Response to Dexamethasone and Subtype of Depression

This study examines the utility of the dexamethasone suppression test (DST) in identifying a clinically meaningful subtype of depression. Forty-nine inpatients who met research diagnostic criteria for major depressive disorder underwent DSTs and standard clinical assessments and ratings. Half of those with primary depression showed escape from dexamethasone suppression and are referred to as nonsuppressors, while few of those with secondary depression had this response. Most of the nonsuppressors were rated as having a good response to treatment, while only one third of the suppressors were rated as having a good response to treatment. These data suggest that pituitary adrenal disinhibition as assessed by the DST is selectively associated with primary depression. The DST may be a marker of a depressive subtype with a specific pathophysiology or pathogenesis.