Major Depressive, Manic, Mixed, and Hypomanic Episodes in Bipolar I 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 Major Depressive, Manic, or Mixed Episodes that occur in Bipolar I 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 Manic, Mixed, or 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., euphoric mood that occurs only in the context of intoxication with cocaine would be diagnosed as Cocaine-Induced Mood Disorder, With Manic Features, With Onset During Intoxication). Symptoms like those seen in a Manic or Mixed 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 I 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 I Disorder.
Bipolar I Disorder is distinguished from Major Depressive Disorder and Dysthymic Disorder by the lifetime history of at least one Manic or Mixed Episode. Bipolar I Disorder is distinguished from Bipolar II Disorder by the presence of one or more Manic or Mixed Episodes. 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 that do not meet criteria for a Manic Episode and periods of depressive symptoms that do not meet symptom or duration criteria for a Major Depressive Episode. Bipolar I Disorder is distinguished from Cyclothymic Disorder by the presence of one or more Manic or Mixed Episodes. If a Manic or Mixed Episode occurs after the first 2 years of Cyclothymic Disorder, then Cyclothymic Disorder and Bipolar I Disorder may both be diagnosed.
The differential diagnosis between Psychotic Disorders (e.g., Schizoaffective Disorder, Schizophrenia, and Delusional Disorder) and Bipolar I Disorder may be difficult (especially in adolescents) because these disorders may share a number of presenting symptoms (e.g., grandiose and persecutory delusions, irritability, agitation, and catatonic symptoms), particularly cross-sectionally and early in their course. In contrast to Bipolar I 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. Manic and depressive symptoms may be present during Schizophrenia, Delusional Disorder, and Psychotic Disorder Not Otherwise Specified, but rarely with sufficient number, duration, and pervasiveness to meet criteria for a Manic Episode or a Major Depressive Episode. However, when full criteria are met (or the symptoms are of particular clinical significance), a diagnosis of Bipolar Disorder Not Otherwise Specified may be made in addition to the diagnosis of Schizophrenia, Delusional Disorder, or Psychotic Disorder Not Otherwise Specified.
If there is a very rapid alternation (over days) between manic symptoms and depressive symptoms (e.g., several days of purely manic symptoms followed by several days of purely depressive symptoms) that do not meet minimal duration criteria for a Manic Episode or Major Depressive Episode, the diagnosis is Bipolar Disorder Not Otherwise Specified.