Abstract
OBJECTIVE: Previous research shows that executive function (EF) and personality independently predict functional decline. Our objective was to determine whether personality traits predict independence with instrumental activities of daily living (IADLs), after accounting for executive dysfunction, in a mixed sample of patients with amnestic mild cognitive impairment (MCI) and Alzheimer disease (AD). METHODS: In a cross-sectional analysis at a university medical center, 63 healthy older adults (median age: 67.6 years; 71% women) and 119 patients (median age: 75.0 years; 58% women) with varying degrees of AD (probable AD: 85; possible AD: 3; amnestic MCI: 31) were studied. Standardized neuropsychological measures, NEO Five-Factor Inventory (NEO-FFI), and informant-report Lawton and Brody IADL scales were used. All participants underwent neuropsychological evaluation, including administration of self- and informant-report NEO-FFI. Patients additionally underwent neurologic examination, and their informants completed the Lawton and Brody IADL scale. RESULTS: When testing the association between EF and personality on IADLs in the patient sample, conceptual card sorting, informant-report Openness, and informant-report Conscientiousness all significantly predicted IADLs, after accounting for age, education, and depression. In addition, a significant interaction showed that low Conscientiousness and executive dysfunction, in combination, can predict impairment of IADLs. CONCLUSION: Personality has a unique association with IADLs in patients with AD pathology that is not explained by EF. The findings confirm prior speculation that personality, in addition to cognitive dysfunction, is a risk factor for functional decline. Early identification of vulnerable individuals may allow for intervention to prolong functional independence.