OBJECTIVE. To investigate the performance of cognitively demanding instrumental activities of daily living (IADLs) among people with Parkinson’s disease (PD) without dementia.

METHOD. Seventy-seven participants with PD and 57 participants without PD underwent standardized, performance-based IADL evaluation using the Performance Assessment of Self-care Skills. Activity performance was rated for independence, adequacy, and safety.

RESULTS. The PD group had lower independence and adequacy scores than the non-PD group for almost every activity. Medication management, shopping, and sharp utensil use were the activities most sensitive to group differences. In the PD group, older age, lower Mini-Mental State Examination scores, and decreased motor function were associated with poorer IADL performance.

CONCLUSIONS. People with relatively early and mild PD demonstrated measurable deficits in the performance of cognitively demanding IADLs. This work highlights the importance of using objective assessments of IADL function to detect early functional changes in people with PD.