DEPRESSION AND FATIGUE ARE DUE TO OBSTRUCTIVE SLEEP APNEA IN MULTIPLE SCLEROSIS.

To our knowledge, there is no study investigating whether fatigue and depression as the most commonly reported symptoms in multiple sclerosis (MS) and obstructive sleep apnea (OSA) patients have arisen from primary mechanisms of MS or from secondary associated conditions such as OSA in MS patients. The aim of our survey study was to determine whether depression and fatigue in MS patients were associated with clinical features of OSA or with MS. We conducted a self-administered survey using four validated questionnaires (STOP-BANG, Epworth Sleepiness Scale, Fatigue Severity Scale and The Center for Epidemiologic Studies Depression Scale-Revised) in 28 consecutive outpatients with proven MS. The prevalence of MS patients at an increased risk of OSA was 29% and age was positively correlated with this risk (p=0.019). None of the clinical features of MS patients (subtype, disability status, disease duration, modifying therapy, other medication) was correlated with depression and fatigue. On the contrary, excessive daytime sleepiness as a hallmark of OSA was significantly and positively associated with the level of depressive symptoms (p=0.004) and level of fatigue (p=0.015). Also, depression was significantly and positively correlated with the increased risk of OSA (p=0.015) and age of MS patients (p=0.016). Finally, a significant positive correlation was found between fatigue severity and level of depressive symptoms (p=0.003). OSA is a common disorder in MS patients. The clinical features and risk factors for OSA in MS patients are associated with the two most commonly reported symptoms of depression and fatigue, thus supporting the hypothesis that both symptoms are due to a secondary condition in MS.