Testing DSM-IV definition of atypical depression.

The definition of atypical depression (AD) has recently seen a rebirth of studies, as the evidence supporting DSM-IV atypical features criteria is weak. Study aim was to test the validity of DSM-IV definition of AD. Consecutive 202 major depressive disorder (MDD) and 281 bipolar II outpatients were interviewed, during a major depressive episode (MDE), with the Structured Clinical Interview for DSM-IV. The relationships of DSM-IV AD versus variables often reported to distinguish AD and non-AD (gender, age, onset, bipolar II, axis I comorbidity, MDE severity, residual MDE symptoms, depressive mixed state), and versus bipolar family history, were tested. Each DSM-IV AD symptom's relationship with the variables found significantly associated to DSM-IV AD was then tested, in order to assess the degree of concordance among all AD symptoms. Associations were tested by univariate logistic regression (STATA 7). Frequency of DSM-IV AD was 42.8%. DSM-IV AD was significantly more common in bipolar II versus MDD (53.7% vs. 27.7%, p = 0.0000). DSM-IV AD significant associations were the following: bipolar II, female gender, lower age, lower age of onset, residual MDE symptoms, axis I comorbidity, psychotic features, depressive mixed state, and bipolar family history. Testing associations of each DSM-IV AD symptom versus the variables found associated to DSM-IV AD showed high concordance. All AD symptoms were significantly associated with DSM-IV AD, and with most study variables. Results support the current DSM-IV definition of AD.