Alterations in hypothalamic-pituitary-adrenal axis feedback regulation have been repeatedly reported in patients with borderline personality disorder (BPD). Due to the cross-sectional design of these studies, little is known about the longitudinal course of HPA axis functioning. In a sample of 13 patients with BPD, the dexamethasone suppression test (DST) has been used in a one-year follow-up study. There were no changes of cortisol concentrations before or after dexamethasone intake between baseline and follow-up examination. Patients with comorbid posttraumatic stress disorder (PTSD) showed more pronounced cortisol suppression compared to those without PTSD. The DST seems to be a stable marker of alterations in HPA axis feedback regulation in BPD, which is also reflected by substantial correlations between percentage of cortisol suppression at baseline and follow-up examination.
