Who’s the leader, mania or depression? Predominant polarity and alcohol/polysubstance use in bipolar disorders

Background: Predominant polarity characterises patients who mainly manifest recurrences of depression or mania/hypomania. Alcohol use disorder (AUD) and polysubstance use (PSU), which often complicate bipolar disorder (BD) and affect its clinical course, can influence predominant polarity. Nevertheless, previous studies have not clarified if BD patients differ in predominant polarity from BD patients with substance use disorder (SUD) comorbidity. Objective: The aim of this study was to compare predominant polarity between BD without SUD, BD with AUD and BD with PSU. We also investigated the association between predominant polarity and first episode polarity in each diagnostic group. Method: We evaluated predominant polarity (≥2:1 lifetime depressive vs. manic/hypomanic episodes) in 218 DSM-IV-TR BD patients. Specifically, data were obtained from 86 patients with BD without SUD, 69 patients with BD and AUD, and 63 patients with BD and PSU with alcohol as the primary substance abused. Results: The three groups significantly differed for predominant polarity. The most common predominant polarity in BD without SUD was manic, while in BD with AUD and in BD with PSU it was depressive. Uncertain predominant polarity was the least common in BD without SUD and BD with PSU, whereas in BD with AUD, manic predominant polarity was least common. Predominant polarity matched onset polarity in all groups. Conclusion: BD without SUD, BD with AUD, and BD with PSU have different predominant polarities. The correspondence between predominant polarity and polarity at onset may impact diagnosis and treatment of BD.