Predisposition or side effect of the duration: the reactivity of the HPA-axis under psychosocial stress in panic disorder.

Background: Panic disorder (PD) has been associated with an altered reactivity of the hypothalamic–pituitary–adrenocortical (HPA) system under psychosocial stress. Until now it remains unclear whether a diminished cortisol release is an early risk factor predisposing for PD or a consequence of PD. In order to unravel this point, the present study compares the cortisol secretion between patients with a recent onset and a chronic course of PD.
Methods: The Trier Social Stress Test (TSST) was applied in patients with a duration of PD ≤ 1.5 years (N = 35), patients with a duration of PD > 1.5 years (N = 56) and healthy controls (N = 95). Salivary cortisol and heart rate (HR) were assessed as primary outcomes.
Results: According to baseline cortisol/baseline HR and HR response there was no significant difference. Both patient groups (≤ 1.5/> 1.5 years) showed a blunted cortisol response with no significant group difference. In multiple linear regression models the attenuation of the HPA-axis was largely accounted for by group, smoking status, use of contraceptive pill and the interaction group by gender. Female patients with a chronic course showed the lowest cortisol response under the TSST.
Conclusions: It might be assumed that a decreased reactivity of the HPA-axis could be considered as etiological risk factor in the preliminary stages of PD. Above, female gender, smoking status and the use of contraceptive pill seem to further moderate the attenuated HPA-axis response pattern in patients with PD.