Predictors of Decisional Capacity in Alzheimer's Disease Biomarker Test Candidates

Deciding to learn one's Alzheimer's disease (AD) biomarker status is a high-stakes endeavor that requires comprehending and deliberating about complex and nuanced information. Assessing capacity to consent to AD biomarker testing and disclosure is further complicated when candidates have cognitive impairment and present with family care partners.

The objective of this analysis was to identify predictors of decisional capacity for an amyloid positron emission tomography disclosure study among persons with mild cognitive impairment (MCI) and their family care partners.

This analysis used an analytical correlational design, using baseline data from a randomized controlled trial of amyloid positron emission tomography results disclosure. Simple linear regression was used to examine predictors of decisional capacity. Focusing on persons with MCI, the predictor variables of interest were sociodemographic characteristics, level of knowledge of MCI/AD, global cognition, and neuropsychological tests of language and executive functioning. Dyadic analyses were conducted with data from 82 dyads of persons with MCI and care providers using the Actor-Partner Interdependence Model to assess for presence of actor and partner effects among key variables.

Capacity-to-consent scores demonstrated sufficient capacity for all participants to consent to the study. For persons with MCI, lower age, higher mental status scores, MCI/AD knowledge scores, and better performance on measures of language and executive functioning were predictors of decisional capacity. The model revealed positive actor relations for MCI/AD knowledge with decisional capacity for both persons with MCI and family care partners and negative partner relationships for family care partners' MCI/AD knowledge with the decisional capacity of persons with MCI.

Assessment of decisional capacity is imperative when considering participation in AD research, including studies with high-stakes procedures like biomarker results disclosure. Our findings highlight that not only do individual characteristics put persons with MCI at risk for lower decisional capacity, but dyadic effects from family care partners may also be present.