Defining Bipolar Disorders

Bipolar disorder (commonly referred to as manic-depression) is a mood disorder characterized by periods of elevated mood and periods of depression. The elevated mood is significant and is known as mania or hypomania depending on the severity or whether there is psychosis. Both manic and depressive episodes are so intense that they interfere with everyday life. Between cycles of manic and depressive states, the individual will often experience normal functioning. The risk of suicide among those with the disorder is high at greater than 6% over 20 years, while self harm occurs in 30%–40% of patients. Other mental health issues such as anxiety disorders and substance use disorders are commonly associated.

DSM-5 Diagnostic Criteria

While all of us feel highs and lows and may even experience euphoria and depression, bipolar disorder is a much more severe, debilitating clinical disorder. The "bipolar spectrum" refers to the range in which these alternating moods may occur and includes bipolar I, bipolar II, cyclothymia, and other specified bipolar and related disorder. For all of these diagnoses to be made, the symptoms must indicate a major change from the person's typical mood. 

Bipolar I

A diagnosis of bipolar I requires the occurrence of one or more manic or mixed episodes that last for at least a week (though less if hospitalization is required). A manic episode is a distinct period of elevated or irritable mood, which can take the form of euphoria. People with mania commonly experience an increase in energy and a decreased need for sleep, with many often getting as little as three or four hours of sleep per night. Some can go days without sleeping. A person experiencing mania may exhibit pressured speech, racing thoughts, low attention span, high distractibility, or poor judgment; they may engage in risky behavior or become aggressive. As mania becomes more severe, individuals begin to behave erratically and impulsively, often making poor decisions due to unrealistic ideas about the future. Many people experience psychotic symptoms. 

A mixed episode is a condition during which symptoms of mania and depression occur simultaneously. Typical examples include weeping during a manic episode, experiencing racing thoughts during a depressive episode, or thinking grandiose thoughts while at the same time feeling like a failure. Mixed states are often the most dangerous period of mood disorders, during which the risks of substance abuse, panic disorder, suicide attempts, and other complications significantly increase.

A major depressive episode is not required for diagnosis of bipolar I, although it frequently occurs. The depressive phase includes persistent feelings of sadness, anxiety, guilt, anger, isolation, hopelessness, disturbances in sleep and appetite, fatigue, loss of interest in usually enjoyable activities, problems concentrating, loneliness, self-loathing, apathy, and/or indifference. A major depressive episode persists for at least two weeks.

Bipolar II

In order for bipolar II to be diagnosed, the person must not have experienced a full manic episode; however, one or more hypomanic episodes and one or more major depressive episodes are required to merit diagnosis. Hypomanic episodes are a milder version of mania, defined by a mild to moderately elevated mood, optimism, pressure of speech or activity, and decreased need for sleep. Generally, hypomania does not inhibit functioning as mania does, and may even increase productivity. Bipolar II can be more difficult to diagnose because the hypomanic episodes may simply appear as a period of successful high productivity. Hypomania also tends to be reported less frequently than a distressing, crippling depression, and so people with bipolar II are often misdiagnosed with major depressive disorder.

Cyclothymic Disorder

Cyclothymia is a milder version of bipolar. A diagnosis requires that a person experience hypomanic episodes with periods of a milder form of depression, known as dysthymia, for at least 2 years. Neither the hypomanic or dysthymic episodes can meet the criteria for bipolar I or II. There is a low-grade cycling of mood which typically appears to the observer as a personality trait and interferes with functioning.

Other Specified Bipolar and Related Disorder

Previously known as bipolar disorder NOS (not otherwise specified), this is a catch-all category that is diagnosed when the disorder does not fall within a specific subtype of bipolar (for example, if the time requirements for symptoms are not met but the symptoms are still pervasive and disruptive). These disorders can still significantly impair and adversely affect the quality of life of the patient.

Disruptive Mood Dysregulation Disorder

While not officially on the spectrum of bipolar disorders, the DSM-5 recently added the diagnosis of disruptive mood dysregulation disorder (DMDD). A psychiatric mood disorder in children, it is characterized by persistently irritable or angry mood with recurrent, severe temper outbursts. The symptoms of DMDD resemble those of other childhood disorders, notably attention deficit hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), and bipolar disorder in children. Children with DMDD are at risk for depression in later childhood and adolescence.

Etiology

It is estimated that roughly 1% of the adult population suffer from bipolar I, a further 1% suffer from bipolar II or cyclothymia, and somewhere between 2% and 5% percent suffer from "sub-threshold" forms of bipolar disorder. Bipolar disorders have been shown to have a strong genetic and biological basis. The possibility of getting bipolar disorder when one parent is diagnosed with it is 15%–30%; risk when both parents have it is 50%–75%. The rate of concordance for bipolar disorder is higher among identical twins than fraternal twins (67% vs. 16%, respectively), suggesting that genetic factors play a strong role in bipolar disorder (Merikangas et al., 2011).

People with bipolar disorders often have imbalances in certain neurotransmitters, particularly norepinephrine and serotonin (Thase, 2009). These neurotransmitters are important regulators of the bodily functions that are disrupted in mood disorders, including appetite, sex drive, sleep, arousal, and mood. Medications that are used to treat bipolar disorders (such as lithium) work to block norepinephrine activity at the synapses.

Evidence suggests that environmental factors play a significant role in the development and course of bipolar disorder and that individual psychosocial variables may interact with genetic dispositions. Abnormalities in the structure and/or function of certain brain circuits could underlie bipolar disorder; MRI studies report significant differences in brain composition between individuals with bipolar disorder and individuals without.

Brain composition and bipolar disorder

MRI studies indicate many compositional differences between brains of individuals with bipolar disorder and individuals without. This supports the idea that bipolar disorder is a confluence of both environmental and biological factors.

Treatment

Bipolar disorder is often treated with mood-stabilizing medications and psychotherapy. Typically, these two are used in conjunction. The medication with the best evidence thus far is lithium, which is effective for many people in treating acute manic episodes and preventing relapses (more so for manic than for depressive episodes). Other potentially effective medications include anticonvulsants and antipsychotics.

Hospitalization may be required, especially with the manic episodes present in bipolar I. Following (or in lieu of) a hospital admission, support services available can include drop-in centers, visits from members of a community mental-health team or an assertive community treatment (ACT) team, supported employment, patient-led support groups, and intensive outpatient programs. 

Psychotherapy is aimed at alleviating core symptoms, recognizing episode triggers, reducing negative expressed emotion in relationships, recognizing symptoms before full-blown recurrence, and practicing the factors that lead to maintenance of remission. Cognitive behavioral therapy, family-focused therapy, and psychoeducation have the most evidence for efficacy in regard to relapse prevention.