Background Higher incidence levels of Alzheimer’s disease (AD) in Black Americans are well documented. However, quantitative explanations of this disparity in terms of risk-factor diseases acting through well-defined pathways is lacking. Methods We applied a Blinder-Oaxaca-based algorithm modified for censored data to a 5% random sample of Medicare beneficiaries age 65+ to explain Black/White disparities in AD risk in terms of differences in exposure and vulnerability to morbidity profiles based on 10 major AD-risk-related diseases. Results The primary contribution to racial disparities in AD risk comes from morbidity profiles that included hypertension with about 1/5 th of their contribution due to differences in prevalence (exposure effect) and 4/5 ths to differences in the effects of the morbidity profile on AD risk (vulnerability effect). In total, disease-related effects explained a higher proportion of AD incidence in Black Americans than in their White counterparts. Conclusions Disease-related causes may represent some of the most straightforward targets for targeted interventions aimed at the reduction of racial disparities in health among U.S. older adults. Hypertension is a manageable and potentially preventable condition responsible for the majority of the Black/White differences in AD risk, making mitigation of the role of this disease in engendering higher AD incidence in Black Americans a prominent concern.