NEFL and amyotrophic lateral sclerosis: The levels of NfL and pNfH in blood positively correlated with disease progression rate (DPR) of ALS patients [NfL: summary r = 0.53, 95% CI (0.45–0.60), p < 0.01; pNfH: summary r = 0.51, 95% CI (0.24–0.71), p < 0.01].