HYPOTHALAMIC-PITUITARY-ADRENAL AXIS ACTIVITY IN PANIC DISORDER - 24-HOUR SECRETION OF CORTICOTROPIN ANN CORTISOL

Background: Oversecretion of corticotropin-releasing hormone and/or dy sregulation of the hypothalamic-pituitary-adrenal (HPA) axis may contr ibute to pathophysiologic processes in panic disorder, but documentati on of HPA axis disturbance in panic has been inconsistent. In the curr ent study we examined HPA axis activity in panic disorder over a full circadian cycle, using frequent blood sampling to provide detailed ass essment of corticotropin and cortisol secretion.Methods: Twenty patien ts with panic disorder and 12 normal control subjects were studied. Bl ood samples were drawn every 15 minutes for 24 hours and assayed for c orticotropin and cortisol levels. Results: Patients with panic disorde r had elevated overnight cortisol secretion and greater amplitude of u ltradian secretory episodes. Patients who entered the study through cl inical referral channels had greater cortisol secretion than those rec ruited by advertisements. Patients with panic disorder who had a low f requency of panic attacks had elevated daytime corticotropin levels an d elevated corticotropin ultradian amplitude. Patients with a high fre quency of attacks had shifted corticotropin circadian cycles. Conclusi ons: Patients with panic disorder demonstrate subtle alterations in HP A axis activity, characterized by overnight hypercortisolemia and incr eased activity in ultradian secretory episodes, but HPA axis alteratio ns in panic are modulated by illness severity and treatment seeking. I t remains unclear whether HPA axis dysregulation in panic represents a pathogenic defect within the axis itself. Inconsistencies in prior wo rk may reflect the subtlety of the abnormalities seen, differences in clinical characteristics of patients studied, and the use of different probes and measurement contexts.