Gender differences in a cohort study of 604 bipolar patients: The role of predominant polarity

Background: Some clinical differences between gender regarding the course and outcome of bipolar disorders have already been described and some others remain still controversial. Aims: To explore gender differences regarding clinical and socio-demographic characteristics amongst bipolar patients with particular attention to predominant polarity and depressive symptoms. Method: Data were collected from DSM-IV type I and II bipolar patients (n = 604), resulting from the systematic follow-up of the Bipolar Disorders Program, Hospital Clinic of Barcelona, over an average follow-up of 10 years. Socio-demographic and clinical variables were collected in order to detect gender-related differences. Results: Bipolar women are more likely than men to show a predominance of depressive polarity as well as a depressive onset whilst men would be more likely to suffer from comorbid substance use disorders. Women significantly have a higher lifetime prevalence of psychotic depression and a higher prevalence of axis II comorbid disorders. Bipolar women are also more likely to have a family history of suicide and a lifetime history of attempted suicide. Suicide attempts are more often violent amongst bipolar men. In a backward logistic regression model, two variables were responsible for most gender-related clinical differences: type of predominant polarity - more likely to be depressive amongst women - (B = 0.794, p = 0.027, Exp(B) =0.452; CI= 0.223-0.915), alcohol abuse (B = 1.095, p = 0.000, Exp(B) = 2990; CI = 1.817-4.919) and cocaine abuse (B=0.784, p = 0.033, Exp(B)= 2.189; CI= 1.066-4.496) - more prevalent amongst men. Conclusion: The main characteristic featuring bipolar women is depression, both at illness onset and as a predominant polarity all along the illness course. This may have important diagnostic and therapeutic implications. (C) 2011 Elsevier B.V. All rights reserved.