Background: Previous studies found few abnormalities in hypothalamic-pituitary-adrenal (HPA) axis function in prepubertal children with anxiety or depressive disorders. In this study, we combined data from two independent, consecutive studies to achieve a larger sample size. Our goal was to identify potential alterations in the circadian pattern of cortisol secretion in anxious or depressed children.
Methods: A total of 124 prepubertal subjects from two independent samples (76 with major depressive disorder, 31 with anxiety disorders, and 17 healthy control subjects) were studied. Blood samples collected for cortisol at hourly intervals over a 24-hour period were examined. Analyses were performed aligning cortisol samples by clock-time. Additional analyses aligning samples by sleep-onset time were performed with a subsample of subjects.
Results: In the combined sample, significant findings emerged that were previously undetected. Anxious children exhibited significantly lower nighttime cortisol levels and an initially sluggish rise in cortisol during the nighttime when compared with depressed and healthy control children. In contrast, depressed children did not show a clear-cut pattern of differences compared with healthy control children.
Conclusions: Anxious children seem to exhibit an altered pattern of nighttime cortisol secretion, with an initially sluggish or delayed nocturnal rise before reaching similar peak levels of cortisol near the time of awakening. These findings suggest subtle alterations in HPA axis function in prepubertal children with anxiety disorders.