Chronic kidney disease and blood‐based biomarkers of Alzheimer's disease: the brain in kidney disease study
Kerry M. Sheets, Joseph M. Curran, Michelle M. Mielke, Xuemei Zeng, Thomas K. Karikari, Courtney L. Sutphen, Thomas C. Register, Anne M. MurrayAbstract
BACKGROUND
Reduced kidney function affects the levels of many Alzheimer's disease and related dementias (ADRD) blood‐based biomarkers (BBMs). The extent to which kidney function is associated with serum levels of brain‐derived tau (BD‐tau), a novel BBM specific for Alzheimer's disease‐type neurodegeneration, is unknown.
METHODS
ADRD BBMs were measured in stored serum samples from 443 BRain IN Kidney Disease study participants (mean age 68.9 years, 49% female).
RESULTS
Lower estimated glomerular filtration rate (eGFR; poorer kidney function) was inversely associated with levels of serum BD‐tau: BD‐tau 54.6 pg/mL (standard deviation [SD] 24.47) for eGFR < 15 mL/min/1.73 m 2 , 34.16 [20.47] for eGFR 15 to 29, 22.89 [23.43] for eGFR 30 to 44, 16.76 [19.88] for eGFR 45 to 59, and 9.19 [9.05] for eGFR ≥60. Greater urine albumin‐to‐creatinine ratio (UACR; greater albuminuria) was positively associated with levels of serum BD‐tau: BD‐tau 39.84 pg/mL [SD 31.76] for UACR > 300 mg/g, 22.57 [21.59] for UACR 30 to 300, and 14 [10.72] for UACR < 30. These trends were consistent for all levels of cognitive impairment (CI; from no CI to severe CI) and persisted following adjustment for age, race, sex, and education. In contrast, associations of kidney function with the pTau217/BD‐tau ratio were generally non‐significant.
DISCUSSION
Kidney function needs to be considered when interpreting BD‐tau levels.