GFAP and amyotrophic lateral sclerosis: Blood-spinal cord-barrier (BSCB) disruption and leakage has been described in ALS patients and detachment of astrocytic end feet from vessels (Miyazaki et al., 2011) or regional differences in astrogliosis or GFAP expression (Schiffer et al., 1996; Oberheim et al., 2009; Sofroniew, 2015) are proposed to be responsible for a reduction of GFAP in the perivascular space (Waters et al., 2021).