Plasma Neurofilament Light Chain and TNF-α Correlate with Motor Features in Isolated REM Sleep Behavior Disorder

Isolated RBD (iRBD) is a prominent early marker of Parkinson's disease and related disorders.

Evaluate biomarkers of inflammation and axonal damage people with iRBD for disease progression.

Plasma samples from 27 video-polysomnography confirmed iRBD patients and 25 controls were analyzed for inflammatory biomarkers (CRP, IL-6, TNF-α, IFN-γ, IL-1β) and NfL using the Meso Scale Discovery platform.

People with iRBD had elevated plasma TNF-α and IL-6 (p = 0.013 and p = 0.051). In the iRBD group, plasma NfL was associated with objective motor tests: Timed Up and Go (R² = 0.292, p = 0.027) and 10-m walk (R² = 0.355, p = 0.034) and plasma TNF-α was associated with the Timed Up and Go test (R² = 0.277, p = 0.025).

We report evidence of peripheral inflammation in early synuclein-related disease processes, and association of plasma NfL and TNF-α with motor dysfunction in iRBD patients, suggesting possible association with increased risk of phenoconversion.