Blood-based biomarkers for Alzheimer’s disease: influence of kidney function

Research overview

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Abstract Background Blood biomarkers may aid Alzheimer’s disease (AD) diagnosis; however, their reliability can be affected by systemic conditions such as kidney dysfunction (KD). We evaluated the impact of KD on plasma levels of amyloid-β (Aβ42/Aβ40), phosphorylated tau (p-Tau181, p-Tau217), and neurofilament light chain (NfL), and developed correction strategies. Methods We retrospectively selected 112 individuals (52 with AD, 21 with other neurodegenerative diseases, and 39 with non-neurodegenerative conditions) who had a previously documented abnormal renal function value. Participants were included based on the availability of: i)previously measured cerebrospinal fluid (CSF) Aβ42/Aβ40, p-Tau181, and NfL; ii) plasma samples for the measurement of Aβ42/Aβ40, p-Tau217, p-Tau181, and NfL; iii) paired serum samples collected at the same time to re-measure creatinine and ensure temporal correspondence between kidney function and biomarker assessments. Plasma biomarkers were quantified using the Lumipulse G1200 platform. Kidney dysfunction (KD) was defined as eGFR Results KD was present in 51.8% of patients and associated with increased plasma levels of Aβ42, Aβ40, p-Tau181, p-Tau217, and NfL, not with the Aβ42/Aβ40 ratio. Creatinine-based correction improved the correlation between plasma and CSF NfL and enhanced the diagnostic performance of plasma p-Tau181 and p-Tau217 for AD. Corrected cut-offs aligned with those from KD-free cohorts. Conclusions KD alters plasma biomarker concentrations. Creatinine-based normalization in patients with KD may allow to rely on cut-offs generated on cohorts without KD. Funding: Italian Ministry of Health; Italian Research Association on Alzheimer’s Disease (AirAlzh); Parkinson’s Foundation.

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