Is the DSM-5 duration criterion valid for the definition of hypomania?

Background: DSM-IV and DSM-5 impose a 4 day duration criterion for hypomanic episodes yet several studies have suggested that such an imposition may be invalid. We report a study involving a large sample pursuing the likely salience of the DSM duration criterion.

Methods: We analyzed data on hypomanic symptoms provided by two bipolar screening measures - the Mood Disorders Questionnaire (MDQ) and the Mood Swings Questionnaire (MSQ) in a sample of 501 patients meeting DSM and other symptom criteria for a bipolar II disorder (BP II) and contrasted data for 186 meeting the DSM minimum duration of 4 days and 315 experiencing episodes lasting less than 4 days (i.e. 'standard' vs. 'brief' groups).

Results: The brief group reported slightly less severe hypomanic episodes, but the two groups did not differ on a number of illness correlates including age of onset of depressive and of hypomanic episodes, or by rates of depressive and bipolar conditions in first-degree family members.

Limitations: The possibility of false positive BP II diagnoses, especially with brief hypomanic episodes, must be conceded while our examination of clinical symptoms was limited to two measures.

Conclusions: This study is consistent with previous studies suggesting that the DSM duration of 4 or more days for a diagnosis of a hypomanic episode is unnecessary to the clinical definition of a BP II disorder. Its preservation is likely to exclude a substantive number of those with a true BP II condition.