Kidney Function Impacts Plasma Alzheimer’s Biomarkers in a Cognitively Normal Multi- Ethnic Cohort

Background: Plasma biomarkers of Alzheimer’s disease (AD) can be cost-effective, non-invasive, scalable measures for screening into clinical research and trials. Little research has examined the impact of medical comorbidities on these biomarkers especially among underserved communities. The current study examined the impact of kidney functioning on plasma AD biomarkers among a multi-ethnic cohort. Methods: 1,328 cognitively unimpaired Mexican American (659) and non-Hispanic white (669) were examined. eGFR levels were categorized into eGFR1>=90 (normal kidney function), eGFR2 60-89 (mild kidney function loss) and eGFR3 <60 (moderate to severe kidney function loss). Aβ40, Aβ42, total tau and NfL were assayed using Simoa. Results: Mild and moderate/severe eGFR levels,were associated with all plasma biomarkers. For Mexican Americans, mild kidney and moderate/severe kidney function loss were associated with Aβ 40 , Aβ 42 , total tau and NfL. Among non-Hispanic whites, mild kidney function loss was associated with Aβ 40 and Aβ 42 whereas moderate/severe kidney function loss was associated with all biomarkers. Conclusions: Among cognitively normal adults, even mild kidney loss is associated with alterations in the plasma AD biomarkers. Additional work to determine how to best consider eGFR levels to avoid misdiagnosis and inappropriate referrals for more invasive, and costly, procedures based on plasma biomarker findings is needed.