Circulating phosphatidylserine as a plasma biomarker for clinical staging and prognostic prediction in Parkinson's disease: A diagnostic validation study

Background Circulating phosphatidylserine (cPS) may reflect neuronal injury in Parkinson's disease (PD), yet its diagnostic and prognostic utility remains unvalidated. This study aimed to evaluate cPS as a plasma biomarker for PD staging and outcome prediction.Methods In this 24-month prospective cohort (STARD-compliant), 120 PD patients (40 early Hoehn and Yahr scale [H&Y] I-II, 40 moderate III, 40 advanced IV-V) and 40 matched controls were enrolled. cPS was quantified via ELISA. Disease severity was assessed by MDS-UPDRS-III and H&Y staging; outcomes included Barthel Index (BI≤40 defining poor prognosis) and cognitive decline (≥4-point Montreal Cognitive Assessment [MoCA] drop). Statistical analyses involved Spearman correlations, ROC curves, mixed-effects models, and multivariable regressions.Results Baseline cPS increased with PD severity (control: 35.2 ± 8.45 vs. advanced: 89.45 ± 15.20 ng/mL, P Conclusions cPS levels correlate with PD severity, predict functional and cognitive decline, and exhibit stage-specific longitudinal changes, supporting cPS as a candidate biomarker for PD monitoring, though further validation is required.