We evaluated the role of plasma cortisol levels in determining sodium lactate–induced panic by reporting psychological, physiological, and biochemical data collected from an extended sample of 214 subjects during the "placebo" infusion (isotonic saline solution) immediately preceding the lactate infusion procedure.
One hundred seventy patients with panic disorder, 101 (59%) of whom were assessed to have panicked (P group), and 69 (41%) who were assessed not to have panicked (NP group) with lactate infusion; and 44 normal healthy volunteer controls (1 of whom panicked with lactate infusion) were studied.
Before the lactate infusion, the P group exhibited hypothalamic-pituitary-adrenal (HPA) axis activation (high plasma cortisol levels) and evidence of hyperventilation (low PCO2 levels) in comparison with NP and control groups. Self-reported fear, dyspnea, and diastolic blood pressure were highest in the P group, intermediate in the NP group, and lowest in the control group. Within the P group, baseline fear scores correlated inversely with PCO2 levels and positively with cortisol levels while PCO2 levels correlated negatively with cortisol levels. Significant predictors of lactate-induced panic were prelactate infusion fear and the interaction of high cortisol levels and low PCO2 levels.
Combined data suggest that synchronized elevations of HPA axis activity, self-reported fear, and hyperventilation during the period before lactate infusion predisposes to lactate-induced panic.