Comorbidity between dysthymic and major depressive disorders: A family study analysis

There is an extremely high rate of comorbidity between Dysthymic Disorder (DD) and Major Depressive Disorder (MDD). We used family study data to test four competing models of the relationship between DD, MDD, and comorbid DD/MDD: (1) DD, MDD, and DD/MDD are all variants of a single condition; (2) MDD and DD/MDD are similar, but differ from DD; (3) DD and DD/MDD are similar, but differ from MDD; and (4) all three conditions are distinct...