title: Sex specific alterations in autonomic function among patients with irritable bowel syndrome.
abstract: BACKGROUND
  Irritable bowel syndrome (IBS) is associated with increased psychological symptoms, early life stressors, and alterations in visceral perception and brain responses to noxious visceral stimuli. The autonomic nervous system (ANS) is a likely mediator for these brain-gut interactions. The few studies directly examining ANS measures have been suggestive of alterations in some IBS patients, but no studies to date have examined the potentially critical variables of sex differences or response to visceral stimulation.
  
  
  OBJECTIVE
  (1) To test differences in ANS function during rest and during a visceral stressor (rectosigmoid balloon distension) between IBS patients and healthy control subjects. (2) To examine the role of sex on the autonomic responses of IBS patients.
  
  
  METHODS
  Baseline autonomic measures were evaluated from 130 Rome I positive IBS patients and 55 healthy control subjects. Data were also collected from a subset of 46 IBS patients and 16 healthy control subjects during a sigmoid balloon distension study. Heart rate variability measures of peak power ratio (PPR) and peak power high frequency (PPHF) were analysed to assess sympathetic balance and parasympathetic response, respectively. Peripheral sympathetic response was measured by skin conductance.
  
  
  RESULTS
  IBS patients showed a greater skin conductance response to visceral distension than controls. IBS patients had higher PPR and lower PPHF across conditions. Male IBS patients had higher skin conductance and PPR than females and lower PPHF.
  
  
  CONCLUSIONS
  IBS patients have altered autonomic responsiveness to a visceral stressor, with increased sympathetic and decreased parasympathetic activity. These differences are predominantly seen in males.
authors.affiliation: CNS/WH: Center for Neurovisceral Sciences and Women's Health, David Geffen School of Medicine at UCLA, Los Angeles, CA 90073, USA. ktillisch@mednet.ucla.edu
authors.forename: K
authors.initials: K
authors.lastname: Tillisch
authors.forename: E A
authors.initials: EA
authors.lastname: Mayer
authors.forename: J S
authors.initials: JS
authors.lastname: Labus
authors.forename: J
authors.initials: J
authors.lastname: Stains
authors.forename: L
authors.initials: L
authors.lastname: Chang
authors.forename: B D
authors.initials: BD
authors.lastname: Naliboff
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001341:Autonomic Nervous System / Q000503:physiopathology*; D002404:Catheterization / Q000379:methods; D003672:Defecation / Q000502:physiology; D005260:Female; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010275:Parasympathetic Nervous System / Q000503:physiopathology; D012007:Rectum / Q000503:physiopathology; D012737:Sex Factors; D013315:Stress, Psychological / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000503:physiopathology