Other conditions that may present in a similar manner include attention deficit hyperactivity disorder, personality disorders, schizophrenia, and substance use disorder as well as a number of medical conditions.

A careful longitudinal analysis of symptoms and episodes, enriched if possible by discussions with friends and family members, is crucial to establishing a treatment plan where these comorbidities exist.

Since a diagnosis of bipolar disorder requires a manic or hypomanic episode, many affected individuals are initially misdiagnosed as having major depression and then incorrectly treated with prescribed antidepressants.