Hair Cortisol as a Biomarker of Traumatization in Healthy Individuals and Posttraumatic Stress Disorder Patients

Background: Previous evidence on endocrine correlates of posttraumatic stress disorder (PTSD) has been rather inconsistent. The analysis of cortisol in hair is a recent methodological development that may increase the quality of long-term cortisol assessments in such research. Here, we use this method to closely assess hair cortisol relationships with trauma-related characteristics and PTSD symptom patterns. Methods: Hair cortisol concentrations (HCC), diurnal salivary cortisol, and relevant psychometric data were assessed in matched groups of 28 PTSD patients and 27 traumatized and 32 nontraumatized healthy control subjects. Cortisol levels were quantified by liquid chromatography tandem mass spectrometry. Results: Posttraumatic stress disorder patients and traumatized control subjects exhibited 59% and 51% lower HCC than nontraumatized control subjects, respectively. Hair cortisol concentrations were found to be negatively related to the severity of intrusion symptoms, the number of different lifetime traumatic events, the frequency of traumatization, and the time interval since traumatization. The overall pattern of HCC associations was not reflected in short-term salivary cortisol findings. Conclusions: Our results indicate that trauma exposure per se, either in the absence or presence of PTSD, is a crucial correlate of long-term basal cortisol levels. Particularly, the experience of multiple events with a longer time since traumatization and an increased severity of intrusion symptoms may be related to hypocortisolism. The fact that HCC findings were not consistently seen in salivary cortisol data underscores the importance of the method of cortisol assessment and highlights the utility of hair cortisol analyses for future biological psychiatry research.