Plasma biomarkers of neurodegeneration in mild cognitive impairment with Lewy bodies
Calum A. Hamilton, John T. O’Brien, Amanda Heslegrave, Rhiannon Laban, Paul C. Donaghy, Rory Durcan, Sarah Lawley, Nicola Barnett, Gemma Roberts, Michael Firbank, John‐Paul Taylor, Henrik Zetterberg, Alan Thomas
Abstract
Abstract Background Blood biomarkers of Alzheimer's disease (AD) may allow for the early detection of AD pathology in mild cognitive impairment (MCI) due to AD (MCI-AD) and as a co-pathology in MCI with Lewy bodies (MCI-LB). However not all cases of MCI-LB will feature AD pathology. Disease-general biomarkers of neurodegeneration, such as glial fibrillary acidic protein (GFAP) or neurofilament light (NfL), may therefore provide a useful supplement to AD biomarkers. We aimed to compare the relative utility of plasma A β 42/40, p -tau181, GFAP and NfL in differentiating MCI-AD and MCI-LB from cognitively healthy older adults, and from one another. Methods Plasma samples were analysed for 172 participants (31 healthy controls, 48 MCI-AD, 28 possible MCI-LB and 65 probable MCI-LB) at baseline, and a subset ( n = 55) who provided repeated samples after ≥1 year. Samples were analysed with a Simoa 4-plex assay for A β 42, A β 40, GFAP and NfL, and incorporated previously-collected p -tau181 from this same cohort. Results Probable MCI-LB had elevated GFAP ( p < 0.001) and NfL ( p = 0.012) relative to controls, but not significantly lower A β 42/40 ( p = 0.06). GFAP and p -tau181 were higher in MCI-AD than MCI-LB. GFAP discriminated all MCI subgroups, from controls (AUC of 0.75), but no plasma-based marker effectively differentiated MCI-AD from MCI-LB. NfL correlated with disease severity and increased with MCI progression over time ( p = 0.011). Conclusion Markers of AD and astrocytosis/neurodegeneration are elevated in MCI-LB. GFAP offered similar utility to p -tau181 in distinguishing MCI overall, and its subgroups, from healthy controls.