Bipolar and unipolar disorders share a common depressive clinical manifestation, but have not the same treatment. An early recognition of bipolar depression has an important impact on the prognosis of bipolar disorder.

Our study aims at evaluating the prevalence of hypomania among patients with major depression and revealing the factors that distinguish between unipolar and bipolar depression.

Our cross-sectional study, in progress, includes outpatients with major depressive disorder, from the University Hospital in Sfax (Tunisia).

We use the Angst’s Hypomania Checklist (HCL-20) to detect episodes of hypomania misdiagnosed by the present psychiatrist.

Twenty patients were included. The average age of onset of disease was 31 years. More than half of patients were females (55%). Tobacco dependence was found in 35% of patients, alcohol dependence in 20% of them. Patients had a family history of bipolar disorder in 25% of cases. They attempted suicide in 15% of cases.

Hypomania prevalence was 45%. Hypomanic episode was more frequent in early-onset disease, when there is a history of attempted suicide, and in case of atypical or psychotic features. Addiction to tobacco or alcohol, presence of somatic comorbidity and mixed features were also more frequent in patients with past hypomania.

Our results show that bipolar disorder is underdiagnosed in depressive patients. Systematic search for hypomania, based on a clinical interview or a screening tool, is necessary to avoid misdiagnosis of bipolar disorder and therefore inappropriate treatment.