AQP4 and Cognitive impairment: On a functional level, cognitive impairment, which is a frequent symptom in AQP4-IgG+NMOSD, has previously been linked to gray matter, thalamic, and hippocampal volume loss.8,9 We are not aware of studies on the association of sGFAP with cognitive impairment in AQP4-IgG+NMOSD, which may be an interesting subject of future research.