Neuroendocrine Probes as Biological Markers of Affective Disorders: New Directions*

Numerous endocrine abnormalities are found in depressive illness and, among these, several have been proposed as useful markers in diagnosis, prediction of treatment response, monitoring treatment outcome or in understanding of etiology. This paper reviews five endocrine systems--the hypothalamic-pituitary-adrenal axis, hypothalamic-pituitary-thyroid axis, growth hormone regulation, prolactin regulation and pineal function, in which such abnormalities have been reported. The dexamethasone suppression test (DST) results are affected by a variety of other diseases and confounding conditions. Furthermore, variability in dexamethasone availability has recently been shown to be an important factor, influencing post-DST cortisol levels. Refined tests, taking into account all these factors, or alternative tests of hypothalamic-pituitary-adrenal function may lead to improved clinical utility. Pineal function is now the focus of considerable investigation. Low nocturnal output of melatonin is found in unipolar and bipolar affective disorder and is normalized by treatment with antidepressant drugs which block re-uptake of noradrenaline. These findings support the hypothesis of noradrenergic abnormality in depression. In seasonal affective disorder there is evidence for a phase delay in the melatonin rhythm which may be a key factor in the seasonal disorder. Effective light therapy causes a phase advance in the abnormal melatonin rhythm. Whether the normalization of the melatonin rhythm is instrumental in producing the antidepressant effect is yet to be determined. There are wide spread neuroendocrine abnormalities in depressive illness. These abnormalities encompass many different pituitary hormones, as well as the pineal.(ABSTRACT TRUNCATED AT 250 WORDS)