Originally included in the American Psychiatric Association's DSM-II,[citation needed], depressive personality disorder was removed from the DSM-III and DSM-III-R.
Some researchers argue that depressive personality disorder is sufficiently distinct from these other conditions so as to warrant a separate diagnosis.
Much of the controversy surrounding the potential inclusion of depressive personality disorder in the DSM-5 stems from its apparent similarities to dysthymia, a diagnosis already included in the DSM-IV.
Dysthymia is characterized by a variety of depressive symptoms such as hypersomnia, fatigue, low self-esteem, poor appetite, or difficulty making decisions, for over two years, with symptoms never numerous or severe enough to qualify as major depressive disorder.
Recent studies however, have found that dysthymia and depressive personality disorder are not as comorbid as previously thought.
An experiment conducted by American psychologists showed that depressive personality disorder shows a high comorbidity rate with major depression experienced at some point in a lifetime and with any mood disorders experienced at any point in a lifetime.