Validity, reliability and prevalence of four 'clinical content' subtypes of depression

Although depression is often diagnosed via reference to a list of nine criteria which may be used to form a unitary diagnosis, there is significant variation in the content of those nine criteria to justify consideration of four 'clinical content' subtypes of depression based upon differences in symptomatology. Each of those four subtypes has previously been described for their different causes, underlying neurobiological pathways, and treatment requirements. This paper reports on the validity, reliability and prevalence of those four subtypes of depression across three samples of participants. Validity is demonstrated and satisfactory reliability values are reported for each subtype, plus significant correlations between items used to measure each subtype, arguing for the individual homogeneity of each of these four subtypes. Prevalence data indicated that there were significant subtype differences at the sample and individual level, challenging the usage of a single global depression score. These results argue for further consideration of these subtypes when researching depression and in planning individualised treatment regimes. (C) 2013 Elsevier B.V. All rights reserved.