Contribution of Gray and White Matter Abnormalities to Cognitive Impairment in Multiple Sclerosis.

Xiaofei Zhang,Shengyuan Yu,Lin Ma,Dehui Huang,Lei Wu,Fangfang Zhang,Hua Liu,Jiong Shi,Yujun Zhao

doi:10.3390/ijms18010046

Abstract

Patients with multiple sclerosis (MS) commonly exhibit cognitive impairments (CI). However, the neural mechanisms underlying CI remain unclear. The current study applied diffusion tensor imaging (DTI) and voxel-based morphometric (VBM) magnetic resonance imaging (MRI) techniques to evaluate differences in white matter (WM) integrity and gray matter (GM) volume between MS patients with CI and MS patients with cognitive preservation (CP). Neuropsychological assessment and MRI were obtained from 39 relapsing-remitting MS (RRMS) patients and 29 healthy controls (HCs). Patients were classified as CI or CP according to cognitive ability, and demographic characteristics and MRI images were compared. Compared with HCs, MS patients exhibited widespread damage in WM integrity, and GM loss in several regions. Compared with CP patients, CI patients exhibited more extensive WM impairments, particularly in the corpus callosum, cerebellar peduncle, corona radiata, optic radiation, superior longitudinal fasciculus, anterior limb of the internal capsule, and cingulate, as well as decreased GM volume in the bilateral caudate, left insula and right temporal lobe. MS patients with CI exhibited more significant structural abnormalities than those with CP. Widespread impairments of WM integrity and selective GM atrophy both appear to be associated with impaired cognition in RRMS.

Highlights

Multiple sclerosis (MS) is a demyelination disease affecting the central nervous system (CNS), typically characterized by motor and sensory dysfunction, and optic neuritis
Researchers proposed that fractional anisotropy (FA) in the uncinate fasciculus was associated with processing speed and spatial memory [9], and Hulst et al found that white matter (WM) integrity was related to cognition in cognitive impairments (CI)–MS patients [10]
Tract-based spatial statistics (TBSS) detected significantly decreased fractional anisotropy (FA) and increased mean diffusivity (MD) and radial diffusivity (RD) in many WM tracts in MS patients compared with healthy controls (HCs)

Summary

Introduction

Multiple sclerosis (MS) is a demyelination disease affecting the central nervous system (CNS), typically characterized by motor and sensory dysfunction, and optic neuritis. Previous studies reported that 40%–70% of MS patients exhibit cognitive impairments (CI), primarily in learning, memory, information processing speed, and executive functions [1]. Hulst et al reported that only WM integrity was significantly different between CI and cognitive preservation (CP) patients, while no difference in regional GM volume was found [10]. Both RRMS and secondary progressive MS (SPMS) patients were enrolled in Hulst’s study [10]. Previous research indicated that cognition in SPMS patients was more frequently and severely impaired than among RRMS patients [15]. The current study aimed to further explore the neural basis of cognitive impairment by distinguishing CI and CP groups of RRMS patients according to cognitive ability, and examining them with a combination of DTI and VBM techniques

Comparison of Cognitive Test Scores

Comparisons of VBM between CI–MS Patients and CP–MS Patients

Participants

Neuropsychological Evaluation and Clinical Characteristic

MRI Image Acquisition and Analysis

Statistical Analysis