Fatigue and its association with sleep disorders, depressive symptoms and anxiety in patients with multiple sclerosis

Background and purpose: The aetiopathogenesis of fatigue in multiple sclerosis (MS) is not clear. It could be associated with structural changes of the central nervous system, but also with mood and sleep disorders. The purpose of the study was to evaluate frequency of fatigue and its association with sleep and mood disorders in MS patients. Material and methods: The examined group consisted of 122 MS patients (mean age 37.7 +/- 10.8 years). The following questionnaires were used: Fatigue Severity Scale (FSS), Epworth Sleepiness Scale (ESS), Athens Insomnia Scale (AIS), Montgomery-Asberg Depression Rating Scale (MADRS), and Hospital Anxiety and Depression Scale (HADS). Results: Fatigue was present in 75 MS patients (61.5%). Excessive daytime sleepiness was observed in 25 (20.5%), insomnia in 73 patients (59.8%). According to MADRS, depressive symptoms were present in 33 (27%), according to H ADS in IS people (12.3%). Anxiety was present in 32 patients (26.2%). We observed an association between fatigue (FSS) and sleep disorders (ESS, AIS) and also between fatigue and either depression (MADRS, HADS-D) or anxiety (HADS-A). The FSS score was not associated with age, sex, disease course and duration, Expanded Disability Status Stage (EDSS), treatment or level of education in MS patients. In inactive professionally people we noted significantly higher FSS scores (44.8 +/- 13.8) in comparison with active individuals (37.2 +/- 14.9; p = 0.0053). Conclusions: Fatigue is a very common symptom in MS, sometimes associated with sleep disorders, depressive symptoms or anxiety. The treatable causes of fatigue in MS such as sleep and mood disturbances should be identified and treated.