Dexamethasone suppression in depressed elderly outpatients.

The dexamethasone suppression test (DST) was performed as part of the preliminary workup in 85 previously untreated outpatients with major affective disorder, unipolar depressive type, who were over age 60. All patients were given a systematic structured interview (NIMH-DIS), and all had scores over 20 on the 21-item Hamilton Depression Rating Scale (HAM-D). Only 12 patients (14%) had positive DSTs; more of the non-melancholic (6 of 25; 24%) than melancholic (6 of 60; 10%) patients failed to suppress serum cortisol following standard dexamethasone challenge (p less than .10). DST results did not correlate with patients' HAM-D or Zung depression scores, gender, response to treatment, or any other variable studied. These findings suggest that, in comparison to previous reports, a positive DST may be 1) less common in major depressive disorders, 2) no more common in more severely depressed patients, and 3) less relevant to indications for specific treatment.