OBJECTIVE: The authors investigated the possibility of enhanced negative
feedback sensitivity of the hypothalamic-pituitary-adrenal (HPA) axis in
posttraumatic stress disorder (PTSD) by using a low dose of dexamethasone.
METHOD: Baseline blood samples were obtained at 8:00 a.m., and 0.5 mg of
dexamethasone was administered to 21 male patients with PTSD and 12 normal
age-comparable men at 11:00 p.m. Cortisol and dexamethasone levels were
measured 9 and 17 hours after dexamethasone administration. RESULTS: After
correction for differences in dexamethasone levels, the PTSD patients
showed greater suppression of cortisol in response to dexamethasone than
did the normal subjects. This was true even in patients meeting concurrent
diagnostic criteria for major depression. CONCLUSIONS: The data support
earlier studies showing that HPA abnormalities in PTSD are different from
those seen in depression and suggest that the low-dose dexamethasone
suppression test may be a potentially useful tool for differentiating the
two syndromes and further exploring differences in their
pathophysiology.Abstract Teaser