Sub-typing depression, III. Development of a clinical algorithm for melancholia and comparison with other diagnostic measures.

We describe the development of a clinical algorithm to differentiate melancholic from non-melancholic depression, using refined sets of 'endogeneity' symptoms together with clinician-rated CORE scores assessing psychomotor disturbance. Assignment by the empirically developed algorithm is contrasted with assignment by DSM-III-R and with several other melancholia sub-typing indices. Both the numbers of 'melancholics' assigned by the several systems and their capacity to distinguish 'melancholics' on clinical, demographic and a biological index test (the DST) varied across the systems with the algorithm being as 'successful' as several systems that include inter-episode and treatment response variables. Analyses provide information on the criteria set developed for DSM-IV definition of 'melancholia'.