthy comparison (HC) participants (n=59). Not applicable. Performance-based assessment of cognitively-demanding IADL (meal preparation, bill paying, shopping, medication management, small home repair), neuropsychological tests (attentional control/flexibility, planning, working memory, memory, crystallized intelligence), and measures of motor function and other characteristics (eg, depressive symptoms). There were no group differences in neuropsychological test performance (P>.06). The PD group performed more poorly than the HC group on a number of cognitive IADL tasks (P<.04). After accounting for the effects of motor impairment and other disease-related characteristics, neuropsychological test performance accounted for a small but unique portion of the variance in performance of all cognitive IADL combined, meal preparation, shopping, and medication management in the PD group (R2=4%-13%; P≤.01). The PD group had cognitive IADL performance limitations despite being unimpaired on neuropsychological tests. Within PD, neuropsychological test performance accounted for a small but significant portion of the variance in cognitive IADL performance over and above the effects of motor and other impairments. These results support the added value of using performance-based IADL assessments in functional evaluations of individuals with early and mild PD without dementia.