Cognitive determinants of decisional capacity in neurodegenerative disorders.

Objective: Cognitive contributions to decisional capacity are complex and not well understood. Capacity to consent for research has been linked to executive function, but executive function assessment tools are imperfect. In this study, we examine the relationship between decisional capacity and a newly developed executive function composite score and determine whether cognitive performance can predict impaired decisional capacity.

Methods: This is a cross sectional study of participants at the National Institutes of Health with frontotemporal dementia-amyotrophic lateral sclerosis spectrum disorders enrolled between 2017 and 2022. A structured interview tool was used to ascertain research decisional capacity. Study participant Uniform Data Set (v3.0) executive function (UDS3-EF) composite score, Clinical Dementia Rating Scale©, and Neuropsychiatric Inventory was determined.

Results: A decrease in UDS3-EF composite score significantly increased the odds of impaired decisional capacity (OR = 2.92, 95% CI [1.66-5.13], p = 0.0002). Executive function was most impaired in frontotemporal dementia (-2.86, SD = 1.26) and least impaired in amyotrophic lateral sclerosis (-0.52, SD = 1.25) participants. The UDS3-EF composite score was also strongly correlated to the Clinical Dementia Rating Scale©.

Interpretation: Decisional capacity is intrinsically related to executive function in neurodegenerative disorders, and executive dysfunction may predict a lack of decisional capacity alerting investigators of the need for additional scrutiny during the informed consent process.