Caregivers' judgments of the functional abilities of the Alzheimer's disease patient: a comparison of proxy reports and objective measures.
The assessment of functional capacity is essential for the diagnosis of dementia by DSM-IV criteria and has important implications for patient intervention and management. Although ratings of functional disability by family or other proxy informants are widely used by clinicians, there have been concerns and empirical evidence that potential reporter biases may result in either overestimation or underestimation of specific functional deficits. In this study, we compared family members' judgments of the functional abilities of seventy-two patients diagnosed with Alzheimer's disease (AD). These judgments were compared to actual objective functional performance on an array of real-world tasks using the Direct Assessment of Functional Status (DAFS) scale. The results indicate that caregivers were extremely accurate in predicting the functional performance of AD patients who were not impaired during objective evaluation. In contrast, caregivers significantly overestimated the ability of impaired AD patients to tell time, to identify currency, to make change for a purchase, and to utilize eating utensils. Higher patient MMSE scores were associated with caregivers' overestimation of functional capacity, while the degree of caregivers' depressive symptoms, as measured by the CES-D depression scale, was not related to either overestimation or underestimation of patients' functional performance.