Double depression refers to the co-existence of major depressive disorder (MDD) and persistent depressive disorder (PDD), the latter previously referred to as dysthymia. Research has shown that double depression tends to be more severe than either MDD or PDD alone and that individuals with double depression experience relapse more often than those with either MDD or PDD alone. However, there is some research that indicates few differences exist between double depression, MDD, and PDD; as a result, those researchers conclude that double depression is not a distinct disorder.
The literature that details the pharmaceutical treatment of double depression 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 psychotherapeutic treatments combined are more effective than the use of either form of treatment alone. Individuals with double depression 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 double depression to be developed and implemented.
Presentation
Individuals with double depression meet the DSM-5 classification criteria for both MDD and PDD. Goldney and Fisher (2004) determined that, in a sample of 3,010 individuals from southern portions of Australia calculated a prevalence rate of double depression of 2.2%. Jonas et al. (2003) reported a prevalence rate of double depression in the United States of 3.4%—based upon an assessment of 7,667 Americans. The prevalence rate of double depression can be compared to rates of PDD at 6.2%, major depressive episode (MDE) at 8.6%, and major depressive episode with severity (MDE-s) at 7.7%. Keller and Shapiro (1982) found that 26% of patients within a sample of 101 met the criteria for both MDD and PDD; however, the aforementioned sample is much smaller—and much more inclined to inaccuracies—than the samples (3,010 and 7,667) described above. Thus, double depression is less common than other forms of depression, but it is still a form of depression that warrants medical attention in the form of behavioral therapies, pharmaceutical treatments, or both (Miller, Norman, and Keitner, 1999). Levitt, Joffe, and MacDonald (1991) found that those with double depression experience fluctuations in mood at an earlier point in life, a more substantial number of depressive episodes, as well as co-morbid disorders of anxieties more often than their MDD-alone counterparts.
Hellerstein et al. (1994) theorized that antidepressant medications could be used to ameliorate both MDD and PDD; a pharmaceutical trial found that fluoxetine facilitated remission in 57.1% of patients after five months of treatment. In addition, Miller, Norman, and Keitner (1999) conducted an intervention in which one cohort received pharmaceutical treatment while another cohort received both pharmaceutical and psychotherapeutic treatment. Their results indicated that those who received the combined intervention were more functional—in a social sense—as well as relieved of their depression than those who received the pharmaceutical intervention alone (Miller, Norman, & Keitner, 1999).
Koran, Aboujaoude, and Gamel (2007) conducted a pharmaceutical trial with 24 adults who received duloxetine over the course of a 12-week period. Results showed that duloxetine was successful in the treatment of both PDD as well as double depression. However, the researchers' trial was an open-label trial; as a result, the researchers called for a double-blind and placebo-controlled trial to be conducted in order to further validate the benefits the medication seems to provide. However, the aforementioned trial (in addition to Koran et al.'s (2007) trial) 71% of cases that involved moclobemide—versus 38% of cases that involved fluoxetine—were determined to achieve the aforementioned desired outcome. As a result, the researchers concluded that both antidepressants were similar in their abilities to treat double depression in an effective fashion. However, the lack of a placebo control undermines the extent to which the results can be applied.
Marin, Kocsis, Frances, and Parides (1994) conducted an eight-week open trial that entailed the administration of desipramine to 42 individuals with double depression and 33 individuals with PDD. The researchers found that 70% of the PDD patients experienced a substantial improvement in clinical presentation; the proportion associated with the double depression-cohort was said to be similar. However, the lack of blindness as well as the lack of a placebo control were noted to be a considerable limitation of the aforementioned research. In addition, the researchers concluded that those with double depression acquire a more substantial number of treatment visits per month (a mean of 4.3) when compared to their MDD-alone counterparts (a mean of 3.0); their PDD-alone counterparts (a mean of 2.6); and their non-depressed counterparts (a mean of 1.5).
Prognosis
Although double depression is less prevalent than either MDD or PDD,
Controversies
Previous research on the clinical presentation of double depression tends to be mixed. Numerous studies indicate that the course of double depression tends to be more severe in nature.
See also
- Endogenous depression