Neuroendocrine investigation of depression in mentally retarded patients. A pilot study.

As part of a pilot study, eight adults with severe mental retardation were screened for the presence of endogenous depression by the standard 1-mg overnight dexamethasone suppression test (DST). The eight had been rigorously screened to rule out potential for false-positive DST. Two of the eight patients demonstrated nonsuppression, and a third had borderline results. Of these three, two manifested behavioral disturbances that could be attributed to major depressive disorder. The authors discuss the results, the difficulty diagnosing psychiatric disorders in severely retarded persons, and the proposed utility of the DST in this area.