Background: Posttraumatic stress disorder (PTSD) has been associated with lower concentrations of cortisol and enhanced suppression of cortisol by dexamethasone, although discrepancies exist among reports. The objective of the study was to determine the pattern of cortisol responses in patients seeking treatment for PTSD resulting from a variety of traumatic experiences and to test whether cortisol responses are significantly related to childhood trauma, severity of symptoms, or length of time since trauma.
Methods: Salivary cortisol was measured at 8 AM, 4 PM, and 10 PM on 2 consecutive days before and after a 10 PM dose of .5 mg dexamethasone in 17 psychotropic medication and substance-free subjects with PTSD and 17 matched control subjects.
Results: Repeated-measures analysis of variance (ANOVA) of the baseline salivary cortisol concentrations demonstrated a significant effect for group with higher concentrations in the PTSD group but no significant differences in responses to dexamethasone. The presence of childhood abuse did not significantly affect salivary cortisol concentrations, and there was no correlation between predexamethasone cortisol and either the severity of PTSD symptoms or the time since the index trauma.
Conclusions: Neither low basal concentrations nor enhanced suppression of cortisol are consistent markers of a PTSD diagnosis.