HPA axis responses to psychosocial stress in patients with social phobia

Despite social phobia (SP) being a common psychiatric disorder, to date, little is known about its underlying neurobiology. Findings regarding the HPA axis in SP have been inconsistent: Some studies found abnormal cortisol responses while other studies did not find any differences between SP patients and healthy controls. The present study was designed to test HPA axis functioning in response to psychosocial stress in patients with SP compared to healthy control subjects. 22 patients with DSM-IV SP and 17 age- and sex-matched healthy controls were examined. Both groups underwent the Trier Social Stress Test (TSST) while self-reported anxiety and endocrine measures (Cortisol, ACTH) were assessed.

Cortisol levels of the SP group were slightly, but not significantly higher at all time points compared to healthy controls. Regarding ACTH levels, there were no significant differences between patients with SP and healthy controls neither at baseline nor at any time point after TSST exposure. Compared to healthy controls, SP patients showed higher levels of subjective anxiety during the TSST. Patients with SP showed similar cortisol and ACTH responses to psychosocial stress, however, they perceived higher subjective anxiety during the TSST. These preliminary findings support the more cognitive models of SP (e.g. Clark & Wells, 1995), which regard biased processing of social information as a central mechanism for the maintenance of this disorder.