title: Reduced CSF hypocretin-1 levels are associated with cluster headache.
abstract: BACKGROUND
  Cluster headache (CH) is a debilitating disorder characterized by unilateral, severe pain attacks with accompanying autonomic symptoms, often waking the patient from sleep. As it exhibits strong chronobiological traits and genetic studies have suggested a link with the hypocretin (HCRT) system, the objective of this study was to investigate HCRT-1 in CH patients.
  
  
  METHODS
  Cerebrospinal fluid HCRT-1 concentration was measured in 12 chronic and 14 episodic CH patients during an active bout, and in 27 healthy controls. The patients were well characterized and clinical features compared to the HCRT concentration.
  
  
  RESULTS
  We found significantly lower HCRT levels both in chronic (p = 0.0221) and episodic CH (p = 0.0005) patients compared with controls. No significant relationship was found with other clinical features.
  
  
  CONCLUSIONS
  This is the first report of significantly reduced HCRT concentrations in CH patients. We speculate that decreased HCRT may reflect insufficient antinociceptive activity of the hypothalamus. The mechanism of the antinociceptive effect of HCRT is not known and requires further investigation. This study supports the hypothesis of a connection between arousal regulation and CH.
authors.affiliation: Danish Headache Center, Dept. of Neurology, Glostrup Hospital, University of Copenhagen, Denmark.
authors.forename: Mads
authors.initials: M
authors.lastname: Barloese
authors.affiliation: Danish Center for Sleep Medicine, Dept. of Neurophysiology, Glostrup Hospital, University of Copenhagen, Denmark.
authors.forename: Poul
authors.initials: P
authors.lastname: Jennum
authors.affiliation: Danish Headache Center, Dept. of Neurology, Glostrup Hospital, University of Copenhagen, Denmark.
authors.forename: Nunu
authors.initials: N
authors.lastname: Lund
authors.affiliation: Danish Center for Sleep Medicine, Dept. of Neurophysiology, Glostrup Hospital, University of Copenhagen, Denmark Clinical Biochemistry Section, Dept. of Diagnostics, Glostrup Hospital, University of Copenhagen, Denmark.
authors.forename: Stine
authors.initials: S
authors.lastname: Knudsen
authors.affiliation: Norwegian Resource Center for ADHD, TS and Narcolepsy, University Hospital of Oslo, Norway.
authors.forename: Steen
authors.initials: S
authors.lastname: Gammeltoft
authors.affiliation: Danish Headache Center, Dept. of Neurology, Glostrup Hospital, University of Copenhagen, Denmark rigmor.jensen@regionh.dk.
authors.forename: Rigmor
authors.initials: R
authors.lastname: Jensen
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000134:cerebrospinal fluid; D003027:Cluster Headache / Q000134:cerebrospinal fluid* / Q000175:diagnosis* / Q000453:epidemiology; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000068797:Orexins / Q000134:cerebrospinal fluid*
chemical_list: D015415:Biomarkers; D000068797:Orexins
keywords: Cluster headache; hypocretin; hypothalamus; pain; sleep disorders