Am J Psychiatry. 1995 May;152(5):666-72.
Proton magnetic resonance spectroscopy investigation of hyperventilation in subjects with panic disorder and comparison subjects.
Dager SR, Strauss WL, Marro KI, Richards TL, Metzger GD, Artru AA.
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.
METHOD:
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.
Am J Psychiatry. 1995 May;152(5):692-7.
Effect of chloride or glucose on the incidence of lactate-induced panic attacks.
George DT, Lindquist T, Nutt DJ, Ragan PW, Alim T, McFarlane V, Leviss J, Eckardt MJ, Linnoila M.
OBJECTIVE:
This study was designed to test the hypothesis that the addition of chloride to a lactate infusion would reduce the frequency of panic attacks.
METHOD:
The subjects included 14 healthy volunteers and 20 patients meeting the DSM-IV criteria for panic disorder. All subjects received an infusion of lactate dissolved in 0.9% sodium chloride and an infusion of lactate dissolved in 5% dextrose in water on separate days in a random-order, double-blind procedure. Blood pressure, heart rate, and panic symptoms were measured at 3-minute intervals during the infusions. The occurrence of panic attacks was ascertained through the subjects’ reports of losing control, panicking, or “going crazy” and the presence of at least four Research Diagnostic Criteria symptoms of a panic attack.
RESULTS:
Fifteen (75%) of the patients with panic disorder reported a panic attack during one of the infusions or both; no healthy volunteers had a panic attack. The patients with panic disorder were significantly more likely to have a panic attack during the lactate/sodium chloride infusion than during the infusion of lactate/5% dextrose in water. The number of panic attack symptoms reported at 3-minute intervals did not differ between the two types of infusion.
CONCLUSIONS:
The coadministration of glucose resulted in a reduced sensitivity to the panicogenic effects of lactate. The hypothesis that adding chloride to the infusion would reduce the frequency of lactate-induced panic attacks was not supported.
