Atypical depression and its relation to bipolar spectrum

The relationship between atypical depression (AD) and bipolar (BP) spectrum is the relationship between BP-II and AD, because BP-II is the most common and best-studied disorder of the BP spectrum disorders. BP-II major depressive episode (MDE) versus unipolar (UP) MDE had a significantly higher frequency of AD, persisting when controlled for age. In BP-II MDE with a history of hypomania lasting less than 4 days, frequency of AD was significantly higher in comparison with UP MDE suggesting that a strong bipolarity may not be required to have more AD in BP-II. UP MDE switchers into hypomania during antidepressant treatment had features similar to the BP-II MDE switchers. Early-onset versus late-onset AD was significantly associated with female gender (+), number of MDE recurrences (+), BP-II (+), UP (-). Depressive mixed state was significantly more common in AD versus non-AD, and the association persisted when controlled for BP-II by logistic regression.