Severity of depression and hypothalamic-pituitary-adrenal axis dysregulation: identification of contributing factors.

Severity of depression, as reflected by total scores on depression rating scales, has been established as one of several major sources of variance associated with hypothalamic-pituitary-adrenal axis dysregulation in patients with major depressive disorder. To determine which of the symptoms comprising clinically defined severity of illness contribute most to this relationship, we studied the associations between postdexamethasone plasma cortisol levels and components of the Hamilton Rating Scale for Depression (HRSD) in 114 patients with major depressive disorder. At pretreatment baseline, severity of depression was modestly but significantly correlated with postdexamethasone plasma cortisol; a large part of this relationship was associated with the anxiety components of the HRSD. When relationships between postdexamethasone plasma cortisol and severity measures were studied longitudinally during treatment, this contribution of the anxiety items persisted. The anxiety associated with depression appears to be a major clinical factor associated with the hypothalamic-pituitary-adrenal axis dysregulation in major depressive disorder.