We found that 8% of the disparity in prevalent dementia between non-Hispanic Black and non-Hispanic White participants was due to the interaction between race and high cystatin C levels, while 2% was mediated through cystatin C. Altogether, these results suggest that, among older adults who are racialized as non-Hispanic Black or Hispanic, the effect of high cystatin C levels on dementia prevalence is greater than expected had these individuals been racialized and treated as non-Hispanic White (Phelan and Link, 2015; Asad, 2018; Graetz et al., 2022). The gene discussed is CST3; the disease is dementia.