A-99 Influence of TBI on Rate of Cognitive Decline in Clinically Normal Older Adults

Objective History of traumatic brain injury (TBI) is a potential risk factor for cognitive decline and neurodegenerative disease later in life, but findings have been inconsistent. We evaluate if past history of TBI affects rate of cognitive decline in clinically normal older adults. Method Participants were 190 cognitively normal (CDR < 0.5) older adults (age at baseline: M = 71.6, SD = 7.0) with positive history of TBI (TBI+; n = 83) or no history of TBI (TBI-; n = 107). A comprehensive neuropsychological battery of attention, memory, language, and executive functioning measures as well as functional questionnaires were administered longitudinally (number of visits: M = 3.4, SD = 1.3). Linear mixed effects models assessed the interaction between longitudinal health outcomes and TBI history. Results TBI+ showed a faster rate of decline in executive functioning (Stroop interference: p = 0.04), and a faster increase in functional impairment (Physical Activity Scale for the Elderly (PASE) total: p < 0.001; Unified Parkinson’s Disease Rating Scale (UPDRS) total: p = 0.002). Baseline performance on these tests did not distinguish TBI+ from TBI- (Stroop interference, p = 0.4; PASE, p = 0.5; and UPDRS, p = 0.1). TBI+ was not significantly different from TBI- on measures in other cognitive domains. Conclusions History of TBI was associated with faster rate of executive functioning decline and more rapid increase in objective and subjective functional impairment in cognitively normal older adults. Findings suggest that sustaining a TBI earlier in life could accelerate cognitive and functional changes even among clinically normal older adults.