Introduction: Current classification of bipolar disorder (BD) in type I or type II may be of little use in routine clinical practice to provide information on relevance epidemiological and clinical variables. New complementary coders like the predominant polarity (PP), which is defined as a clear tendency in the patient to present relapses in the manic polarity predominance (MPP) or in the depressive polarity predominance (DPP) along the disease may be important to develop clinical and pharmacological strategies to prevent any kind of relapse.
Objectives: To define the concept of PP and the epidemiological and clinical variables associated with the PP in order to know the clinical implications of that specific diagnosis factor.
Methods: We realized a systematic review in the principal medical databases (until June 2016) including key words as “bipolar disorder”, “polarity" and “predominant polarity”.
Results: After apply the inclusion criteria we analysed 16 articles. The MPP was associated with manic onset of illness, history of substance abuse before the beginning of the disease and with a better response to atypical antipsychotics and mood stabilizers. Meanwhile the DPP is related with a depressive onset of the disease, a higher number of relapses, longer acute episodes, and a higher risk of suicide. Also, the delay until the correct diagnosis, the presence of mixed states and the comorbidity with anxiety disorders are more frequents in DPP that shows an increased use of quetiapine and lamotrigine.
Conclusion: PP may be useful in the clinical management of BD. Further studies on biological and clinical factors are needed, with a common definition and a unified methodology