Age effects in serial hypothalamic-pituitary-adrenal monitoring.

To evaluate age effects on hypothalamic-pituitary-adrenal (HPA) regulation in depressives, we studied 65 patients with major depressive disorder, endogenous subtype. With each patient serving as his or her own control, we compared weekly dexamethasone suppression test (DST) results among three age subgroups (less than 40 years, n = 18; 40-70 years, n = 40; greater than 70 years, n = 7). The oldest patient group had higher mean post-dexamethasone plasma cortisol concentrations both before and after treatment, and more were DST nonsuppressors. Life table analyses revealed that elderly patients who were DST nonsuppressors had significantly slower patterns of normalization during treatment and that fewer elderly patients ever achieved normal suppression. The results indicate that age effects on HPA function may be confounded with other aspects of depression, such as severity, chronicity and number of previous episodes.