Coping with stress before and after mild traumatic brain injury: a pilot hair cortisol study

Background: Cortisol is a crucial hormone for adaptation to challenging and stressful situations. Hair cortisol measurement is used to determine chronic stress; the growth rate of hair allows to determine averaged cortisol levels for a longer period. Objective: Pre- and post-injury measures of hair cortisol were compared in patients with mild traumatic brain injury (mTBI), and related to their coping styles. Methods: For 46 patients with mTBI, 3 cm scalp hair samples were collected 4-6 weeks post-injury, resulting in two 1 cm segments, pre- and post-injury. Hair samples were also collected for 11 healthy controls. Hair cortisol was quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Complaints, anxiety, depression and coping style were measured two weeks post-injury and long term (six-twelve months), added with measures for post-traumatic stress and functional outcome. Results: There were no differences between patients' pre- and post-injury cortisol levels, nor between cortisol levels of patients and controls. However, pre- and post-injury cortisol levels of patients were negatively correlated with both passive and an avoidant coping style. Conclusions: Our findings suggest that mTBI has no separate impact on chronic long-term cortisol levels, possibility indicating that variability in cortisol levels reflects individuals' premorbid characteristics determining coping with stress in general.