Capacity to consent to treatment: empirical comparison of three instruments in older adults with and without dementia.

PURPOSE: The purpose of this study was to compare adults with and without dementia on capacities to consent to treatment as assessed by three instruments. DESIGN AND METHODS: Eighty-eight older adults with mild to moderate dementia were compared with 88 matched controls on four indices of legal competency to consent to medical treatment as assessed with three capacity instruments.
RESULTS: Mean performance of adults with dementia on a legal standard of understanding treatment information was impaired relative to controls on all instruments, and it was also impaired for an appreciation standard on one instrument and a reasoning standard on two instruments. However, in categorical ratings, most adults with dementia were within the normal range on all decisional capacities. Legal standards were operationalized differently across the three instruments for the capacities of appreciation and reasoning. IMPLICATIONS: Most adults with mild dementia can participate in medical decision making as defined by legal standards, although memory impairments may limit demonstration of understanding of diagnostic and treatment information. In dementia, assessments of reasoning about treatment options should focus on whether a person can describe salient reasons for a specific choice, whereas assessments of appreciation of the meaning of diagnostic and treatment information should focus on whether a person can describe the implications of various choices for future states. More research is needed to establish the reliability and validity of assessment tools and of capacity constructs.