Abstract

Objective: Traumatic brain injury (TBI) has been identified as a risk factor for Alzheimer's disease (AD), but the relationship to Mild Cognitive Impairment (MCI), a prodromal stage of AD, is unknown. This study examined whether a history of TBI without chronic deficits leads to an earlier age of MCI diagnosis in a large national cohort. Method: MCI subjects were obtained from the National Alzheimer's Coordinating Center Uniform Data Set database. Subjects were categorized based on lifetime reported TBI with <5 minutes loss of consciousness (mLOC; n = 214) or >5 mLOC (n = 104) and compared in terms of age at diagnosis (DxAge) to MCI subjects without TBI (n = 3090) using ANOVA. Results: Age, education, and race were similar across groups, although the TBI sample contained more males (58%) compared to those without TBI (45% male). Subjects with a history of self-reported TBI <5 mLOC (M DxAge = 73.5, SD = 10.8) and > 5 mLOC (M DxAge = 72.0, SD = 9.6) were diagnosed with MCI an average of 2.5 years earlier than those without TBI (M DxAge = 76.1, SD = 10.2; p < .0001), even when controlling for gender. Conclusion(s): A history of TBI was associated with a 2.5 year earlier diagnosis of MCI compared to those without TBI. This parallels findings in AD and supports emerging literature of TBI as a risk factor for cognitive decline later in life.