Background and purpose
The cerebrospinal fluid (CSF) concentration of α-synuclein may reflect the aggregation of α-synuclein in brain tissue that neuropathologically characterizes Parkinson's disease (PD). Although most studies in large cohorts report reduced CSF α-synuclein levels in PD, the available data to date are not consistent due to variation in group sizes, pre-analytical confounding factors and assay characteristics. Furthermore, it remains unclear whether CSF α-synuclein concentrations correlate with measures of disease severity. Acknowledging the methodological issues that emerged from previous studies, we evaluated whether CSF α-synuclein levels differ between patients with PD and controls, and relate to disease duration or severity.