Hair cortisol concentration and its association with acute stress responses and recovery in a sample of medical students in Germany

Introduction: Experiencing acute and chronic stress can contribute to adverse health outcomes. Responses to acute stress differ between individuals (i.e., stress reactivity) and the experience of chronic stress has been discussed to be associated with acute stress responses and stress recovery. This study thus aims to investigate whether hair cortisol concentration (HCC), being an indicator for hypothalamus–pituitary–adrenal (HPA) axis activity over a prolonged period of time, is associated with acute stress responses and recovery in a sample of medical students. Material and methods: From July 2020 to July 2021, medical students (n = 54) underwent a virtual-reality Trier Social Stress Test in which their blood pressure and heart rate variability (HRV) were measured, and hair samples were taken to determine HCC. Piecewise linear growth analyses were used to investigate whether HCC (categorized into low, medium and high levels) is associated with acute stress responses and recovery regarding blood pressure and HRV. Results: Significant interaction effects in piecewise linear growth analyses showed that participants with higher levels of HCC had lower systolic and diastolic blood pressure responses compared to participants with medium levels of HCC. No significant interaction effects were observed for HRV responses or for recovery measures. Conclusions: The study suggests that higher levels of HCC are associated with a lower cardiovascular response in terms of blood pressure to an acute stressor in medical students. Therefore, long-term HPA-axis activity may contribute to different magnitudes of acute stress responses in the autonomic nervous system. As the shown lower blood pressure responses to acute stress in individuals with increased long-term HPA-axis activity may represent inadequate stress responses, these should be further studied in order to find out more about their interaction and potential subsequent disease risks.