NEFL and amyotrophic lateral sclerosis: On the contrary, in the majority of investigated cohorts, including the recent large study by De Schaepdryver et al. (2020) on 383 ALS patients, CSF or serum NFL levels correlate moderately with the disease progression rate as expressed by the number of points lost on the ALSFRS-R score from disease onset divided by the disease duration from onset to sampling expressed in months (Gaiani et al., 2017; Illán-Gala et al., 2018; Verde et al., 2019b; Abu-Rumeileh et al., 2020; De Schaepdryver et al., 2020; Thouvenot et al., 2020; Table 2).