Cognitive function and brain magnetic resonance imaging profiles in neuromyelitis optica spectrum disorder and multiple sclerosis

Abstract

Background The objective of this study was to investigate cognitive performance and brain volume profile in patients with neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS). Materials and Methods: In a historical cohort study, 29 MS patients, 31 NMOSD patients, and 20 healthy controls (HCs) underwent neuropsychological assessment using the Minimal Assessment of Cognitive Function in Multiple Sclerosis (MACFIMS). Patients with MS and NMOSD also underwent a 1.5-tesla magnetic resonance imaging scan and high-resolution three-dimensional T1-weighted MPRAGE sequence. Results: The Symbol Digit Modalities Test scores were significantly lower in MS (mean standard deviation (SD) =44.1 14) and NMOSD (mean SD =45.5 14.3) patients compared to HCs (mean SD =57 9.5, P < 0.001). Scores of the Controlled Oral Word Association Test were also lower in MS (mean SD =25.9 9.8) and NMOSD (mean SD =24.6 10.2) patients compared to HCs (mean SD =36.6 9.8, P < 0.001). Additionally, the MS group performed worse on the Brief Visuospatial Memory Test (BVMT) compared to the NMOSD group (9.4 +/- 3.4 vs. 7.1 +/- 3.7 P < 0.001). In MS patients, there was a significant correlation between all cognition scores and total brain lesions, as well as between every test except BVMT-Revised with thalamic volumes. In NMOSD patients, a correlation was found between gray matter volume and the learning phase of the California Verbal Learning Test-II as well as between total lesion percentage and verbal memory and information processing speed. Conclusion: Both NMOSD and MS patients experienced impairment of information processing speed, working memory, and verbal fluency, whereas visuospatial memory impairment was only observed in MS patients. Despite lower total brain lesion and less thalamic atrophy, patients with NMOSD are at risk of cognitive impairment. Microscopic structural abnormalities may be a possible cause.