The dexamethasone suppression test and the diagnosis of depression in adults with severe and profound developmental disabilities.

The dexamethasone suppression test (DST) was administered to 40 adults with severe and profound mental retardation. All participants were free from known conditions which may have given misleading results from cortisol assay. Of nine participants who showed symptoms possibly indicating depression the DST results concurred in two cases (i.e. there were two true-positives). However there were four or five (depending on criteria adopted) false-positive DST results. There did not appear to be a consistent behavioural profile for positive DST responders. With sensitivity to possible depression estimated at 22%, and a diagnostic confidence of < 35%, these data do not support recommendations that the DST is useful for assisting in diagnosis of depression in this population.