AQP4 and Brain atrophy: The main findings of this investigation are (1) sGFAP is associated with lower thalamus and hippocampus volumes in AQP4-IgG+NMOSD, (2) sGFAP is associated with a higher brain T2-lesion volume in AQP4-IgG+NMOSD, (3) sGFAP is associated with longitudinal brain atrophy in AQP4-IgG+NMOSD.