Blunted salivary and plasma cortisol response in patients with panic disorder under psychosocial stress

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.

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.

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.

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.