Direct and indirect assessment of functional abilities in patients with Parkinson’s disease transitioning to dementia

Cognitive impairment is common in patients with Parkinson’s disease (PD), and evaluation of functional abilities is crucial for diagnosis of dementia. OBJECTIVE: We evaluated differences between direct and indirect functional assessment methods to evaluate functional abilities in PD patients. METHODS: We evaluated 32 patients with PD and suspected mild dementia using direct and indirect assessment methods. RESULTS: There was a significant difference between the scores of direct and indirect methods of assessment. Patients and close informants usually overestimated their abilities in many ADL. However, all functional assessment tools used in this study had a relatively good accuracy to predict abnormal performance in a global cognitive scale. Patients with normal cognition according to scores in a global cognitive scale may have some functional impairment in ADL. Direct Assessment of Functional Ability (DAFA) scores correlated linearly with scores in global cognitive scales, and especially with scores in the domains of memory and concentration. CONCLUSION: Patients and close informants usually overestimate their instrumental abilities in ADL. The direct assessment of daily functioning was more reliable than indirect tools to assess functional losses in patients with PD. Finally, some patients with PD but no dementia may present functional losses in ADL.