Chronic Depression: Diagnosis and Classification

Traditionally, non-bipolar depression has been viewed as an episodic, remitting condition. However, with the recognition that depressions can persist for many years, the current diagnostic classification system includes various forms of chronic depression. The distinction between chronic and nonchronic depressions is useful for reducing the heterogeneity of the disorder. Individuals with chronic depression differ from those with nonchronic depression on a variety of clinically and etiologically significant variables, including comorbidity, impairment, suicidality, history of childhood maltreatment, familial psychopathology, and long-term course. In contrast, there is little support for current distinctions between different forms of chronic depression. This suggests that it may be simpler to collapse the existing forms of chronic depression in the current classification system into a single category. However, there is growing evidence that other characteristics, such as age of onset and a childhood history of early adversity, may provide meaningful approaches to subtyping chronic depression.