The HPA Axis and its Disturbances

Increased cortisol levels belong among the most significant biological markers of depressive disorders. This was known more than 30 years ago, when increased cortisol secretion (predominantly in the afternoon and early morning hours) was described [30]. 

Hypercortisolism in depression is the peripheral indicator of a general disturbance of the entire stress regulation. A primary reason for the enhanced cortisol release is obviously a central hypersecretion of CRH at the hypothalymic site [29, 31, 32]. The consequence of CRH hypersecretion is not only an increased cortisol level but also a down -regulation of glucocorticoid and mineralocorticoid receptors at the level of the pituitary and the hippocampus [33], i.e. a disturbance of the feedback system. 

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