Neurofilament light chain
protein (NfL) is currently the most accurate cerebrospinal fluid (CSF)
biomarker in
amyotrophic lateral sclerosis (ALS) in terms of both diagnostic and prognostic value, but the mechanism underlying its increase is still a matter of debate. Similarly, emerging CSF
biomarkers of neurodegeneration and
neuroinflammation showed promising results, although further studies are needed to clarify their clinical and pathophysiological roles. In the present study we compared the diagnostic accuracy of CSF NfL, phosphorylated (p)-tau/total (t)-tau ratio,
chitinase-3-like protein 1 (YKL-40) and
chitotriosidase 1 (CHIT1), in healthy controls (n = 43) and subjects with ALS (n = 80) or ALS mimics (n = 46). In ALS cases, we also investigated the association between
biomarker levels and clinical variables, the extent of upper motor neuron (UMN) and lower motor neuron (LMN) degeneration, and
denervation activity through electromyography (EMG). ALS patients showed higher levels of CSF NfL, YKL-40, CHIT1, and lower values of p-tau/t-tau ratio compared to both controls and ALS mimics. Among all
biomarkers, NfL yielded the highest diagnostic performance (> 90% sensitivity and specificity) and was the best predictor of
disease progression rate and survival in ALS. NfL levels showed a significant correlation with the extent of LMN involvement, whereas YKL-40 levels increased together with the number of areas showing both UMN and LMN damage. EMG
denervation activity did not correlate with any CSF
biomarker change. These findings confirm the highest value of NfL among currently available CSF
biomarkers for the diagnostic and prognostic assessment of ALS and contribute to the understanding of the pathophysiological and electrophysiological correlates of
biomarker changes.