Association Between Hair Cortisol and Psychopathology in Children With a Chronic Physical Illness.

Children with a chronic physical illness (CPI) experience significant stress and are at a greater risk of psychopathology. However, little is known about chronic stress and its relationship with psychopathology in this population. Over the last decade, hair cortisol concentration (HCC) has emerged as a viable biomarker of chronic stress. This study identified trajectories of HCC in children with a CPI and examined their associations with psychopathology. The study included data from 244 children enroled in the Multimorbidity in Children and Youth across the Life-course (MY LIFE) study. MY LIFE is a prospective study of children aged 2-16 years with a CPI recruited from outpatient clinics at a Canadian paediatric hospital and followed for 48 months. Children provided 3-cm hair samples for cortisol assay and parents reported psychopathology symptoms using the Emotional Behavioural Scales. We 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%). When adjusting for sociodemographic and clinical characteristics, children in the Hyper-to-Hypo class had lower internalising (β = -3.17, p = 0.005) and externalising (β = -2.27, p = 0.007) psychopathology symptoms compared to the Hypersecretion class. This study provides evidence that children with a CPI follow distinct HCC trajectories. Children who followed a decreasing trajectory exhibited lower psychopathology symptoms compared to children who followed a consistently elevated trajectory, indicating that chronically high cortisol levels may contribute to the development of psychopathology.