History of Traumatic Brain Injury Does Not Alter Course of Neurocognitive Decline in Older Adults With and Without Cognitive Impairment

Objective: Traumatic brain injury (TBI) history is associated with dementia risk, but it is unclear whether TBI history significantly hastens neurocognitive decline in older adults. Method: Data were derived from the National Alzheimer’s Coordinating Center (NACC) data set. Participants with a history of TBI (TBI+; n = 1, 467) were matched to individuals without a history of TBI (TBI−; n = 1, 467) based on age (50–97, M = 71.61, SD = 8.40), sex, education, race, ethnicity, cognitive diagnosis, functional decline, number of Apolipoprotein ε4 (APOE ε4) alleles, and number of annual visits (3–6). Mixed linear models were used to assess longitudinal neuropsychological test composite scores of executive functioning/attention/speed, language, and memory in TBI+ and TBI− participants. Interactions between TBI and demographics, APOE ε4 status, and cognitive diagnosis were also examined. Results: Longitudinal neuropsychological functioning did not differ between TBI groups (p’s >.001). There was a significant three-way interaction (age, TBI history, time) in language (F[20, 5750.1] = 3.133, p <.001) and memory performance (F[20, 6580.8] = 3.386, p <.001), but post hoc analyses revealed TBI history was not driving this relationship (all p’s >.096). No significant interactions were observed between TBI history and sex, education, race/ethnicity, number of APOE ε4 alleles, or cognitive diagnosis (p’s >.001). Conclusions: Findings suggest TBI history, regardless of demographic factors, APOE ε4 status, or cognitive diagnosis, does not alter the course of neurocognitive functioning later-in-life in older adults with or without cognitive impairment. Future clinicopathological longitudinal studies that well-characterize head injuries and the associated clinical course are needed to help clarify the mechanism in which TBI may increase dementia risk.