Neuropsychological performance within-person variability is associated with reduced treatment consent capacity

The capacity of older adults to make healthcare decisions is often impaired in dementia and has been linked to performance on specific neuropsychological tasks. Within-person across-test neuropsychological performance variability has been shown to predict future dementia. This study examined the relationship of within-person across-test neuropsychological performance variability to a current construct of treatment decision (consent) capacity.

Participants completed a neuropsychological test battery and a standardized capacity assessment. Standard scores were used to compute mean neuropsychological performance and within-person across-test variability. Assessments were performed in the participant's preferred location (e.g., outpatient clinic office, senior center, or home). Participants were recruited from the community with fliers and advertisements and consisted of men (N = 79) and women (N = 80) with (N = 83) or without (N = 76) significant cognitive impairment. Participants completed the MacArthur Competence Assessment Tool-Treatment and 11 neuropsychological tests commonly used in the cognitive assessment of older individuals.

Neuropsychological performance and within-person variability were independently associated with continuous and dichotomous measures of capacity, and within-person neuropsychological variability was significantly associated with within-person decisional ability variability. Prevalence of incapacity was greater than expected in participants with and without significant cognitive impairment when decisional abilities were considered separately.

These findings are consistent with an emerging construct of consent capacity in which discrete decisional abilities are differentially associated with cognitive processes and indicate that the sensitivity and accuracy of consent capacity assessments can be improved by evaluating decisional abilities separately.