Overview
- The University of Waterloo tracked 244 children with chronic physical illnesses for four years, collecting up to five hair samples to assess long-term cortisol exposure.
- Analysis identified three cortisol trajectories—hypersecretion (68%), hyposecretion (9%), and hyper-to-hypo (23%)—with persistently high levels associated with more anxiety, depression, and behavior problems.
- Children whose cortisol levels declined over time exhibited fewer emotional and behavioral symptoms than peers with consistently high cortisol.
- The findings were published in Stress and Health in September 2025, alongside related research in Brain and Behavior linking inflammatory blood biomarkers to future mental health trajectories.
- Authors describe hair cortisol as a promising, easy-to-collect risk marker, while noting single-site recruitment, a mostly White sample, and the lack of a healthy control group limit generalizability and require replication.