Promising Diagnostic Accuracy of Plasma GFAP and NfL Within The AD Continuum

Abstract

Background: Blood-based biomarkers may add a great benefit in detecting the earliest neuropathological changes in patients with Alzheimer’s disease (AD). We examined the utility of neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) in plasma and cerebrospinal fluid (CSF) regarding clinical diagnosis and amyloid positivity in an outpatient memory clinic - based cohort. Methods: In this retrospective analysis, we included a total of 185 patients, 141 patients along clinical the AD continuum, i.e. subjective cognitive decline (SCD, n=18), mild cognitive impairment (MCI, n=63), AD (n=60) and 44 age-matched healthy controls (HC). CSF and plasma concentrations of NfL and GFAP were measured with single molecule array (SIMOAâ) technology using the Neurology 2-Plex B kit from Quanterix. Amyloid-PET was performed in 75 patients and graded as amyloid positive and negative by visual rating. To assess the discriminatory potential of different biomarkers, age- and sex-adjusted receiver operating characteristic (ROC) curves were calculated and the area under the curve (AUC) of each model was compared using DeLong’s test for correlated AUC curves.Results: We constructed a panel combining plasma NfL and GFAP with known AD risk factors (age+sex+APOE4+GFAP+NfL panel). Using this panel, AUC was 91.6% for HC vs. AD, 81.7% for HC vs. MCI, 85% for SCD vs. AD, 81.3% for SCD vs. MCI, 77.7% for HC vs. SCD and 72.3% for MCI vs. AD. In terms of predicting amyloid PET status, we computed an AUC of 88.4%. Conclusion: The combination of plasma GFAP and NfL with well-established risk factors could contribute crucially to the identification of patients at risk, and thereby facilitate inclusion of patients in clinical trials for disease modifying therapies.

Serum glial fibrillary acidic protein and neurofilament light chain in patients with early treated phenylketonuria

“…None of the patients of our ETPKU cohort had symptoms indicative of advanced neurodegenerative disease. However, it has recently been shown for Alzheimer‘s disease that sGFAP is a promising biomarker to identify patients at-risk ( 42 , 57 ). Therefore, one could speculate that also in ETPKU, sGFAP might be a biomarker to identify patients at-risk for neurodegenerative disease, a hypothesis that needs further investigation in prospective studies.…”

“…In contrast to sGFAP that is promising in identifying patients at-risk for neurodegenerative disease such as Alzheimer‘s disease, sNfL as a biomarker detecting axonopathy is considered to be more helpful in discriminating later stages ( 42 , 57 ). On this basis, one could speculate that the normal sNfL levels in our ETPKU cohort, also in those patients with sGFAP concentrations above the HC range, are due to the absence of advanced, clinically relevant astrogliosis.…”

“…With the development of an ultrasensitive single molecule array (Simoa R ), GFAP and NfL have shown to be promising blood biomarkers for astrocytic response and neuroaxonal injury within the central nervous system in various neuroinflammatory and neurodegenerative disorders (37,41). As GFAP and NfL are indicative of ongoing neuroinflammatory and neurodegenerative disease processes, they are of great use in detecting earliest neuropathological changes and provide information about neuropathological progression (42)(43)(44)(45)(46).…”