The relationship between age and post-dexamethasone cortisol: a test of three hypotheses.

Previous studies report that DST nonsuppressors are older than normal suppressors. Data are presented on 188 primary unipolar major depressive inpatients and 35 healthy controls. In males, age appeared to correlate positively with post-dexamethasone cortisols in depressed patients and normal controls, although mean levels were higher in depressives. Female controls showed no consistent relationship between age and post-dexamethasone cortisol. A positive relationship did exist for depressed women. However, the association disappeared when age-of-onset was entered into the model, suggesting that in females early onset may identify a subtype of depression with normal DST suppression.