To identify the prevalence of cognitive impairment (CI) as well as associated clinical factors and MRI-volumetric changes in myelin oligodendrocyte glycoprotein-IgG-associated disease (MOGAD).

All participants were investigated by certified neuropsychologists and underwent a standardised 3T-MRI at the University of Bochum. Images were processed with FreeSurfer for grey and white matter volume estimation. Sera were tested for a panel of autoantibodies (NMDAR-/CASPR2-/LGI1-/GABA-a/b/DPPX-/mGluR-IgG). The following clinical factors were included into analysis: disease duration, number and type of relapses, presence and type of supratentorial lesions, disability (EDSS), fatigue (FSMC), and depression (BDI-II).

32 MOGAD patients (19 females, 29.4 years (IQR 21.3-40.6)) were included. Median disease duration was 18 months with a median of two relapses and EDSS of 1.0. 20/32 patients had experienced optic neuritis, 17/32 myelitis and 8/32 ADEM-like episodes in their history. 7/32 patients (22%) suffered from CI with most prevalent deficits in mental flexibility (16.7%), alertness (11.1-14.4%) and verbal working memory (9.4%) in the cohort. 72.4% suffered from fatigue and 42.9% from depression. History of ADEM-like episodes was associated with CI (ExpB 7.333, 95% CI 1.168-46.052, p=0.034). Neither depression, fatigue, nor relapse rate or disability were risk factors. No coexisting antineuronal antibodies were found. Cerebral white and deep grey matter volumes were significantly reduced in MOGAD compared to healthy controls. Both history of ADEM-like lesions and CI were associated with reduced deep grey matter volume compared to unaffected MOGAD patients.

Every fifth MOGAD patient suffers from significant CI. Despite an almost complete resolution on conventional MRI, ADEM-like lesions in the history seem to be associated with CI and sustained deep grey matter atrophy.