AQP4 and neuromyelitis optica: To examine cognitive function in pwMOGAD and assess relative risks (RR) for cognitive impairment (CImp) in pwMOGAD relative to healthy controls (HC), aquaporin 4-immunoglobulin G positive neuromyelitis optica spectrum disorders (pwAQP4+NMOSD), and double-seronegative NMOSD (pwdsNMOSD) compared to HC.