Paper
Persistent Depression: Should Such a DSM-5 Diagnostic Category Persist?
Published Nov 19, 2018 · G. Parker, G. Malhi
The Canadian Journal of Psychiatry
10
Citations
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Influential Citations
Abstract
DSM-5 has introduced yet another type of depressive diagnosis—persistent depressive disorder (dysthymia) (PDD)— which it describes as “a consolidation of DSM-IV-defined chronic major depressive disorder and dysthymic disorder” (p. 168). The condition and its definition have attracted little consideration and thus encouraged this critique. In light of its problematic status (as we review), we will argue for its potential inclusion, albeit modified as a duration specifier for major depression. Its criteria A and C require a depressed mood for at least 2 years (or 1 year in children and adolescents), for most of the day, for more days than not, and for the individual to not be without symptoms for more than 2 months over that period. Thus, while titled a “persistent” mood disorder with implications of constancy, its definition allows its absence across the day, over days, and for a period of up to 2 months. Thus, the first concern is that persistence is not mandated. Criterion B requires 2 or more of the following 6 symptoms: poor appetite or overeating, insomnia or hypersomnia, low energy or fatigue, low self-esteem, poor concentration or difficulty making decisions, and feelings of hopelessness. Other criteria allow a coterminous major depressive episode but disallow making the diagnosis in bipolar patients, in those with psychotic conditions, or when symptoms can be attributed to substance abuse or a medical condition. Criterion H requires that the symptoms cause “clinically significant distress or impairment in social, occupational or other important areas of functioning.” As noted earlier, PDD is positioned as a “consolidation” of DSM-IV chronic major depressive disorder (MDD) and dysthymic disorder. DSM-IV criteria for a chronic major depressive episode (MDE) include meeting MDE criteria “continuously for the past 2 years” (p. 382). However, as noted, persistence over 2 years is not mandatory for a diagnosis of PDD to be made. Criterion D for PDD states that “criteria for a major depressive disorder may be continuously present for 2 years,” in which case a diagnosis of both PDD and MDD should be assigned, while PDD specifiers allow MDD to be absent or, alternately, intermittently or persistently present over the preceding 2 years—and thus allow their independence rather than interdependence as suggested by the supposed coalescence of chronic major depression and dysthymia. In allowing that PDD can exist in the absence of MDD, it is unclear as to what is meant by “consolidation” of the 2 conditions. The term double depression emerged following the introduction of both MDD and dysthymia in the DSM-III manual. It is generally viewed as capturing a scenario whereby an individual experiencing dysthymia (i.e., a milder state of depression lasting for 2 years) has his or her condition worsen from time to time and leading in such instances to the development of MDD being “superimposed,” so that the term double depression presupposes 2 extant conditions. In clinical practice, what is most commonly observed is depressed individuals experiencing variation in depressive severity and with any MDD condition building on a less severe depressive base (including dysthymia) rather than there being 2 concurrent (and by inference distinguishable) conditions. The attempted “consolidation” of the 2 conditions increases heterogeneity along the severity axis while reducing heterogeneity along the chronicity dimensions, an issue of relevance when severity is more likely than chronicity to dictate treatment choice. The concept of “double
Persistent depressive disorder (dysthymia) in the DSM-5 should be considered as a duration specifier for major depression, but its inclusion should be modified to address concerns about persistence and interdependence between chronic major depression and dysthymia.
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