Blunted stress cortisol reactivity and failure to acclimate to familiar stress in depressed and sub-syndromal children.

Depressed adults have shown blunted or elevated cortisol reactivity in response to various forms of psychosocial stress. However, there have been few studies of cortisol reactivity in children who had early onset depression or a history of depression during the preschool–school period. The present study utilized a laboratory stress paradigm and collected salivary cortisol from preschoolers at baseline (ages 3–5 years) and 24-month follow-up (ages 5–7 years). Repeated-measures multivariate analyses of variance (MANOVAs) were used to compare cortisol reactivity to mild stress between children with Major Depressive Disorder (MDD), elevated symptoms of depression (sub-syndromal MDD), and healthy controls. For healthy children, a quadratic cortisol reactivity curve was found at baseline (n=73), which appeared flatter under similar stressful situations at follow-up (n=14), which may reflect acclimation to the paradigm. In contrast, children with MDD (n=46) and sub-syndromal MDD (n=76) showed a peak cortisol response to the novelty of lab arrival and then reduced and blunted responses to stressors at baseline. These cortisol responses persisted at follow-up in children with a history of MDD (n=41) or sub-syndromal MDD (n=73). These results suggest that the hypothalamic–pituitary–adrenal (HPA) axis shows a blunted response to stress and failed to acclimate to familiar stressful situations in depressed and sub-syndromal depressed children.