<h3>Importance</h3> We observed a significant correlation between cerebrospinal fluid (CSF) levels of tau proteins and α-synuclein, but not β-amyloid 1-42 (Aβ1-42), and lower concentration of CSF biomarkers, as compared with healthy controls, in a cohort of entirely untreated patients with Parkinson disease (PD) at the earliest stage of the disease studied so far. <h3>Objective</h3> To evaluate the baseline characteristics and relationship to clinical features of CSF biomarkers (Aβ1-42, total tau [T-tau], tau phosphorylated at threonine 181 [P-tau<sub>181</sub>], and α-synuclein) in drug-naive patients with early PD and demographically matched healthy controls enrolled in the Parkinson’s Progression Markers Initiative (PPMI) study. <h3>Design, Setting, and Participants</h3> Cross-sectional study of the initial 102 research volunteers (63 patients with PD and 39 healthy controls) of the PPMI cohort. <h3>Main Outcomes and Measures</h3> The CSF biomarkers were measured by INNO-BIA AlzBio3 immunoassay (Aβ1-42, T-tau, and P-tau<sub>181</sub>; Innogenetics Inc) or by enzyme-linked immunosorbent assay (α-synuclein). Clinical features including diagnosis, demographic characteristics, motor, neuropsychiatric, and cognitive assessments, and DaTscan were systematically assessed according to the PPMI study protocol. <h3>Results</h3> Slightly, but significantly, lower levels of Aβ1-42, T-tau, P-tau<sub>181</sub>, α-synuclein, and T-tau/Aβ1-42 were seen in subjects with PD compared with healthy controls but with a marked overlap between groups. Using multivariate regression analysis, we found that lower Aβ1-42 and P-tau<sub>181</sub>levels were associated with PD diagnosis and that decreased CSF T-tau and α-synuclein were associated with increased motor severity. Notably, when we classified patients with PD by their motor phenotypes, lower CSF Aβ1-42 and P-tau<sub>181</sub>concentrations were associated with the postural instability–gait disturbance–dominant phenotype but not with the tremor-dominant or intermediate phenotype. Finally, we found a significant correlation of the levels of α-synuclein with the levels of T-tau and P-tau<sub>181</sub>. <h3>Conclusions and Relevance</h3> In this first report of CSF biomarkers in PPMI study subjects, we found that measures of CSF Aβ1-42, T-tau, P-tau<sub>181</sub>, and α-synuclein have prognostic and diagnostic potential in early-stage PD. Further investigations using the entire PPMI cohort will test the predictive performance of CSF biomarkers for PD progression.

Association of Cerebrospinal Fluid β-Amyloid 1-42, T-tau, P-tau<sub>181</sub>, and α-Synuclein Levels With Clinical Features of Drug-Naive Patients With Early Parkinson Disease

Association of Cerebrospinal Fluid β-Amyloid 1-42, T-tau, P-tau181, and α-Synuclein Levels With Clinical Features of Drug-Naive Patients With Early Parkinson Disease