A-010 Traumatic Brain Injury, APOE, and Age at Diagnosis of Alzheimer’s Disease

Abstract

Abstract Objective Traumatic brain injury (TBI) is potentially a risk factor for Alzheimer’s disease (AD). This relationship may depend on the severity of TBI as well as other risk factors including APOE. We examined whether TBI status affects age of onset of AD, while improving on prior literature’s methodological issues. Method Data from the National Alzheimer’s Coordinating Centers were used. Inclusion criteria included: normal cognition at baseline; eventual diagnosis of AD; adults aged 50 and older; at least 3 years of follow-up data. Covariates included age at baseline and history of TIA, stroke, or hypertension. The resulting sample (N = 485) was 65.2% female; 89.1% White, 9.1% Black; and 4.5% Hispanic; 8% with TBI; and 42% with APOE4. Average age at baseline was 79.2 (SD = 7.6). ANCOVAs were used to determine whether TBI status (no TBI; TBI with brief LOC; TBI with extended LOC) was associated with earlier age of diagnosis for AD, controlling for age at baseline and health factors. APOE status was added to a second ANCOVA. Results Age at baseline (p < .001), but not health history (p = .777), was related to age of AD diagnosis. TBI status was not associated with age of AD diagnosis (p = .737). When APOE and the interaction between APOE and TBI status were added to the model, neither was significant (p’s = .150, .647). Conclusions When controlling for baseline cognition, age at baseline, and health factors, there was no relationship between TBI status and age of diagnosis of AD. However, use of more stringent inclusion criteria as compared to previous studies may have reduced power significantly.