Differential relations among depressive symptoms, global cognition, and multiple measures of everyday function in a sample of community-dwelling older adults

OBJECTIVES: Questionnaire- and performance-based functional assessments for older adults evaluate distinct constructs and may be differentially influenced by cognition or mood. Depression may decrease motivation, impair cognition, and/or bias self-reports of function. The present study evaluated everyday function through multiple methods in a diverse sample of community-dwelling older adults to elucidate depression-cognition-function relations. METHOD: 121 older adults with healthy cognition or mild cognitive impairment completed the Geriatric Depression Scale (GDS-15), cognitive tests, and two everyday function measures: the performance-based Naturalistic Action Test (NAT) and the Instrumental Activities of Daily Living - Compensation (IADL-C) Questionnaire. Study partners also completed the IADL-C. Multivariate regressions examined the influence of total depressive symptoms, global cognition, and their interaction on functional outcomes. Exploratory models investigated apathy- and affect-related depressive symptom influences on function. RESULTS: Global cognition predicted all functional measures. Total depressive symptoms predicted only self-reported function, driven by 'apathy' symptoms. NAT error score was influenced by affect-related symptoms and an apathy-cognition interaction. CONCLUSION: Functional measures are differentially influenced by mood. Self-reports are influenced by apathy symptoms and related motivational changes. Relations between mood and performance-based tasks may depend on symptom types, performance-based variables, and interactions with cognition. Comprehensive assessments should include multiple everyday function measures.