To the Editor.—
In their family study of depressive subtypes, Leckman et al1 reported that 13.1% (8/61) of the patients meeting DSM-III melancholia criteria were not endogenous according to the Research Diagnostic Criteria (RDC). Faithful application of these criteria make such a finding highly unlikely, as shown by a comparison of the two sets of criteria (Table 1). Although the diagnostic symptoms are very similar, with each of the eight criteria used to diagnose melancholia that are also used to diagnose endogenous depression by the RDC, the algorithms used to arrive at each diagnosis are quite different. First, a diagnosis of melancholia requires both pervasive or near-pervasive anhedonia and a lack of reactivity, whereas the diagnosis of endogenous depression does not require any particular symptom to be present. Second, anhedonia appears in two places as part of the RDC criteria, once as pervasive anhedonia and then simply as anhedonia.
Zimmerman M, Coryell W. Validity of RDC and DSM-III. Arch Gen Psychiatry. 1985;42(6):633-634. doi:10.1001/archpsyc.1985.01790290115015