The utility of hair cortisol concentrations in the prediction of PTSD symptoms following traumatic physical injury.

RATIONALE: Although cortisol alterations have been associated with posttraumatic stress disorder (PTSD) and PTSD symptoms (PTSS), the direction of association is mixed. Cortisol which is measured in blood, saliva, or urine is subject to transient factors that may confound results. Recent advances in cortisol sampling techniques provide novel opportunities to address these inconsistencies. Hair cortisol sampling is a non-invasive method for the retrospective assessment of long-term integrated cortisol, yet its utility at predicting PTSS has not been assessed in acute injury victims.

OBJECTIVE: The aim of this prospective study was to examine whether higher levels of hair cortisol concentrations (HCC) were associated with increases in PTSS following traumatic physical injury.

METHOD: From January 2012 to May 2013, injury victims admitted to a level-1 Midwestern trauma center were recruited during their routine trauma clinic appointment within 30-days post-injury. Thirty participants had sufficient hair length to obtain 3-cm hair samples for cortisol assay. These participants completed PTSS assessments in relation to their recent injury at both the baseline and follow-up assessments (within 30- and 60-days post-injury, respectively).

RESULTS: Hierarchical regression analyses - which controlled for baseline PTSS, age, and sex - revealed that higher HCC predicted significant increases in overall PTSS at follow-up. Higher HCC also predicted increases in the avoidance/numbing subscale symptoms of PTSS. Dividing the avoidance symptoms and numbing symptoms into two separate clusters (consistent with the 4-factor DSM-5 model of PTSD) revealed that HCC was only marginally associated with numbing, but not with avoidance symptoms.

CONCLUSION: Hair sampling is a feasible method for assessing integrated cortisol levels soon after traumatic physical injury. This study suggests that elevated HCC may serve as a biomarker of risk for the development of posttraumatic symptomatology, and identifies specific symptoms that may be targeted for intervention in those with high HCC in the aftermath of injury.