Objectifying psychiatric diagnosis and treatment with the dexamethasone suppression test.

The application of the dexamethasone suppression test (DST) to the treatment of depressive illness is discussed from the perspectives of its use in diagnosis, the measurement of outcome, and the prediction of response to antidepressant medications. Patients with nonsuppressing depression occur in about one half of the endogenously depressed population and probably represent a norepinephrine-deficient subtype of the syndrome. There is clear evidence that a change in the DST from nonsuppression to suppression parallels recovery from a depressive illness, and this may be used as an objective measure of outcome. Early studies show promise that the DST can predict the antidepressant of choice, although there are some limitations of the DST in treatment choice.