Hypomanic and Major Depressive Episodes in Bipolar II Disorder must be distinguished from episodes of a Mood Disorder Due to a General Medical Condition. The diagnosis is Mood Disorder Due to a General Medical Condition for episodes that are judged to be the direct physiological consequence of a specific general medical condition (e.g., multiple sclerosis, stroke, hypothyroidism). This determination is based on the history, laboratory findings, or physical examination.
A Substance-Induced Mood Disorder is distinguished from Hypomanic or Major Depressive Episodes that occur in Bipolar II Disorder by the fact that a substance (e.g., a drug of abuse, a medication, or exposure to a toxin) is judged to be etiologically related to the mood disturbance. Symptoms like those seen in a Hypomanic Episode may be part of an intoxication with or withdrawal from a drug of abuse and should be diagnosed as a Substance-Induced Mood Disorder (e.g., a major depressive-like episode occurring only in the context of withdrawal from cocaine would be diagnosed as Cocaine-Induced Mood Disorder, With Depressive Features, With Onset During Withdrawal). Symptoms like those seen in a Hypomanic Episode may also be precipitated by antidepressant treatment such as medication, electroconvulsive therapy, or light therapy. Such episodes may be diagnosed as a Substance-Induced Mood Disorder (e.g., Amitriptyline-Induced Mood Disorder, With Manic Features; Electroconvulsive Therapy-Induced Mood Disorder, With Manic Features) and would not count toward a diagnosis of Bipolar II Disorder. However, when the substance use or medication is judged not to fully account for the episode (e.g., the episode continues for a considerable period autonomously after the substance is discontinued), the episode would count toward a diagnosis of Bipolar II Disorder.
Bipolar II Disorder is distinguished from Major Depressive Disorder by the lifetime history of at least one Hypomanic Episode. Attention during the interview to whether there is a history of euphoric or dysphoric hypomania is important in making a differential diagnosis. Bipolar II Disorder is distinguished from Bipolar I Disorder by the presence of one or more Manic or Mixed Episodes in the latter. When an individual previously diagnosed with Bipolar II Disorder develops a Manic or Mixed Episode, the diagnosis is changed to Bipolar I disorder.
In Cyclothymic Disorder, there are numerous periods of hypomanic symptoms and numerous periods of depressive symptoms that do not meet symptom or duration criteria for a Major Depressive Episode. Bipolar II Disorder is distinguished from Cyclothymic Disorder by the presence of one or more Major Depressive Episodes. If a Major Depressive Episode occurs after the first 2 years of Cyclothymic Disorder, the additional diagnosis of Bipolar II Disorder is given.
Bipolar II Disorder must be distinguished from Psychotic Disorders (e.g., Schizoaffective Disorder, Schizophrenia, and Delusional Disorder). Schizophrenia, Schizoaffective Disorder, and Delusional Disorder are all characterized by periods of psychotic symptoms that occur in the absence of prominent mood symptoms. Other helpful considerations include the accompanying symptoms, previous course, and family history.