Changes of concentration between Tlast and T1 for Nf‐L, Nf‐M, and Nf‐H Abs were higher in faster compared to slower progressing ALS individuals (Nf‐L Abs, p = 0.011; Nf‐M Abs p = 0.017 and Nf‐H Abs p = 0.01; Fig. 5B1) while Nf‐L ICs were higher in C9+ve compared to C9‐ve ALS patients (Fig. 5B2, p < 0.05). Here, NEFL is linked to amyotrophic lateral sclerosis.