BACKGROUND

Panic disorder (PD) has been associated with the altered circadian rhythm of the hypothalamic-pituitary-adrenocortical (HPA) axis. The findings regarding the stress-specific functioning of the HPA-system are inconsistent. It is also unclear whether the HPA-system response after the Corticotropin-Releasing-Hormone (CRH) challenge becomes altered.

METHODS

For this study, the dexamethasone-corticotropin-releasing-hormone (DEX-CRH) test was implemented to assess the HPA-axis reactivity indicated by the plasma adreno-corticotropin-hormone (ACTH) and the cortisol release. The sample included 32 patients diagnosed with PD in a Structured Clinical Interview (SCID). Fourteen male and eighteen female patients, [mean age = 33.50 years, SD = 12.76] were matched with 32 healthy controls by age and gender. Moreover, a sample of patients with unipolar depression (n = 21, ten females) was examined as a clinical control group.

RESULTS

In healthy controls as well as in patients with PD and patients with unipolar depression, the ACTH and the cortisol response increased significantly due to the CRH injection after dexamethasone pre-treatment. There were differences between the healthy controls and the patients with PD in the plasma cortisol response pattern, however, not in the ACTH. The patients with PD showed a decreased CRH-induced plasma cortisol response. A median-split gave evidence that patients suffering from PD longer than two years showed a remarkably higher HPA-axis reactivity under CRH-injection than patients suffering from PD two years or less.

CONCLUSION

These findings provide strong evidence that patients with PD show some dissociation between ACTH and cortisol response under the DEX-CRH test with strong indicators that the length of the duration of the psychopathology is a risk factor for an increased reactivity of the HPA-axis in patients with PD.