The influence of psychiatric comorbidity on the dexamethasone/CRH test in major depression.

ABSTRACT

BACKGROUND: The outcome of the dexamethasone/corticotropin-releasing-hormone (DEX/CRH) test in depressed patients is heterogeneous. The present study investigated whether comorbidity of anxiety or somatoform disorders might be an explaining factor for this finding. METHODS: The DEX/CRH test was administered in 36 pure major depressive outpatients, 18 major depressive outpatients with a comorbid anxiety and/or somatoform disorder, and 43 healthy controls. Patients were free of psychotropic medication. Group differences in responsivity to the DEX/CRH test were analysed. RESULTS: Depressive patients with comorbidity showed a significant lower cortisol response compared to pure depressive patients (p = 0.04) and controls (p = 0.003). Group differences between MDD patients with and without comorbidity in cortisol responses disappeared after adjustment for post-DEX cortisol concentrations (p = 0.34). CONCLUSIONS: An enhanced suppression of cortisol to 1.5 mg DEX is present in a subgroup of depressed patients with psychiatric comorbidity. Distinct hypothalamic-pituitary-adrenal (HPA) axis dysfunctions are revealed when comorbidity is taken into account.