Self-assessment and characteristics of mixed depression in the French national EPIDEP study

Background: Studies on mixed depression have been conducted so far on the basis of DSM-IV manic symptoms, i.e., a list of 7 symptoms which may provide limited information on the subsyndromal features associated with a full depressive episode.

Methods: As part of the EPIDEP National Multisite French Study of 493 consecutive DSM-IV major depressive patients evaluated in at least two semi-structured interviews 1 month apart, 102 (23.8%) were classified as mixed depressives (≥3 hypomanic symptoms), and 146 (34%) as pure depressives (0 hypomanic symptom), after exclusion of bipolar I patients; hypomanic symptoms were assessed with the Multiple Visual Analog Scales of Bipolarity (MVAS-BP, 26 items) of Ahearn-Carroll in a self assessment format. A narrower definition of mixed depression, resting on those MVAS-BP items referring to DSM-IV hypomanic symptoms was also tested, as a sensitivity analysis.

Results: Compared to pure depressives, mixed depressive patients had more psychotic symptoms, atypical features and suicide attempts during their index episode; their illness course was characterized by early age at onset, frequent episodes, rapid cycling, and comorbidities. Mixed depressive patients were more frequently bipolar with a family history of bipolar disorder, alcohol abuse, and suicide. A dose-response relationship was found between intradepression hypomania and several clinical features, including temperament measures. The following independent variables were associated with mixed depression: hyperthymic temperament, cyclothymic temperament, irritable temperament, and alcohol abuse. Using the narrower definition of mixed depression missed risk factors such as suicidality and comorbidities.

Limitations: The following are the limitations of this study: retrospective design, recall bias, lack of sample homogeneity, no cross-validation of findings by hetero-evaluation of hypomanic symptoms.

Conclusions: EPIDEP data showed the feasibility and face validity of self-assessment of intradepressive hypomania. They replicated previous findings on the severity and high suicidal risk of mixed depression profile. They confirmed, for mixed depression, that mixed states occur when mood episodes are superimposed upon temperaments of opposite polarity. They finally suggested that a definition of mixed depression only based on DSM-IV-TR hypomanic symptoms may not allow to identify the most unstable subforms of the entity.