Elevated Levels of α-Synuclein Oligomer in the Cerebrospinal Fluid of Drug-Naïve Patients with Parkinson's Disease

BACKGROUND AND PURPOSE The detection of α-synuclein in the body fluids of patients with synucleinopathy has yielded promising but inconclusive results, in part because of conformational changes of α-synuclein in response to environmental conditions. The aim of this study was to determine the feasibility of using α-synuclein as a biological marker for Parkinson's disease (PD). METHODS Twenty-three drug-naïve patients with PD (age 62.4±12.7 years, mean±SD; 11 males) and 29 age- and sex-matched neurologic control subjects (age 60.1±16.2 years; 16 males) were recruited. The levels of oligomeric and total α-synuclein in the cerebrospinal fluid (CSF) and plasma were measured using two simultaneous enzyme-linked immunosorbent assays. RESULTS The level of α-synuclein oligomer in the CSF of PD patients was significantly higher in PD patients than in neurological controls, but other findings (plasma α-synuclein oligomer and total α-synuclein in CSF and plasma) did not differ significantly between the two groups. When the control subjects were divided into a symptomatic control group (11 patients who complained of parkinsonian symptoms and were diagnosed with hydrocephalus and drug-induced or vascular parkinsonism) and a neurologic control group (10 normal subjects and 8 patients with diabetic ophthalmoplegia), the level of α-synuclein oligomer in the CSF was still significantly higher in PD patients than in both of the control subgroups. CONCLUSIONS These findings provide further evidence for a pathogenic role of the α-synuclein oligomer and suggest that CSF levels of α-synuclein oligomer can be a reliable marker for PD.