Complex interactions underlie racial disparity in the risk of developing Alzheimer's disease dementia.

Introduction: We aim to determine racial disparities and their modifying factors in risk for Alzheimer's disease (AD) dementia among cognitively normal individuals 65 years or older.

Methods: Longitudinal data from the National Alzheimer's Coordinating Center Uniform Data Set on 1229 African Americans (AAs) and 6679 whites were analyzed for the risk of AD using competing risk models with death as a competing event.

Results: Major AD risk factors modified racial differences which, when statistically significant, occurred only with older age among APOE ε4 negative individuals, but also with younger age among APOE ε4 positive individuals. The racial differences favored AAs among individuals with body mass index (BMI) < 30, but whites among individuals with a high BMI (≥ 30), and were additionally modified by sex, education, hypertension, and smoking status.

Conclusions: The presence, direction, and relative magnitude of racial disparity for AD represent an interactive function of major AD and cerebrovascular risk factors.