[The dexamethasone suppression test in depression. Critical review].

Within the investigation of the neuroendocrinology of depression, the HPA axis exploration brings the most definite results. Biological measurements indicate an hyperactivity of this system in the endogenous depressions. The dexamethasone cortisol suppression test has been described by Liddle and Nugent and has been used by Carroll since 1970. A standardisation of the protocol is required; thus, within the endogenous deficiencies, either lack of cortisol suppression or cortisol suppression with an early escape are noticed. The various and hazardous reasons that make the results vary are discussed. The dexamethasone suppression test is a practical and useful tool for the diagnosis of endogenous depression (sensitivity above 65%, specificity and diagnostical value near 95%); for treatment management; and prognostic evaluation. From a theoretical aspect, the dexamethasone test enables us to delineate the nosology of the depressive disorder and to detect in childhood depression the same neuro-endocrinological features as noticed in adulthood depression. Physiopathological hypotheses within the norepinephrinergic and serotoninergic depression theories are detailed.