Fig 1: Antibodies to disease relevant proteins and serum markers in a stratified cohort of patients with RBD, early Parkinson’s disease and controls. (A) Serum and clinical assessments obtained from a stratified RBD cohort (high risk of conversion to Parkinson’s disease versus low risk) as well as early Parkinson’s disease and healthy controls. Risk of conversion to Parkinson’s disease was stratified using a standard scoring system including environmental risk (e.g. pesticide exposure), age and clinical parameters (motor and non-motor symptoms).31 Figures displayed as mean (standard deviation). (B) Antibodies to alpha-synuclein fibrils [ANCOVA F(5,162) = 4.275, P < 0.001 with post hoc t-tests with Bonferroni correction showing: high risk versus control P = 0.002, high risk versus low risk P = 0.002, high risk versus Parkinson’s disease, P = 0.003]. (C) IgG overall [ANCOVA, F(5,149] = 11.41, P < 0.001 with post hoc Bonferroni testing showing P = 0.001 for control versus low-risk and high-risk and for Parkinson’s disease versus low risk and high risk]. (D) Antibodies to alpha-synuclein. (E) antibodies to S129D peptide [ANCOVA F(5,139) = 3.14, P = 0.01, post hoc Bonferroni (low risk versus control, P = 0.005; low risk versus Parkinson’s disease, P = 0.004; low risk versus high risk, P = 0.05 (ns)]. (F) Antibodies to Y39 peptide of a synuclein. (G) Antibodies to tau. (H) CRP levels across the groups. (I) BAFF levels across the groups. RBD, REM sleep behaviour disorder; PD, Parkinson’s disease; BAFF, B-cell-activating factor; CRP, C reactive protein. One-way ANCOVA was performed to assess between-group differences in means. Differences displayed are those shown on post hoc testing. *P < 0.05 and **P < 0.001 indicate statistical significance compared to Parkinson’s disease and control groups after Bonferroni adjustment.