Traumatic brain injury history is associated with earlier age of onset of Alzheimer disease

AbstractObjective: This study examined whether a history of traumatic brain injury (TBI) is associated with earlier onset of Alzheimer disease (AD), independent of apolipoprotein e4 status (Apoe4) and gender.Method: Participants with a clinical diagnosis of AD (n = 7625) were obtained from the National Alzheimer’s Coordinating Center Uniform Data Set, and categorized based on self-reported lifetime TBI with loss of consciousness (LOC) (TBI+ vs. TBI−) and presence of Apoe4. ANCOVAs, controlling for gender, race, and education were used to examine the association between history of TBI, presence of Apoe4, and an interaction of both risk factors on estimated age of AD onset.Results: Estimated AD onset differed by TBI history and Apoe4 independently (p’s < .001). The TBI+ group had a mean age of onset 2.5 years earlier than the TBI− group. Likewise, Apoe4 carriers had a mean age of onset 2.3 years earlier than non-carriers. While the interaction was non-significant (p = .34), participants having both a histor...