A hair test may flag children with highest mental-health risk

Researchers report that cortisol levels found in hair samples may help identify children with chronic physical illnesses who face the greatest risk of developing anxiety and depression. The approach offers a long-term view of stress and may support earlier intervention.

The study, published this year in Stress and Health, followed 244 Canadian children living with chronic physical illnesses for four years. Investigators used hair cortisol as a biological marker that reflects accumulated stress. More than two-thirds of the children showed persistently high levels over the study period.

Researchers compared cortisol patterns with reports of emotional and behavioral difficulties. Children whose cortisol levels declined over time displayed fewer symptoms of anxiety, depression, and behavior problems than those whose levels stayed high. According to the research team, hair cortisol provides an easy and non-invasive measure that could one day be used to screen children and track whether treatments or support programs reduce stress.

An estimated 40 percent of children in Canada live with chronic physical illnesses, a proportion that has risen over recent decades. Prior findings show that those with higher cortisol levels develop mental health problems at rates between 20 percent and 50 percent, far higher than rates seen in healthy children. These conditions are linked to lower quality of life, suicidal thoughts, and increased use of health care services.

Hair sampling offers a months-long record of cortisol exposure because the hormone becomes embedded in the growing hair shaft. Human scalp hair grows about one centimeter per month, allowing each segment to reflect average stress levels for that period. Laboratory analysis includes cleaning, pulverizing, solvent extraction, and highly sensitive measurement of hormone levels.

A psychiatry specialist not involved in the study noted that anxiety and mood disorders are most commonly associated with chronic medical conditions and that cortisol changes signal increased risk for these disorders. She advised parents to watch for difficulties with learning, friendships, or enjoyment of usual activities, as well as disengagement in teenagers. Persistent sleep disruptions and challenges with age-appropriate tasks may also indicate stress.

The specialist said children with chronic diseases benefit from routines that remain as typical as possible while still accommodating their medical needs.