Paper
Strategies to establish a biologically defined Parkinson's disease cohort prior to the onset of clinically significant motor symptoms
Brown · 2026 · medrxiv
10.64898/2026.10.26.26366535Find this paper
Abstract
Identifying individuals at risk for neurodegeneration is a priority for clinical trials. Parkinson's Precision Medicine Initiative (PPMI) deploys strategies to enroll individuals before typical clinical Parkinson's disease symptoms: recruiting polysomnogram-confirmed REM sleep behavior disorder (RBD) and central identification of hyposmia via smell testing. Groups were divided into RBD with and without hyposmia (RBD+Hyposmia, RBD-Hyposmia) and hyposmia with and without self-reported dream enactment behavior (Hyposmia+DEB, Hyposmia-DEB). Participants underwent clinical and biomarker testing including CSF alpha-synuclein seed amplification assay (CSFaSynSAA) and dopamine transporter imaging. While all enrollment strategies showed robust enrichment for CSFaSynSAA positivity, RBD+Hyposmia and Hyposmia+DEB were more likely CSFaSynSAA+ (94% and 85%) vs RBD-Hyposmia (40%) and Hyposmia-DEB (55%). Among CSFaSynSAA+, RBD+Hyposmia and Hyposmia+DEB had more mood, autonomic, and cognitive symptoms than Hyposmia-DEB. PPMI identified a large biologically-defined early neuronal synucleinopathy cohort and demonstrated biomarker and multi-domain clinical heterogeneity within CSFaSynSAA+ individuals prior to symptom onset.
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