Normal Appearing White Matter N-Acetylaspartate Changes Impact on Fatigue in Multiple Sclerosis

Abstract

Background: Fatigue is one of the most frequent complaints presented by multiple sclerosis patients. Fatigue may be multifactorial. Proton magnetic resonance spectroscopy studies have shown significant reductions in N-acetylaspartate/creatine ratios in multiple brain regions among fatigued multiple sclerosis patients in comparison to non-fatigued multiple sclerosis patients, suggesting axonal loss as a contributing factor. Females are twice as likely to develop the disease. Aim: To evaluate gender variability in fatigue scores in relapsing-remitting multiple sclerosis patients. To explore potential gender differences in metabolite profiles of normal appearing white matter. To correlate metabolite changes distribution with fatigue severity and to evaluate the gender impact. Methods: We enrolled 50 relapsing-remitting multiple sclerosis patients on disease modifying treatment and 28 healthy controls. All participants underwent proton magnetic resonance spectroscopy of normal appearing white matter corresponding regions and fatigue severity evaluation. Results: We found higher fatigue scores in the multiple sclerosis group, due to greater severity in female subjects. We found a significant decrease of N-acetylaspartate/creatine ratio with increase in N-acetylaspartate, choline, and creatine levels in multiple sclerosis subjects. N-acetylaspartate and choline levels were significantly higher in the multiple sclerosis males. Female multiple sclerosis patients presented with lower N-acetylaspartate levels than healthy controls and greater increases in Fatigue Severity Scale score. Regression analysis revealed metabolite specific relationships between fatigue against metabolite variables. Conclusion: Proton magnetic resonance spectroscopy registered differences in metabolite profiles in normal appearing white matter male and female multiple sclerosis subjects. We might presume gender dependent specifiers in metabolite profiles in relapsing- remitting multiple sclerosis. They impact fatigue severity. N- acetyaspartate might be crucial contributor in central fatigue in multiple sclerosis. Bioenergetic role of N-acetylaspartate needs further collaborative research on genetics and electrical properties of neurons to reveal the underlying mechanism of fatigue and conductivity deterioration.