<unk>  refers to the co-existence of major depressive disorder (MDD) and persistent depressive disorder (PDD), (the latter was previously referred to as dysthymia). Research has shown that<unk>  tends to be more severe than either MDD or PDD alone and that individuals with<unk>  experience relapse more often than those with either MDD or PDD alone. However, there is some research that indicates few differences exist between<unk> , MDD, and PDD; as a result, those researchers conclude that<unk>  is not a distinct disorder. The literature that details the pharmaceutical treatment of<unk>  is sparse. Although there are studies that demonstrate that certain medications, such as selective serotonin reuptake inhibitors (SSRIs), are effective methods of treatment, those studies lack placebo controls; therefore, the studies' conclusions are questionable. Research has found that, as is the case with other depressive disorders, pharmaceutical and therapeutic treatments combined are more effective than the use of either form of treatment alone. Individuals with<unk>  tend to experience more functional impairment than those with either MDD or PDD alone. As a result, researchers emphasize the need for unique treatments for<unk>  to be developed and implemented.
Double depression
Long-term depression
Retarded depression
Outline of bipolar disorder
Treatment-resistant depression
Depression 
Late life depression
Recurrent brief depression