Fatigue in multiple sclerosis and its relationship to depression and neurologic disability

This is the authors' abstract. We don't add key points for this paper.

We studied multiple sclerosis fatigue (MSF) and its relationship to depression and disability. Seventy-one patients [50 relapsing-remitting, 21 secondary progressive] were grouped by Fatigue Severity Scale (FSS) into MS-fatigue (MSF) (FSS>/=5; n=46) or MS-nonfatigue (MSNF) (FSS</=4; n=20). Forty-one patients were grouped into MS-depression (MSD) (n=15) or MS-nondepression (MSND) (n=26) by interview. Higher expanded disability status scale (EDSS) scores were noted in MSF than MSNF patients (P=0.0003); EDSS scores correlated with FSS scores (rho=0.43, P=0.003). However, fatigue was present in 58% (n=29) of relapsing-remitting patients and in 52% (n=26) of patients with mild physical disability (EDSS<3.5). Hamilton/Beck depression severity scores were higher in MSF than MSNF patients and correlated with FSS scores (P<0.05). MSD had higher FSS scores than MSND patients (P=0.008). After controlling for EDSS, depression severity continued to correlate with FSS scores (rho=0.37, P=0.02). After controlling for depression, FSS scores no longer correlated with EDSS scores (rho=0.27, P=0.09). Thus, MSF is independent of physical disability, but is associated with depression, suggesting that common mechanisms play a role in MSF and MSD including psychological factors or brain lesions in specific neuroanatomic pathways. Further study is warranted to determine if antidepressant medications improve fatigue in MS.