COMPARISONS OF THE INCIDENCE AND RISK FACTORS FOR DEVELOPING ADRD IN A NATIONAL SAMPLE OF OLDER WHITE AND AFRICAN AMERICAN VETERANS

This study compares racial differences in the incidence and risk factors for developing Alzheimer's Disease and Related Dementia (ADRD) in the US Veteran Health Administration (VHA). The study population included White Americans (WAs) and African Americans (AAs) aged 65+ years old who received service in the VHA between 1999 and 2016. The observations began at the index encounter until the occurrence of ADRD, death, loss to follow-up, or 12/31/2018, which occurred first. The index encounter was defined as the first time point when a veteran aged 65+ years old either had a hospitalization or 2 office visits within a 12-months period. All veterans were free of ADRD at study entry. We calculated ADRD incidence by age categories for each race, and conducted multivariate Cox models on the overall sample and race strata separately, to identify risk factors. 466,292 AAs and 3,769,589 WAs were included. Compared to WAs, AAs were younger, less likely to be married and to live in rural areas, and had more medical comorbidities. ADRD incidence increased by age category, ranging from 5.29 in 65–70 years old to 45.78 in 85+ years old per 10,000 person-months in AAs and 3.24 to 24.22 per 10,000 person-months in WAs. Overall, AAs had higher risk of developing ADRD than WAs (adjusted HR=1.64, 95%CI=1.62-1.66). Other significant risk factors included being Hispanics and not married, live in urban areas, and having medical comorbidities (including depression, stroke, and traumatic brain injury [TBI]). Several comorbid conditions were associated with reduced risk, including hypertension, hyperlipidemia, arthritis, and asthma. There was a significant interaction between gender and income with race, as AA women had a lower risk of ADRD but WA women had a higher risk; income level was associated with reduced risk of ADRD in WAs but not in AAs. This study included the largest cohort of US veterans aged 65+ with AAs had consistently higher risk for developing ADRD compared to WAs, regardless of age. Among risk factors, stroke and TBI had the strongest associations with ADRD. Further investigations are necessary to understand the risk and protective effects of these factors.