Dexamethasone Suppression Test and Subtypes of Depression

To the Editor.— There is growing support for the use of the DST for diagnostic and treatment planning purposes in severe depressive illness.1-4The recent report by Schlesser et al in theArchiveslends support to that group's tripartite classification of primary unipolar depression, based on psychiatric history of first-degree relatives. In this and an earlier study'the Iowa group found that more than three quarters of patients with FPDD failed to show suppression of morning cortisol level after an overnight DST, with only a few percent of those with DSD similarly not showing suppression. We have tried to replicate their finding in a prospective fashion by performing the DST in consecutively admitted unipolar primary depressives who met Feighner5criteria for unipolar primary depression and Research Diagnostic Criteria (RDC)6for endogenous depression. In addition to 8AMblood samples as obtained in the Iowa protocol,3we drew samples