Estimating prevalence of early Alzheimer's disease in the United States, accounting for racial and ethnic diversity.

Introduction: Updated estimates of the US Alzheimer's disease (AD) population, including under-represented populations, are needed to improve clinical trial diversity.

Methods: A step-wise approach calculating prevalent numbers from clinical syndrome to biomarker-positive mild cognitive impairment (MCI) due to AD and mild AD was developed, using age-and-race/ethnicity-stratified data where available.

Results: The estimated percentage of Americans aged ≥ 65 years with MCI due to AD was 9.2% of non-Hispanic Whites, 13.6% of non-Hispanic Blacks, 11.1% Hispanics, and 9.7% other race/ethnicities. The estimated percentage of Americans aged ≥ 65 years with mild dementia due to AD among non-Hispanic Whites was 3.7%, non-Hispanic Blacks 7.0%, Hispanics 5.3%, and 3.9% other race/ethnicities. Of these early-stage AD cases, few are likely diagnosed, ranging from 13% of prevalent non-Hispanic Black cases to 27% of non-Hispanic White cases.

Discussion: Under-representation in clinical trials may be improved by setting recruitment goals reflecting the diversity of the AD patient population and supporting efforts toward timely diagnosis.