Differential subtyping of depression

We studied a group of patients with depression divided into subtypes of non-chronic major depression, chronic major depression, and pure dysthymia. The purpose of this study was to determine if clinical and family history factors separated these types of depression. We reviewed records from semi-structured clinical interviews and abstracted data regarding factors that might differentiate these three depressive subtypes. In general we found what might be predicted from the definitions of dysthymia versus major depression, that is, ratings for severity of depression were lower for dysthymic patients as compared to patients with non-chronic or chronic major depression. We also found lower ratings for social functioning (GASF) for dysthymic patients as compared to the other depressive subtypes. Our study does not provide data to sufficiently separate these three subtypes. However, in the course of reviewing the literature on this topic, very few studies have separated patients into these distinct depressive subtypes. Further studies are needed to indicate if these subtypes can be meaningfully separated.