The relationship between plasma biomarkers and amyloid PET in dementia with Lewy bodies

Introduction: Amyloid-beta (A beta) deposition is common in dementia with Lewy bodies (DLB) and has been associated with more rapid disease progression. An effective biomarker that identified the presence of significant brain A beta in people with DLB may be useful to identify and stratify participants for research studies and to inform prognosis in clinical practice. Plasma biomarkers are emerging as candidates to fulfil this role. Methods: Thirty-two participants with DLB had brain amyloid (18F-florbetapir) PET, of whom 27 also had an MRI to enable the calculation of 18F-florbetapir SUVR. Plasma A beta 42/40, phosphorylated tau (p-tau181), glial fibrillary acidic protein (GFAP) and neurofilament light (NfL) were measured using single molecule array (Simoa). The plasma biomarkers were investigated for correlation with 18F-florbetapir SUVR, discriminant ability to identify A beta-positive cases based on a predefined SUVR threshold of 1.10 and correlation with subse-quent cognitive decline over one year. Results: All four plasma markers significantly correlated with 18F-florbetapir SUVR (|beta| = 0.40-0.49; p < .05). NfL had the greatest area under the receiver operating characteristic curve to identify A beta-positive cases (AUROC 0.84 (95% CI 0.66, 1); beta = 0.46, p = .001), whereas A beta 42/40 had the smallest (AUROC 0.73 (95% CI 0.52, 0.95); beta = -0.47, p = .01). Accuracy was highest when combining all four biomarkers (AUROC 0.92 (95% CI 0.80, 1)). Lower plasma A beta 42/40 was significantly associated with more rapid decline in cognition (beta = 0.53, p < .01). Conclusions: Plasma biomarkers have the potential to identify A beta deposition in DLB. Further work in other co-horts is required to determine and validate optimal cut-offs for these biomarkers.

Automated summary

Plasma biomarkers are correlated with A beta deposition in DLB and can be used to identify A beta-positive cases and predict the rate of cognitive decline.