Several reports indicate that Bipolar Disorder (BD) is frequently underdiagnosed

leading to overuse of antidepressants and underuse of mood stabilizers.

The aim is to review literature concerning this subject published since 2000.

BD seems to be frequently underdiagnosed. Several studies, as EPIDEP and NEMESIS, reveal insufficiencies on the diagnosis of this disorder, suggesting that clinicians miss this diagnosis about half of the times, and that about three quarters of these patients are not receiving appropriate treatment, respectively.

BD is often misdiagnosed as Major Depression Disorder (MDD), with approximately 40% of BD patients being initially diagnosed as MDD. On the other hand, a large fraction of patients initially diagnosed as MDD will change diagnosis to BD during follow-up, with some authors presenting values as high as 67%. Studies comparing the depressive features of MDD and BD point to some strong clinical indicators of bipolarity in patients presenting with depression, such as family history, seasonal pattern, postpartum onset, psychotic symptoms, younger age, suicidal behaviours, among others.

To a lesser extent, BD can also be misdiagnosed as: substance abuse, borderline personality, obsessive-compulsive disorder, among others.

It is also important to consider that a large fraction of patients with BD diagnosis will change diagnosis during the follow-up period.

BD patients with the diagnosis may represent only a fraction of the subjects with this disorder, and the true epidemiological extent of this problem needs further investigation.