CSF biomarkers β-amyloid, tau proteins and a-synuclein in the differential diagnosis of Parkinson-plus syndromes

Abstract

IntroductionDifferential diagnosis of Parkinson-plus patients (PSP, CBD, MSA) and Parkinson's disease (PD) patients is often not straightforward, particularly in atypical cases or at the initial stages of the diseases. Classic CSF biomarkers (amyloid-beta – Aβ42, tau protein – τT and phosphorylated tau protein – τP-181) are established biomarkers in the diagnosis of Alzheimer's disease (AD). CSF a-synuclein (α-syn) has emerged as a promising biomarker in patients with Parkinsonism. The aim of this study was to analyze the CSF biochemical profile of patients with Parkinsonism. MethodsWe analyzed the CSF biomarker profile (Aβ42, τT, τP-181, α-syn) and all relevant ratios in 68 patients with Parkinsonism (19 PSP, 15 MSA, 17 CBD, 17 PD) and 18 controls, diagnosed by latest established diagnostic criteria. ResultsCBD patients exhibited elevated τT and decreased Aβ42 compared to the other groups. Five CBD, one PSP patient and one control had a typical AD CSF profile. After exclusion of these patients, the τT/Aβ42 ratio was significantly elevated in MSA patients compared to PD patients and provided excellent specificity and adequate sensitivity in their differential diagnosis. ConclusionCSF biochemical profile analysis is important in distinguishing AD patients with a CBS phenotype from non-AD CBS patients. The τT/Aβ42 ratio is useful in the differential diagnosis of MSA from PD.