Our sensitivity models suggest that the association between elevated circulating levels of cystatin C and the prevalence of dementia among non-Hispanic Black and Hispanic adults was independent of APOE-ε4 allele carrier status, since non-Hispanic Black and Hispanic participants with elevated cystatin C levels had higher prevalence of dementia than their non-Hispanic White counterparts after adjustment by APOE-ε4 allele carrier status. Here, APOE is linked to dementia.