Hair Cortisol Concentration and Mental Disorder in Children With Chronic Physical Illness

BACKGROUND: To examine changes in hair cortisol concentrations (HCC) in children with chronic physical illness and identify patterns of association between HCC and mental comorbidity. METHODS: A sample of 50 children aged 6 to 16 years were recruited within six months of being diagnosed with a chronic physical illness. Data were collected via hair samples, structured interviews, and behavioral checklists. RESULTS: There was no change in HCC over six months. Baseline HCC was associated with internalizing—odds ratio (OR) = 1.29 (90% confidence interval (CI): 1.01–1.66)—and externalizing disorders—OR = 1.32 (90% CI: 1.07–1.64). Externalizing disorder at six months was associated with elevated baseline—OR = 1.25 (90% CI: 1.02–1.53)—and six-month HCC—OR = 1.25 (90% CI: 1.02–1.54). Associations between HCC and mental disorder weakened over time, and for internalizing disorders, changed direction (i.e., inverse association), albeit not significantly. CONCLUSION: Results provide preliminary evidence that physiological stress, measured using HCC, may be implicated in the relationship between physical and mental illness, and these associations align with attenuated stress responses over time.