| Abstract: | As the clinical symptomatology of panic attacks may be conceivably related to abnormal brain stem activity, the present study examined the effect of lactate-precipitated panic on brain stem auditory evoked potentials (BSAEPs). The subjects were 27 patients who met DSM-III criteria for panic disorder (Pd), agoraphobia with panic attacks (AgPa) or agoraphobia (Ag). Following drug washout, patients were tested in two separate sessions, in a double-blind randomised controlled design in which each session involved two sequentially ordered BSAEP collection periods - a baseline period with no infusion followed by an intravenous infusion of 5% dextrose in water or 1.0 M sodium lactate (5 ml/kg in 5% dextrose/water) over a 20-min period. Of the 27 patients, 17 were clear responders, reporting panic attacks and self-report changes under lactate similar to those occurring during spontaneous panic. Of the remaining 10 patients, 6 were pseudo-responders, reporting panic symptoms under both dextrose and lactate, and 4 were non-responders. In the clear responders, lactate did not alter electrical events of the BSAEP, but further analysis within the clear responders, comparing AgPa patients with Pd patients, yielded a significant effect with lactate resulting in a prolonged III-V inter-peak interval in the AgPa group. It is suggested that the increased III-V interval in the AgPa group may be reflective of hyperactivity of brain stem noradrenergic nuclei. |
