In a subset of the study population (N = 251), we found incident MCI/AD had a faster decline (b = −0.048 [95% CI: −0.080, −0.016], P = 0.003) in PCA2 compared to CU after adjusting for Model 2 covariates (age, sex, ethnic group, education, APOE status, and comorbidities) as well as creatinine and BMI. Here, APOE is linked to Alzheimer disease.