Objective: Current criteria for mixed bipolar episode do not allow an adequate understanding of a vast majority of bipolar patients with mixed (hypo) manic-depressive features, keeping the qualification of "mixed episodes" for bipolar type I only. This study was aimed to test the existence of a bipolar-mixed continuum by comparing the characteristics of three groups classified according to patterns of past and current manic or mixed episodes.
Method: 134 bipolar I inpatients were divided according to their pattern of excitatory "mixed-like" episodes in three groups: 1) lifetime history of purely manic episodes without mixed features (PMA); 2) lifetime history of both manic and mixed episodes (MIX) and 3) lifetime history exclusively of mixed, but not manic, episodes (PMIX). Differences in clinical and demographic characteristics were analyzed by using chi-square head-to-head for categorical data, one-way ANOVA for continuous variables and Tukey's post-hoc comparison. Logistic regression was used to control for data validity.
Results: PMIX had higher rates of depressive predominant polarity and less lifetime history of psychotic symptoms, and had received more antidepressants both lifetime and during 6 months prior to index episode. PMIX had more suicide attempts and Axis I comorbidity than PMA.
Discussion: PMIX is likely to have a higher risk for suicide and higher rates of comorbidities; current DSM-IV-TR criteria are not fit for correctly classifying these patients and this may affect treatment appropriateness. The concept of "mixicity" should be extended beyond bipolar I disorder to other bipolar disorder subtypes.
Copyright © 2011 Elsevier B.V. All rights reserved.