NEFL and synucleinopathy: T-tau and UCHL-1 protein levels were lower in the iRBD and synucleinopathy groups compared to the control group.<h4>Conclusion</h4>Our findings suggest that serum levels of NfL, GFAP, t-tau, and UCH-L1 may serve as potential biomarkers in iRBD, primarily GFAP levels.