APOE and Alzheimer disease: The median concentration of CSF Klotho was significantly higher in the control group (β = 0.103; 95% CI, 0.023-0.183; P = .01) and AD-MCI group (β = 0.095; 95% CI, 0.018-0.172; P = .02) compared with the AD-dementia group, using multivariable linear regression adjusting for age, sex, KL-VS heterozygosity, and APOE4 status.