Depressive psychomotor disturbance, cortisol, and dexamethasone

We examine the dexamethasone suppression test as a biological correlate of melancholia as defined by the CORE system, a scale for rating objective signs of psychomotor disturbance. Postdexamethasone cortisol concentrations and rates of nonsuppression were higher in CORE, Newcastle, and DSM-III-R defined melancholic groups. These differences, however, were no longer significant after partialling out the combined effects of age, dexamethasone, and basal cortisol concentrations. There was a significant correlation between the CORE (but not the Newcastle) scale and 8:00 AM postdexamethasone cortisol levels, which persisted after partialling out those same three covariates. Dexamethasone concentrations themselves were lower in CORE- and Newcastle-defined melancholics, though these were no longer significant after covarying for cortisol concentrations. Dexamethasone levels were also significantly inversely correlated with CORE and Newcastle scales. A significant correlation between CORE (but not Newcastle) scores and dexamethasone levels at 4:00 PM persisted after partialling out the effects of age and cortisol. These findings indicate an intriguing relationship between the CORE system as a dimensional construct for rating psychomotor disturbance, and both postdexamethasone cortisol and dexamethasone concentrations.