Abstract
OBJECTIVE: Everyday functional capacity in older adults is influenced by several factors, with prior studies finding that cognition mediates the relationship between depression and everyday functioning. However, these studies utilized samples with low depression severity and used only one type of functional assessment. We aimed to examine whether cognition mediates the relationship between depression and functioning in older adults with a history of treatment-resistant depression. METHOD: Data from 383 participants enrolled in the OPTIMUM Neuro study were analyzed. Participants completed a neuropsychological assessment battery, depression severity interview, self-/informant-rated functioning measures and a performance-based functioning measure. Linear regression was used to determine whether depression scores predicted cognitive domain and everyday functioning scores. Cognitive domain scores predicted by depression were then tested as mediators between depression and functioning. RESULTS: Higher depression symptoms predicted poorer performance on all measures of functioning as well as the cognitive domains of attention, executive functioning, and immediate memory. Immediate memory partially mediated the relationship between depression and a performance-based measure of functioning, while attention and executive functioning partially mediated the relationship between a self-report measure of functioning and depression. CONCLUSIONS: The relationship between depression severity and poorer functional performance was partially mediated by attention, executive functioning, and immediate memory, with results differing based on the measure of functioning used. Our findings suggest that there may be additional non-cognitive factors influencing this relationship and highlight the importance of using multiple methods to assess functional performance.