Exposure therapy with response prevention (ERP) is the most effective treatment for patients with obsessive-compulsive disorder (OCD), but associated with considerable temporary stress during initial sessions.

Amazingly, only scant information is available about stress hormone release during exposure therapy and its implication on therapy outcome in OCD.

To characterize hypothalamic-pituitary-adrenocortical activation during ERP treatment in OCD.

15 patients with OCD were studied twice from 13:00 to 16:00 - on the day before and of their first ERP therapy session (14:00 to 15:00). Subjective units of distress (SUD, 100 mm visual analogue scale) and salivary cortisol concentrations were assessed every 20 minutes.

Before and during (but not after) ERP SUD were significantly increased versus the control day (mean SUD before ERP: 49.8 vs. 31.4, mean peak vaules during ERP: 72.6 vs. 34.0). Salivary cortisol decresed significantly during the study period (as expected according to the regular diurnal rhythm), but no significant differences between ERP and the control day were detected at any time point.

Despite clear-cut psychological stress before and during ERP, no increased release of cortisol was observed. Our findings resemble respective results in panic disorder. Possible neurobiological underpinnings of this unexpected regulatory pattern will be discussed. Furthermore, we will speculate on the impact of lacking cortisol response on extinction learning during ERP.