Comparison of Cognitive Performance and MRI-Measured Brain Volume and Cortical Thickness between Patients with Neuromyelitis Optica Spectrum Disorder (NMOSD) and Multiple Sclerosis (MS): A Preliminary Report

Abstract

Objective: To investigate cognitive function and MRI-measured brain volume and cortical thickness in patients with neuromyelitis optica spectrum disorder (NMOSD) in comparison with those in patients with multiple sclerosis (MS). Methods: Forty-three patients with NMOSD, 34 with MS, and 31 normal controls (NCs) underwent neuropsychological tests and MRI examination. Cognitive impairment was considered if at least three cognitive domains were inferior to the 5th percentile for NCs. MRI measures included global brain volume, deep gray matter (GM) volume, and cortical thickness. Results: Cognitive impairment was seen in 28% of NMOSD and 53% of MS patients (P = 0.040). Visual memory (37%) and information processing speed (33%) were the most commonly impaired functions in NMOSD. In contrast, verbal memory (56%) was the most commonly impaired function in MS, followed by visual memory (41%) and information processing speed (41%). Performance scores of verbal memory were significantly different between NMOSD and MS, while no such differences were observed in other scores. MS patients exhibited more widespread and greater deep GM volume reduction and cortical thinning, while NMOSD patients showed regional GM volume reduction and cortical thinning. Brain volume and cortical thickness were not significantly different between NMOSD patients with and without cognitive impairment, whereas cortical thinning was associated with cognitive impairment in patients with MS (P = 0.027). Conclusion: Cognitive impairments were less common and less extensive in NMOSD patients than MS patients. Changes in brain volume and cortical thickness did not add to the predictive value for cognitive impairment in NMOSD.