Utility and Limitations of Hair Cortisol in Clinical Research

Hair cortisol is a promising index for measuring chronic stress, having been applied in research on trauma, adverse experiences, resilience, and psychological interventions. However, its limitations include inconsistent results and interpretations across studies. The non-linear, two-stages timeline hypothesis may help address these limitations, as hair cortisol levels initially rise with stress and then decrease over time. Thus, rather than focusing on high or low levels, it is crucial to identify deviations from normal concentrations.