Hair can help predict children’s stress, anxiety and depression

Children who reside with chronic illness have more than a bodily challenge. They are also apt to battle more psychological wars, like depression or anxiety. Scientists have struggled for decades trying to understand why.

Canadian universities are now delivering the answer, finding that biological markers related to stress and inflammation can identify which children are most prone to developing mental illness.

Researchers from the University of Waterloo tracked 244 kids with chronic physical illnesses for four years in one study. They used an unwitting measure of chronic stress: hair samples. Hair cortisol, a gauge of the level of stress build-up over time, was a robust predictor.

More than two-thirds of the children had chronically elevated cortisol. Those children were much more likely to be suffering from depressive, anxiety, or other emotional problems. Conversely, children whose cortisol levels fell had fewer psychological problems.

"Living with a chronic illness is to deal with everyday challenges such as having to take medication, school attendance and adjusting activity, all of which have a significant emotional effect," said Emma Littler, PhD student in Public Health Sciences at the University of Waterloo and lead author of the study. She continued that hair cortisol would help to determine children who would be most likely to benefit from early intervention.

Dr. Mark Ferro, Waterloo professor and co-author, observed that hair samples provide a non-intrusive way of tracking stress. "Hair cortisol is an unobtrusive, convenient biomarker that might be employed to screen children and track whether programs or interventions are reducing the pressure," Ferro said.

In another unrelated research, scientists looked to the immune system itself as a possible culprit. The Multimorbidity in Children and Youth across the Life-course (MY LIFE) study followed 263 children with illnesses such as asthma, diabetes, or juvenile rheumatoid arthritis. Of these, 128 provided blood samples that were screened for inflammatory biomarkers — proteins called cytokines that reflect how well the immune system is working.

For four years, researchers matched these blood markers against the kids' accounts of mood and behavioral symptoms. The result yielded dramatic patterns. High counts of granulocyte colony-stimulating factor (G-CSF) correlated with increased anxiety and depression. Another immune marker, granulocyte-macrophage colony-stimulating factor (GM-CSF), correlated with a broad array of issues, including aggression and hyperactivity.

Not everything inflammatory was bad news, however. Higher interleukin-6 (IL-6) levels, otherwise an indicator of pathological inflammation, were surprisingly linked to fewer behavioral and emotional difficulties. It suggests that not all immune information arrives in the brain with the same damage.

"These findings instruct us in a very valuable lesson that inflammation can play both beneficial and detrimental roles in determining mental health," Ferro stated.

Children themselves were reporting elevated symptoms early in the MY LIFE study. Their mean routine behavior and emotional scores were elevated enough to be concerning. Parents also saw challenges, but they reported fewer symptoms than children did. Parent reports of externalizing symptoms, like aggression, decreased some over time, but most other assessments were not shifting.

Interestingly, mental health scores were not significantly different by disease type. Whether or not a child had a neurological, respiratory, or endocrine illness was less important than whether he had chronic disease, in any case. That finding suggests that the interconnection between physical and mental health could be explained by underlying biological processes rather than the nature of any specific illness.

The two studies are also interesting in that they follow children through multiple years and not through occasional check-ins. What this permits researchers to observe is more about the trajectory of stress and inflammation and mental health problems. By controlling for child and parent report, the studies paint a clearer picture about how symptoms unfold.

There were some issues, however. Not enough occurrences of certain biomarkers during blood tests existed to be examined in any meaningful capacity. Medication histories, which could possibly taint results, did not exist, either. With that said, the evidence does show strong biological associations that are worthy of further examination.

Future studies will resolve whether and how these biomarkers will be helpful to doctors. If so, blood or hair samples obtained routinely can become a method of identifying children at greatest risk and referring them to earlier mental health treatment.

Behind the data points and statistics are children and families grappling with day-to-day challenges. Having a chronic illness usually involves lost school days, frequent treatments, and limitations on activities. Adding emotional issues to the load can be unbearable. These investigations underscore that body and mind must be attended to hand in hand, reminding parents and physicians that mind and emotional well-being at least should receive as much care as bodily ailment.

If it is possible to foretell future mental illness from inflammation and stress, doctors can even use quick tests — a vial of blood, a tuft of hair — to identify children at most risk. That could allow families to get help earlier, when issues don't spiral out of control.

For researchers, the findings underscore the significance of research into how the stress hormones and immune system affect the brain.

For society, it offers enhanced ways of taking care of chronically ill children, allowing them to lead healthier, more productive lives.

Research findings are available online in the journal Stress and Health.

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