The dexamethasone suppression test as an indication of depression in patients with mental retardation.

The Dexamethasone Suppression Test (DST) was performed for three groups of institutionalized patients with mental retardation: (a) patients with symptoms of depression, (b) nondepressed patients with other problematic behavior (aggressiveness, self-injurious behavior, or withdrawal), and (c) control subjects with no behavioral or psychiatric symptoms. Results showed that depressed patients more frequently (though not significantly) had positive DSTs and significantly higher cortisol levels compared with the other two groups. Patients with other problematic behavior did not differ from control subjects. The DST may be particularly valuable in diagnosing depression in individuals with severe mental retardation, who are often nonverbal and unable to express depressive symptoms.