Cerebrospinal Fluid Total and Phosphorylated α-Synuclein in Patients with Creutzfeldt-Jakob Disease and Synucleinopathy.

High levels of total α-synuclein (t-α-synuclein) in the cerebrospinal fluid (CSF) were reported in sporadic Creutzfeldt-Jakob disease (sCJD). The potential use of t-α-synuclein in the discrimination of Lewy body dementias (i.e., Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB)) is still under investigation. In addition, phospho-serine-129 α-synuclein (p-α-synuclein) has been described to be slightly increased in the CSF of synucleinopathies. Here, we analyzed t-α-synuclein and p-α-synuclein concentrations and their ratio in the context of differential diagnosis of neurodegenerative diseases. We quantified the levels of CSF t-α-synuclein and p-α-synuclein in a cohort of samples composed of neurological controls (NC), sCJD, PDD, and DLB by means of newly developed specific enzyme-linked immunosorbent assays. T-α-synuclein and p-α-synuclein were specifically elevated in sCJD compared to other disease groups. The area under the curve (AUC) values for t-α-synuclein were higher for the discrimination of sCJD from dementias associated to Lewy bodies as compared to the use of p-α-synuclein. A combination of both markers even increased the diagnostic accuracy. An inverse correlation was observed in CSF between t-α-synuclein and p-α-synuclein, especially in the DLB group, indicating a disease-relevant association between both markers. In conclusion, our data confirm t-α-synuclein and p-α-synuclein as robust biomarkers for sCJD and indicate the potential use of colorimetric t-α-synuclein ELISAs for differential diagnosis of dementia types.