The polarity of the index mood episode in bipolar disorder, and the predominant polarity over the course of the disease, can affect the treatment.1 Some medications appear to be more effective on more depressive symptoms, whilst others are more effective treating more manic symptoms.1
References:
1. Carvalho AF, Quevedo J, McIntyre RS, et al. Treatment implications of predominant polarity and the polarity index: a comprehensive review. Int J Neuropsychopharmacol 2014; 18 (2): pyu079.
2. Carvalho AF, McIntyre RS, Dimelis D, et al. Predominant polarity as a course specifier for bipolar disorder: a systematic review. J Affect Disord 2014; 163: 56–64.
3. Colom F, Vieta E, Daban C, et al. Clinical and therapeutic implications of predominant polarity in bipolar disorder. J Affect Disord 2006; 93 (1–3): 13–17.