The contribution of disease severity, depression and negative affectivity to fatigue in multiple sclerosis: a comparison with ulcerative colitis.

Background: Fatigue is one of the most common and troubling symptoms of multiple sclerosis (MS) and more severe and disabling than fatigue in other somatic populations. Although fatigue seems MS specific, its pathogenesis is still poorly understood.

Objective: To study the disease specificity of fatigue in MS by comparing its level, its physical and psychological correlates to those of patients with ulcerative colitis (UC), a peripheral chronic auto-immune disease.