Summary: Long-term stress measured through hair cortisol may help predict mental health risks in children living with chronic physical illnesses. In a four-year study of 244 children, researchers found that persistently high cortisol levels were strongly linked to symptoms of anxiety, depression, and behavioral problems.
Children whose hair cortisol declined over time showed fewer emotional and behavioral symptoms, suggesting that reduced stress is protective. The findings point to a simple, non-invasive biomarker that could support earlier identification and targeted intervention for vulnerable children.
Key Facts
- Stress signal: Hair cortisol reflects long-term exposure to stress and serves as a practical biomarker.
- High-risk group: Children with chronic physical illnesses (CPI) who maintain high hair cortisol are more likely to develop mental health problems.
- Early action: Routine screening of stress biomarkers could help clinicians and families detect children at higher risk and guide timely support.
Source: University of Waterloo
Long-term hair cortisol levels may offer important insight into mental health risk among children with chronic physical illnesses, according to new research from the University of Waterloo.
This research shows that hair cortisol — a steroid hormone that accumulates in hair and reflects stress over weeks to months — can act as an early warning sign to identify which children with CPI are most likely to develop emotional or behavioral difficulties. Using this biological measure alongside clinical assessments could help direct prevention and treatment to those who need it most.
An estimated 40 percent of children in Canada live with a chronic physical illness, a proportion that has been increasing. Compared with their peers, these children face higher risks for developing mental health conditions, which can lead to reduced quality of life, increased use of health services, and elevated risk of suicidal thoughts. Everyday burdens of chronic illness — including medication schedules, missed school, and activity limitations — can produce substantial and ongoing emotional strain.
Emma Littler, a PhD candidate in Public Health Sciences at Waterloo and the study’s lead author, explains that chronic stress related to living with a long-term health condition can take a heavy emotional toll. The study suggests that children with persistently elevated hair cortisol are more likely to experience anxiety, depression, and behavioral problems than those whose cortisol levels fall over time.
Over four years, the study followed 244 Canadian children with chronic physical illnesses, collecting 3-cm hair samples at intervals to measure cortisol and using parent reports to track emotional and behavioral symptoms. Researchers identified three distinct cortisol trajectories: a consistently elevated group, a consistently low group, and a group that transitioned from high to lower cortisol levels.
More than two-thirds of participants were classified in the consistently elevated cortisol group. Children in the group whose cortisol declined over time showed significantly fewer internalizing (e.g., anxiety, depression) and externalizing (e.g., behavioral) symptoms compared with children whose cortisol remained high. These associations held after adjusting for sociodemographic and clinical factors, indicating that persistent biological stress may contribute to the development of psychopathology.
Dr. Mark Ferro, professor in Waterloo’s School of Public Health Sciences and co-author of the study, notes that hair cortisol is a non-invasive and easy-to-collect biomarker that could eventually be used to screen children and monitor whether clinical or social supports are reducing chronic stress. Early identification of elevated stress could allow clinicians and families to intervene before emotional and behavioral difficulties become entrenched.
The study, titled Association between hair cortisol and psychopathology in children with a chronic physical illness, was published in the journal Stress and Health. It adds to a growing body of evidence that biological markers — whether found in hair or blood — can help predict trajectories of mental health for children facing long-term physical health challenges.
Researchers from Waterloo and McMaster University have also reported related findings showing that certain inflammatory biomarkers in blood may predict worsening or improvement in mental health among children with CPI. Together, these studies suggest that combining routine biological measures with regular mental health assessments could help healthcare providers identify children who would benefit from extra support earlier in the course of their illness.
About this mental health and neurodevelopment research news
Author: Ryon Jones
Source: University of Waterloo
Contact: Ryon Jones – University of Waterloo
Image: The image is credited to Neuroscience News
Original Research: Open access. “Association Between Hair Cortisol and Psychopathology in Children With a Chronic Physical Illness” by Emma Littler et al., Stress and Health.
Abstract
Association Between Hair Cortisol and Psychopathology in Children With a Chronic Physical Illness
Children with a chronic physical illness frequently experience significant, ongoing stress and are at elevated risk for psychopathology. Hair cortisol concentration (HCC) has become a useful biomarker for assessing chronic stress over time. This study examined HCC trajectories in children with CPI and how those patterns relate to emotional and behavioral symptoms.
The analysis used data from 244 children enrolled in the Multimorbidity in Children and Youth across the Life-course (MY LIFE) study, a prospective study of children aged 2–16 years recruited from outpatient clinics at a Canadian pediatric hospital and followed for 48 months. Hair samples provided measures of cortisol, and parents completed the Emotional Behavioural Scales to report psychopathology symptoms.
Researchers identified three HCC trajectories: (1) Hypersecretion (n = 166, 68.03%); (2) Hyposecretion (n = 21, 8.61%); and (3) Hyper-to-Hypo (n = 57, 23.36%). After adjusting for sociodemographic and clinical characteristics, children in the Hyper-to-Hypo group had significantly lower internalizing (β = −3.17, p = 0.005) and externalizing (β = −2.27, p = 0.007) symptoms compared with the Hypersecretion group.
Overall, the findings show that children with CPI follow distinct long-term stress trajectories and that decreasing cortisol over time is associated with fewer psychopathology symptoms. These results support the idea that chronically elevated cortisol may contribute to the development of mental health problems and that monitoring stress biomarkers could inform prevention and intervention strategies.