Differences in plasma ACTH and cortisol between depressed patients and normal controls.

Although studies have repeatedly demonstrated that depressed patients average higher baseline and postdexamethasone serum cortisol than normal controls, studies examining similar trends in adrenocorticotrophic hormone (ACTH) have produced conflicting results. The current study uniquely employs 48 hr of every 20-min serum sampling: the first 24 hr prior to dexamethasone administration and the second 24 hr subsequent. The depressed patients showed higher baseline cortisol levels than normal controls, with the greatest differences between 2 AM and 6 AM. After an 11 PM dose of dexamethasone, the difference was greatest between the hours of 8 AM and 4 PM. Among the depressed patients, those who reported recent weight loss had significantly higher plasma ACTH and cortisol levels than those without weight loss. Depressed patients without weight loss had higher baseline plasma ACTH than normal controls, and the differences reached significance during some time periods.