Cortisol secretion in endogenous depression. II. Time-related functions

Area of Science:

• Neuroendocrinology
• Psychiatry
• Chronobiology

Background:

• The hypothalamic-pituitary-adrenal (HPA) system regulates cortisol secretion.
• Dysregulation of cortisol is implicated in major depressive disorder.
• Previous studies suggest varied HPA axis abnormalities in depression.

Purpose of the Study:

• To investigate cortisol secretion patterns in endogenously depressed (ED) patients versus controls.
• To examine mean 24-hour cortisol levels, feedback mechanisms (dexamethasone suppression test), circadian rhythm, and ultradian rhythm.
• To determine if cortisol abnormalities in ED are a monolithic malfunction.

Main Methods:

• Collected 24-hour plasma cortisol samples from 32 ED patients and 72 controls.
• Analyzed mean cortisol levels, dexamethasone suppression test results, and circadian/ultradian rhythms.
• Controlled for age in analyzing secretory patterns.

Main Results:

• The primary difference observed was in the ultradian rhythm of cortisol secretion in ED patients.
• No significant advance in cortisol acrophase or nadir was found when age was controlled.
• An earlier timing of the first cortisol secretory episode during the night was noted in some ED patients.
• Abnormalities in specific cortisol functions were present in only some ED patients and showed limited overlap.

Conclusions:

• Abnormal cortisol secretion in depression is not a single, uniform malfunction.
• The ultradian rhythm appears to be a key differentiating factor in cortisol secretion patterns in endogenously depressed individuals.
• Cortisol secretion abnormalities in depression are heterogeneous and multifactorial.