Bipolar disorders involve distinct periods, called episodes, during which disturbances in mood and behavior are present. Episodes may be depressive, manic, hypomanic or mixed. Major depressive episodes are characterized by depressed mood and lack of interest for at least two weeks. Manic episodes are defined as a week or more of elevated or irritable mood, whereas hypomanic episodes last four to seven days. Periods of time during which criteria for both manic and major depressive episodes are met are known as mixed episodes.
Bipolar I
Bipolar I disorder includes both manic and mixed episodes. According to the "Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision," the average age of onset is 20 and the time between episodes decreases with age. There is a strong genetic link for this disorder. Bipolar I disorder also increases the risk of bipolar II and major depressive disorder for individuals with first-degree relatives who have bipolar I disorder.
Bipolar II
Bipolar II disorder includes major depressive episodes and at least one hypomanic episode. The recurrence of major depressive episodes tends to overshadow periods of hypomania. This can lead to misdiagnosis, since breaks in depression can be few and far between and therefore not the focus of the problem a patient presents to a physician. In addition, borderline personality disorder frequently co-exists in patients with bipolar II disorder. In the July 2009 edition of "Psychiatric Times", Dr. Marianne Goodman, Dr. Jae Yeon Jeong and Dr. Joseph Triebwasser explain that distinguishing between borderline personality disorder and bipolar II disorder is difficult because emotional instability, irritable mood and impulsive behavior are symptomatic of both.
Cyclothymia
Cyclothymia disorder is defined by numerous fluctuations in mood from depressed to hypomanic. Symptoms of depression and hypomania are experienced on and off for a minimum of two years, but never meet the criteria for a major depressive, manic or mixed episode. Cyclothymia is typically diagnosed in adolescence or early adulthood. An estimated 50 to 75 percent of patients develop this disorder between the ages of 15 and 25, according to the "Encyclopedia of Mental Disorders." A diagnosis of cyclothymia increases the risk of later developing bipolar I or II disorder.
Bipolar NOS
Disorders with bipolar features that do not meet the criteria for cyclothymia or bipolar I or II disorder are called bipolar disorders not otherwise specified, or NOS. One example is a patient who reports symptoms of mania and depression that alternate at a rapid pace over the course of two to three days. Another example is a patient who experiences hypomanic episodes in the absence of depressive symptoms.
References
- "Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR); American Psychiatric Association; 2000
- MindDisorders.com: Cyclothymia Disorder
- "Psychiatric Times"; Borderline Personality Disorder and Bipolar Disorder--Distinguishing Features of Clinical Diagnosis and Treatment; Dr. Marianne Goodman, Dr. Jae Yeon Jeong and Dr. Joseph Triebwasser; July 2009
