It’s all in the hair: Changes in hair cortisol concentrations in reaction to the COVID-19 pandemic predicts post-traumatic stress symptoms in children

Abstract

About 25 to 35% of victims of a traumatic event will develop post-traumatic stress disorder (PTSD). Low cortisol levels appear to be a risk factor for the development of PTSD. In adults, decreased diurnal and cumulative cortisol levels before or shortly after a traumatic event are associated with increased post-traumatic symptoms in the months thereafter. In contrast, results from the only two studies conducted in children showed that elevated diurnal cortisol levels shortly after exposure to a traumatic event are associated with more severe post-traumatic symptomatology. Given that a pandemic can induce post-traumatic stress symptoms, we investigated whether cumulative cortisol levels prior to and in the beginning stages of the COVID-19 pandemic in Quebec (Canada) predicted post-traumatic stress symptoms in children. We collected hair samples from 69 children (8-12 y/o) without history of psychopathology and exposure to a traumatic event. Cortisol levels were measured before (December 2019 - February 2020) and at the beginning of the pandemic (March 2020 - May 2020). Post-traumatic stress symptoms were assessed every 3 months between June 2020 (T1) and March 2021 (T4). The results showed that the percentage change in cumulative cortisol levels between the beginning of and prior to the pandemic predicted post-traumatic stress symptoms at T1. Specifically, a decrease in cortisol levels early in the pandemic was associated with increased post-traumatic stress symptoms. This study suggests that a decrease in cortisol in response to a stressful event may be a predisposing factor for PTSD in children.