There are persistent disparities in Alzheimer's disease by race and ethnicity that are not well understood. The emphasis given to seeking a genetic basis for racial differences might be a distraction from the more relevant issue of identifying preventable causes of Alzheimer's disease. The majority of Alzheimer's disease cases are diagnosed as the late onset type and are unlikely to be inherited. Late onset Alzheimer's disease cases, therefore, more likely represent variations in gene expression than gene frequency. Although conceptual and methodologic problems have limited our understanding of this relationship, race-based studies provide important opportunities to understand the environmental factors associated with gene expression. Improving our understanding of the factors associated with race and ethnicity might help to clarify the epidemiology and course of Alzheimer's disease.