title: Proton magnetic resonance spectroscopy investigation of hyperventilation in subjects with panic disorder and comparison subjects.
abstract: OBJECTIVE
  The purpose of this study was to investigate differential effects of hyperventilation on brain lactate in patients with panic disorder and comparison subjects as a possible mechanism for explaining previous observations of an excess rise in brain lactate among panic disorder subjects during lactate infusion.
  
  
  METHODS
  Seven treatment-responsive patients with panic disorder and seven healthy comparison subjects were studied with proton magnetic resonance spectroscopy to measure brain lactate during controlled, voluntary hyperventilation over a period of 20 minutes. Hyperventilation was regulated with the use of capnometry to maintain end-tidal PCO2 at approximately 20 mm Hg during the period of hyperventilation. Blood lactate was measured prior to and at the end of hyperventilation.
  
  
  RESULTS
  At baseline the two groups had similar brain lactate levels. Panic disorder subjects exhibited significantly greater rises in brain lactate than comparison subjects in response to the same level of hyperventilation. Blood lactate levels before and after 20 minutes of hyperventilation were not significantly different between groups.
  
  
  CONCLUSIONS
  Controlled hyperventilation increases brain lactate and does so disproportionately in subjects with panic disorder. This increase in brain lactate may result from decreased cerebral blood flow due to hypocapnia, and individuals with panic disorder may have greater sensitivity to this regulatory mechanism.
authors.affiliation: Department of Psychiatry, University of Washington School of Medicine, Seattle, USA.
authors.forename: S R
authors.initials: SR
authors.lastname: Dager
authors.forename: W L
authors.initials: WL
authors.lastname: Strauss
authors.forename: K I
authors.initials: KI
authors.lastname: Marro
authors.forename: T L
authors.initials: TL
authors.lastname: Richards
authors.forename: G D
authors.initials: GD
authors.lastname: Metzger
authors.forename: A A
authors.initials: AA
authors.lastname: Artru
mesh_terms: D000328:Adult; D001921:Brain / Q000378:metabolism*; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D006985:Hyperventilation / Q000378:metabolism*; D016857:Hypocapnia / Q000378:metabolism; D007773:Lactates / Q000032:analysis / Q000097:blood / Q000378:metabolism*; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D016584:Panic Disorder / Q000378:metabolism*
chemical_list: D007773:Lactates