Cognitive Correlates of Impaired Testamentary Capacity in Alzheimer's Dementia

Testamentary capacity (TC) is a legal construct about the ability to make or change a will. Although studies of financial and medical capacities have noted a strong association between capacity and cognition, no study has examined the cognitive correlates of TC in Alzheimer's disease (ad).

Study participants were 22 cognitively healthy controls and 20 persons with mild to moderate ad who were administered a neuropsychological battery and the Testamentary Capacity Instrument (TCI), a new performance-based measure of TC. Both TCI Element and TCI Total scores were calculated. TCI Total scores were calculated for the purposes of expanding correlational analyses (i.e., Pearson's product-moment) and are not intended for forensic TC evaluations. Final predictors were identified using linear and logistic regression modeling.

All ad participants but one obtained TCI Totals that fell >2.5 standard deviations below the control group mean. Initial cognitive correlates of TCI performance were measures of general cognition, language, verbal memory, executive function, and processing speed. The four cognitive variables showing the highest t values and correlating with TCI Total score > 0.7 were entered into logistic and linear regression models. Final predictor models consisted of measures of verbal memory, executive function, and semantic knowledge and demonstrated shared variance of 0.71 (linear) and 0.82 (logistic).

A diagnosis of ad dementia is associated with clinical impairment in TC and associated cognitive abilities and indicates that a legal assessment of TC is warranted. Second, the results offer insight into the cognitive basis of TC in persons with Alzheimer's dementia.