Racial differences in retinal neurodegeneration as a surrogate marker for cortical atrophy in multiple sclerosis

Background: Multiple sclerosis (MS) has both an inflammatory and a neurodegenerative component, with gray matter (GM) atrophy being an important contributor to disability. Optical coherence tomography (OCT) may serve as a prognostic tool for neuroaxonal health by measuring ganglion cell inner plexiform layer (GCIPL) thickness. There is a paucity of literature regarding the effects of race on pathobiology of MS, as racial minorities are underrepresented in research studies. Objective: The aim of this paper is to compare the correlation between GM fraction (GMF) and GCIPL thickness in Caucasian Americans with MS (CAMS) and African Americans with MS (AAMS). Methods: Fifty-nine patients with relapsing-remitting multiple sclerosis (RRMS) were included. Using a crosssectional design, we compared the OCT (GCIPL thickness) and MRI (GMF) data of 32 CAMS and 27 AAMS patients. Results: No significant correlation was observed between GMF and GCIPL in our study group (p = 0.127, r = 0.148). CAMS exhibited a significant correlation between these measures (p = 0.0004, r = 0.434), while in AAMS these measures did not correlate significantly (p = 0.187, r = - 0.201). Conclusion: GCIPL might be a sensitive biomarker predicting GM atrophy and disability in CAMS, but not in AAMS. Larger studies are needed to investigate reliable biomarkers across races. Inclusion of AAMS in research studies is necessary to shed more light on the pathobiology of MS.