Response to dexamethasone in affective disorder outpatients

Plasma cortisol suppression following 1 mg dexamethasone administration was investigated in patients with affective disorders. Twenty-nine depressed outpatients, 8 bipolar depressed inpatients during manic or hypomanic phase, and twelve healthy volunteers entered the study. Depressed patients were divided into 2 groups according to Research Diagnostic Criterio of Spitzer et al. (1978). The first group consisted of 10 patients affected by minor depressive disorders. The second group was formed of 19 patients with major depressive disorders (7 bipolar, 12 unipolar). No difference between patients and controls was found in baseline 4.00 p.m. serum cortisol levels. Healthy volunteers, patients with minor depressive disorders and bipolar subjects in manic or hypomanic phase showed normal suppression. On the other hand, only 42% of patients with major depressive disorders showed suppression. These results suggest that altered response to dexamethasone is a state-dependent phenomenon. Moreover, a dexamethasone suppression test is able to identify subgroups of suppressor in affected patients.