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 e4 (APOE e4) 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 e4 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 e4 alleles, or cognitive diagnosis (p's > .001).Conclusions: Findings suggest TBI history, regardless of demographic factors, APOE e4 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.