Influence of age on the cortisol response to dexamethasone

Controversy exists regarding the association of age with postdexamethasone serum cortisol levels. We evaluated this relationship in 95 patients with major depressive disorder and 49 healthy controls. Age and 8 a.m. postdexamethasone cortisol levels were not correlated among the healthy controls, but were positively associated among the depressives. There was also a trend for age and 4 p.m. postdexamethasone cortisol levels to be positively associated in depressives. Multiple linear regression analyses revealed that these associations could not be explained by other variables such as sex, psychotic features, or familial subtype of depression. Several hypotheses that might account for these associations are examined.