CSF hypocretin-1 concentrations correlate with the level of fatigue in multiple sclerosis patients

Considering the multiplicity of symptoms associated with multiple sclerosis (MS), there is possibility that hypocretin system function might be involved in the pathogenesis of the disease. The current study aimed to investigate the hypocretin-1 levels in cerebrospinal fluid (CSF) of MS patients in relation to different neurological deficit measures including: Ambulation Index (AI), Expanded Disability Status Scale (EDSS), Fatigue Severity Scale (FSS), and Epworth Sleepiness Scale (ESS) in relapse-onset MS patients. 53 subjects were included into the study: 38 patients with a diagnosis of MS and 15 healthy controls. Among MS patients, 25 had relapsing-remitting and 13 secondary progressive MS. CSF hypocretin-1 levels did not differ between MS patients and healthy controls (p>0.05). A positive correlation between hypocretin-1 level and fatigue level was found in MS patients (p<0.05) and this effect was even stronger in the MS subgroup suffering from fatigue (p=0.01). Hypocretin system seems to be generally unchanged in MS but a positive correlation between hypocretin-1 level and fatigue may indicate involvement of some compensatory mechanisms stimulating the production of the neuropeptide in MS patients.