Predominant polarity in bipolar disorder: Diagnostic implications

BACKGROUND: It has been reported that patients with bipolar disorder (BD) remain about 10 years symptomatic before the correct diagnosis is made. This fact is particularly important for patients with predominantly depressed polarity who tend to be diagnosed as suffering from unipolar major depressive disorder and treated with antidepressants. The present study was carried out to assess clinical differences between predominantly manic and depressed BD patients with a special focus on the time that patients remained undiagnosed. METHODS: Clinical and socio-demographic characteristics were obtained from a sample of 149 euthymic bipolar outpatients. Patients were divided into depressive or manic predominance of polarity. Clinical features, number of years undiagnosed (NYU) and occupational functioning were assessed in the two groups. RESULTS: Forty-five patients were classified as a "Depressive Polarity" whilst forty-seven were considered as "Manic Polarity". Depressive Polarity was associated with a longer delay to be diagnosed (F=14.43, df=89, p=0.001). The predominantly depressive patients tended to present a depressive onset of illness, earlier age of onset, longer duration of illness and higher number of suicide attempts than manic polarity patients. CONCLUSION: There was a marked clinical difference between predominantly manic and depressive bipolar patients. Predominantly depressive polarity is associated with a longer delay in receiving a correct diagnosis and effective treatment which has an important impact on the management of the illness.