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 the onset may impact diagnosis and
treatment of BD.