Adrenocortical hyperactivity in depression: effects of agitation, delusions, melancholia, and other illness variables

In an attempt to determine the relative contributions to adrenocortical hyperactivity in depression of agitation, delusions, and melancholic subtype, we measured cortisol levels before and after dexamethasone in 93 unipolar major depressed inpatients. Stepwise multiple regression showed that agitation predicted 22% of the variance in a.m. cortisol level after dexamethasone. Addition of the variables melancholia and delusionality to the regression model accounted for 27% and 34%, respectively, of the variance in the same cortisol variable. Age, illness severity, and weight loss added no further significant predictive value. Age, weight loss, and illness severity did affect cortisol levels when examined separately from the other variables. Rate of nonsuppression on the dexamethasone suppression test (DST) differed between the nonmelancholic major depressive group and any other group with melancholia. These results suggest why some discrepancies may exist between studies of the DST in delusional depression and indicate that agitation merits careful assessment in future studies of DST response.