HPA- and HPT-axis alterations in chronic posttraumatic stress disorder

Abstract

Posttraumatic stress disorder (PTSD) has been associated with dysregulation of the hypothalamus-pituitary-adrenal (HPA) axis as well as of the hypothalamus-pituitary-thyroid (HPT) axis. Findings have not been consistent and may depend on methodological issues like controlling for relevant variables. This study examines the levels of six HPA and HPT-axis related hormones in civilian PTSD patients without psychotropic medication. In a cross sectional study, 39 chronic PTSD patients and 44 healthy volunteers were included. Psychometric instruments included SCID, SI-PTSD, IES-R and BDI. The plasma hormones levels assessed were cortisol, dehydroepiandrosterone (DHEA), and dehydroepiandrosterone sulfate (DHEA-S), prolactin, thyrotropin (TSH), and free thyroxin (fT4). Results showed that patients had significantly lower plasma cortisol, prolactin and TSH levels compared to the comparison group. The difference between TSH levels in patients and comparison subjects only emerged after controlling for relevant background variables. Furthermore, the severity of PTSD symptoms was negatively related to cortisol levels. Secondary analyses revealed no statistically significant effect of comorbid depression (26% of patients) on any of the hormone levels. Complex feedback mechanisms are likely to result in altered levels of stress related hormones in PTSD, and results depend on controlling for relevant variables. Further research with longitudinal designs is needed to find out whether these lower hormone levels are preexisting risk factors or consequence of trauma and whether these alterations are deleterious or adaptive.