BACKGROUND: Panic disorder (PD) has been associated with an altered activity of the hypothalamic-pituitary-adrenal-cortical (HPA) axis. Recent findings from a patient sample with PD with secondary depression on psychotropic medication using salivary cortisol as outcome measure suggest a non-responsiveness of the HPA-axis under acute psychosocial stress. Salivary cortisol does not necessarily reflect the total plasma cortisol due to interfering variables. Whether the present findings can be replicated on a patient sample with pure PD using both salivary cortisol and total plasma cortisol as outcome variables remains to be elucidated.

METHODS: For this study, the Trier Social Stress Test (TSST) was implemented to assess the HPA-axis reactivity indicated by the plasma adreno-corticotropin-hormone (ACTH), plasma cortisol, and salivary cortisol release. The sample included 32 patients diagnosed with PD in a Structured Clinical Interview (SCID). Twelve male and fifteen female patients [mean age=32.87years, SD=11.23] were matched with 32 healthy controls by age and gender.

RESULTS: The plasma ACTH, total plasma cortisol and salivary cortisol release increased significantly in both groups due to the psychosocial stress test. The patients with PD showed a decreased plasma and salivary cortisol response as compared to the healthy controls. Plasma cortisol and salivary cortisol were highly correlated in both groups.

CONCLUSION: These findings provide strong evidence for a hypo-responsiveness of the HPA-axis as measured in both blood and saliva. Salivary and total plasma cortisol showed a strong concordance of results. Thus, future investigations could consider salivary cortisol as reliable marker of the HPA-axis under psychosocial stress.