Plasma Phosphorylated Tau181 and Amyloid-β42 in Dementia with Lewy Bodies Compared with Alzheimer’s Disease and Cognitively Healthy People

Background: Increasing evidence illustrates the value of plasma biomarkers of Alzheimer’s disease (AD) to screen for and identify dementia with Lewy bodies (DLB). However, confirmatory studies are needed to demonstrate the feasibility of these markers. Objective: To determine the feasibility of plasma tau phosphorylated at threonine 181 (p-tau181) and amyloid-β 42 (Aβ 42 ) as potential biomarkers to differentiate AD and DLB. Methods: We evaluated plasma samples from patients with DLB ( n = 47) and AD ( n = 55) and healthy controls (HCs, n = 30), using ELISAs to measure p-tau181 and Aβ 42 . Additionally, we examined neuropsychological assessment scores for participants. The plasma biomarkers were investigated for correlation with neuropsychological assessments and discriminant ability to identify DLB. Results: Plasma p-tau181 was significantly lower in DLB than in AD and HCs. Plasma Aβ 42 was significantly higher in DLB than in AD but lower in DLB than in HCs. We found good correlations between plasma Aβ 42 and neuropsychological scores in the whole cohort, while p-tau181 was associated with cognitive status in DLB. In the distinction between DLB and HCs, plasma p-tau181 and Aβ 42 showed similar accuracy, while Aβ 42 showed better accuracy than p-tau181 in discriminating DLB and AD. Conclusion: In a single-center clinical cohort, we confirmed the high diagnostic value of plasma p-tau181 and Aβ 42 for distinguishing patients with DLB from HCs. Plasma Aβ 42 improved the differential diagnosis of DLB from AD.