SUMMARY
# Alpha-Synuclein SAA Kinetics Study — Biological Staging Backbone for PD Progression
## Background and Rationale
Parkinson's disease (PD) clinical staging currently relies on motor symptom progression, which poorly reflects underlying biological heterogeneity and limits precision therapeutic approaches. Accumulating evidence suggests that alpha-synuclein (α-syn) pathological species exhibit distinct seeding and propagation kinetics that may define biologically meaningful disease subtypes. This
METHODOLOGY NOTES
Phase 1 (Months 0-6): Recruit 200 early PD patients (Hoehn-Yahr 1-2, <3 years since diagnosis), 100 prodromal subjects (REM sleep behavior disorder with abnormal DaTscan), and 100 age-matched healthy controls. Obtain baseline lumbar punctures for CSF collection (15mL), comprehensive clinical assessments (MDS-UPDRS, Montreal Cognitive Assessment), and DaTscan imaging. Phase 2 (Months 0-36): Perform α-syn SAA using recombinant α-syn fibrils as seeds with CSF samples in quadruplicate using thioflavin-T fluorescence monitoring every 15 minutes for 100 hours. Extract kinetic parameters: lag time (hours to 10% maximum fluorescence), growth rate (slope of exponential phase), and maximum amplitude. Simultaneously measure CSF neurofilament light, total tau, and phospho-tau181 by ultrasensitive immunoassays. Phase 3 (Months 6, 12, 24, 36): Conduct longitudinal follow-up visits with clinical assessments, repeat neuroimaging at 18 and 36 months, and optional repeat lumbar punctures at 18 and 36 mo