Purpose of Review
To evaluate whether CSF and circulating neurofilament light chain (NfL), a marker of axonal damage, could discriminate Parkinson disease (PD) from atypical parkinsonian syndromes (APSs).
MEDLINE and Scopus were systematically searched, and 15 studies were included (1,035 patients with PD and 930 patients with APS). CSF NfL levels were 1.26 SDs higher in the APS group compared to the PD group (g = 1.26 [95% confidence interval 0.99–1.53]), and circulating NfL levels were 1.53 SDs higher in the APS group compared to the PD group (g = 1.53 [95% confidence interval 1.15–1.91]); 4 studies, 307 patients with PD, 197 patients with APS. Pooled areas under the curve were 0.941 (0.916–0.965) and 0.874 (0.802–0.946) for CSF and circulating NfL, corresponding to average sensitivities of 86% (79%–90%) and 91% (86%–95%), and specificity of 88% (82%–92%) and 76% (62%–85%), respectively.
These results strongly support the high diagnostic accuracy of both CSF and circulating NfL in differentiating PD from APS, highlighting their usefulness as promising biomarkers.