Should mood reactivity be included in the DSM-IV atypical features specifier?

The definition of atypical depression is still an unsolved issue. DSM-IV atypical features specifier criteria always require mood reactivity, but why mood reactivity should be included is unclear. The study aim was to test whether mood reactivity should be included in DSM-IV atypical features specifier.

Consecutively, 164 unipolar and 241 "soft" bipolar II major depressive episode (MDE) outpatients were interviewed with the Structured Clinical Interview for DSM-IV. The DSM-IV criteria for atypical features specifier were strictly followed. Associations were tested by univariate logistic regression.

MDE with atypical features was present in 41.4 % of patients. Bipolar II disorder was significantly more common in patients with atypical features. MDE with atypical features was significantly associated with bipolar II, female gender, lower age of onset, more axis I comorbidity, fewer psychotic features, and more depressive mixed states. In the whole sample, mood reactivity was significantly associated with all the atypical symptoms, apart from leaden paralysis, and all the other atypical symptoms were significantly associated with each other. In the bipolar II sub-sample, mood reactivity was associated with many, but not all, atypical symptoms, while in the unipolar sub-sample it was associated with no atypical symptom. Atypical symptoms were significantly more common in mood reactive than in non-mood reactive patients, apart from leaden paralysis. Bipolar II disorder and mood reactivity were strongly associated.

Results may support the inclusion of mood reactivity in the DSM-IV atypical features specifier for bipolar II disorder, but not for unipolar depression.