Diagnostic and prognostic performance of CSF α‐synuclein in prion disease in the context of rapidly progressive dementia

INTRODUCTION: Surrogate cerebrospinal fluid (CSF) biomarkers of neurodegeneration still have a central role in the first‐line screening of patients with suspected Creutzfeldt‐Jakob disease (CJD). Recently, CSF α‐synuclein, a marker of synaptic damage, showed a close to optimal performance in distinguishing between CJD and other neurodegenerative dementias. METHODS: We evaluated the diagnostic value of CSF α‐synuclein in patients with prion disease, non‐prion rapidly progressive dementias, and non‐neurodegenerative controls. Additionally, we studied its distribution across the different prion disease subtypes and evaluated its association with survival. RESULTS: CSF α‐synuclein levels were significantly higher in patients with prion disease than in the other groups but showed a lower diagnostic value than CSF total tau or 14‐3‐3. Moreover, CSF α‐synuclein was significantly associated with survival in the whole prion cohort and the most frequent clinicopathological subtypes. DISCUSSION: In the clinical setting, CSF α‐synuclein does not exceed the diagnostic performance of currently used surrogate markers, but it might constitute a robust prognostic indicator.