Combination of plasma amyloid beta(1-42/1-40) and glial fibrillary acidic protein strongly associates with cerebral amyloid pathology

Abstract

Background Blood-based biomarkers for Alzheimer’s disease (AD) might facilitate identification of participants for clinical trials targeting amyloid beta (Abeta) accumulation, and aid in AD diagnostics. We examined the potential of plasma markers Abeta(1-42/1-40), glial fibrillary acidic protein (GFAP) and neurofilament light (NfL) to identify cerebral amyloidosis and/or disease severity. Methods We included individuals with a positive (n = 176: 63 ± 7 years, 87 (49%) females) or negative (n = 76: 61 ± 9 years, 27 (36%) females) amyloid PET status, with syndrome diagnosis subjective cognitive decline (18 PET+, 25 PET−), mild cognitive impairment (26 PET+, 24 PET−), or AD-dementia (132 PET+). Plasma Abeta(1-42/1-40), GFAP, and NfL were measured by Simoa. We applied two-way ANOVA adjusted for age and sex to investigate the associations of the plasma markers with amyloid PET status and syndrome diagnosis; logistic regression analysis with Wald’s backward selection to identify an optimal panel that identifies amyloid PET positivity; age, sex, and education-adjusted linear regression analysis to investigate associations between the plasma markers and neuropsychological test performance; and Spearman’s correlation analysis to investigate associations between the plasma markers and medial temporal lobe atrophy (MTA). Results Abeta(1-42/1-40) and GFAP independently associated with amyloid PET status (p = 0.009 and p < 0.001 respectively), and GFAP and NfL independently associated with syndrome diagnosis (p = 0.001 and p = 0.048 respectively). The optimal panel identifying a positive amyloid status included Abeta(1-42/1-40) and GFAP, alongside age and APOE (AUC = 88% (95% CI 83–93%), 82% sensitivity, 86% specificity), while excluding NfL and sex. GFAP and NfL robustly associated with cognitive performance on global cognition and all major cognitive domains (GFAP: range standardized β (sβ) = − 0.40 to − 0.26; NfL: range sβ = − 0.35 to − 0.18; all: p < 0.002), whereas Abeta(1-42/1-40) associated with global cognition, memory, attention, and executive functioning (range sβ = 0.22 – 0.11; all: p < 0.05) but not language. GFAP and NfL showed moderate positive correlations with MTA (both: Spearman’s rho> 0.33, p < 0.001). Abeta(1-42/1-40) showed a moderate negative correlation with MTA (Spearman’s rho = − 0.24, p = 0.001). Discussion and conclusions Combination of plasma Abeta(1-42/1-40) and GFAP provides a valuable tool for the identification of amyloid PET status. Furthermore, plasma GFAP and NfL associate with various disease severity measures suggesting potential for disease monitoring.

Comparison of ELISA- and SIMOA-based quantification of plasma Aβ ratios for early detection of cerebral amyloidosis

“…Subsequently, the reconstituted calibrators were aliquoted in separate PP tubes (Qiagen, 19560) per ELISA plate and stored at − 20 °C until testing. SIMOA Amyblood assays were performed as described earlier [ 28 ], and in-house developed ready-to-use calibrators were employed, which were composed of the same recombinant proteins (rPeptide, Athens, USA) as the ELISA calibrators.…”

Targeting hippocampal hyperactivity with real-time fMRI neurofeedback: protocol of a single-blind randomized controlled trial in mild cognitive impairment

“…Likewise, we will include the BDNF genotype as it serves as a genetic modifier of brain plasticity and, thus, may influence the ability to learn from feedback. Finally, we will obtain Aβ42 as well as Aβ42/40 levels from blood using Simoa technology using methods established by the Neurochemistry Lab Amsterdam University Medical Centres [ 19 ]. Since hippocampal hyperactivity is particularly present in those with increased Aβ (and vice versa), the acquisition of Aβ is of specifal interest for this study.…”

Plasma Glial Fibrillary Acidic Protein Detects Alzheimer Pathology and Predicts Future Conversion to Alzheimer Dementia in Patients With Mild Cognitive Impairment

“…Glial brillary acidic protein (GFAP) is expressed in the cytoskeleton of astrocytes and has been found signi cantly increased in CSF in AD and other neurodegenerative diseases compared to healthy controls (12)(13)(14)(15). GFAP has also been recently measured in plasma and serum, where it was found increased in different neurological conditions, including AD (16)(17)(18)(19)(20)(21)(22)(23)(24). Increase of plasma GFAP in AD patients was associated to amyloid-PET positivity and worse outcomes in global cognition (22,24,25).…”

“…GFAP has also been recently measured in plasma and serum, where it was found increased in different neurological conditions, including AD (16)(17)(18)(19)(20)(21)(22)(23)(24). Increase of plasma GFAP in AD patients was associated to amyloid-PET positivity and worse outcomes in global cognition (22,24,25). Even though previous studies suggest that blood GFAP levels are elevated in AD and can identify an amyloid-PET positive status, no studies have been done investigating whether plasma GFAP can predict future conversion to AD dementia in patients with mild cognitive impairment (MCI).…”