Genetic factors contribute substantially to the likelihood of developing bipolar disorder, and environmental factors are also implicated. Bipolar disorder is often treated with mood stabilizing medications and, sometimes, other psychiatric drugs. Psychotherapy also has a role, often when there has been some recovery of the subject's stability. In serious cases, in which there is a risk of harm to oneself or others, involuntary commitment may be used. These cases generally involve severe manic episodes with dangerous behavior or depressive episodes with suicidal ideation. There are widespread problems with social stigma, stereotypes, and prejudice against individuals with a diagnosis of bipolar disorder. People with bipolar disorder exhibiting psychotic symptoms can sometimes be misdiagnosed as having schizophrenia, another serious mental illness.
The current term "bipolar disorder" is of fairly recent origin and refers to the cycling between high and low episodes (poles). A relationship between mania and melancholia had long been observed, although the basis of the current conceptualisation can be traced back to French psychiatrists in the 1850s. The term "manic-depressive illness" or psychosis was coined by German psychiatrist Emil Kraepelin in the late nineteenth century, originally referring to all kinds of mood disorder. German psychiatrist Karl Leonhard split the classification again in 1957, employing the terms unipolar disorder (major depressive disorder) and bipolar disorder.
Bipolar disorder is a condition in which people experience abnormally elevated (manic or hypomanic) and, in many cases, abnormally depressed states for periods of time in a way that interferes with functioning. Not everyone's symptoms are the same, and there is no simple physiological test to confirm the disorder. Bipolar disorder can appear to be unipolar depression. Diagnosing bipolar disorder is often difficult, even for mental health professionals. What distinguishes bipolar disorder from unipolar depression is that the affected person experiences states of mania and depression. Often bipolar is inconsistent among patients because some people feel depressed more often than not and experience little mania whereas others experience predominantly manic symptoms. Additionally, the younger the age of onset—bipolar disorder starts in childhood or early adulthood in most patients—the more likely the first few episodes are to be depression. Because a bipolar diagnosis requires a manic or hypomanic episode, many patients are initially diagnosed and treated as having major depression.
Signs and symptoms of the depressive phase of bipolar disorder include persistent feelings of sadness, anxiety, guilt, anger, isolation, or hopelessness; disturbances in sleep and appetite; fatigue and loss of interest in usually enjoyable activities; problems concentrating; loneliness, self-loathing, apathy or indifference; depersonalization; loss of interest in sexual activity; shyness or social anxiety; irritability, chronic pain (with or without a known cause); lack of motivation; and morbid suicidal ideation. In severe cases, the individual may become psychotic, a condition also known as severe bipolar depression with psychotic features. These symptoms include delusions or, less commonly, hallucinations, usually unpleasant. A major depressive episode persists for at least two weeks, and may continue for over six months if left untreated.
The causes of bipolar disorder likely vary between individuals. Twin studies have been limited by relatively small sample sizes but have indicated a substantial genetic contribution, as well as environmental influence. For bipolar I, the (probandwise) concordance rates in modern studies have been consistently put at around 40% in monozygotic twins (same genes), compared to 0 to 10% in dizygotic twins. A combination of bipolar I, II and cyclothymia produced concordance rates of 42% vs 11%, with a relatively lower ratio for bipolar II that likely reflects heterogeneity. The overall heritability of the bipolar spectrum has been put at 0.71. There is overlap with unipolar depression and if this is also counted in the co-twin the concordance with bipolar disorder rises to 67% in monozigotic twins and 19% in dizigotic. The relatively low concordance between dizygotic twins brought up together suggests that shared family environmental effects are limited, although the ability to detect them has been limited by small sample sizes.
Abnormalities in the structure and/or function of certain brain circuits could underlie bipolar. Two meta-analyses of MRI studies in bipolar disorder report a increase in the volume of the lateral ventricles, globus pallidus and increase in the rates of deep white matter hyperintensities.
The "kindling" theory asserts that people who are genetically predisposed toward bipolar disorder can experience a series of stressful events, each of which lowers the threshold at which mood changes occur. Eventually, a mood episode can start (and become recurrent) by itself. There is evidence of hypothalamic-pituitary-adrenal axis (HPA axis) abnormalities in bipolar disorder due to stress.
Other brain components which have been proposed to play a role are the mitochondria, and a sodium ATPase pump, causing cyclical periods of poor neuron firing (depression) and hypersensitive neuron firing (mania). This may only apply for type one, but type two apparently results from a large confluence of factors. Circadian rhythms and melatonin activity also seem to be altered.
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. There is fairly consistent evidence from prospective studies that recent life events and interpersonal relationships contribute to the likelihood of onsets and recurrences of bipolar mood episodes, as they do for onsets and recurrences of unipolar depression. There have been repeated findings that between a third and a half of adults diagnosed with bipolar disorder report traumatic/abusive experiences in childhood, which is associated on average with earlier onset, a worse course, and more co-occurring disorders such as PTSD. The total number of reported stressful events in childhood is higher in those with an adult diagnosis of bipolar spectrum disorder compared to those without, particularly events stemming from a harsh environment rather than from the child's own behavior. Early experiences of adversity and conflict are likely to make subsequent developmental challenges in adolescence more difficult, and are likely a potentiating factor in those at risk of developing bipolar disorder.
Criteria and subtypes
There is no clear consensus as to how many types of bipolar disorder exist. In DSM-IV-TR and ICD-10, bipolar disorder is conceptualized as a spectrum of disorders occurring on a continuum. The DSM-IV-TR lists three specific subtypes and one for non-specified:
- Bipolar I disorder : One or more manic episodes. Subcategories specify whether there has been more than one episode, and the type of the most recent episode. A depressive or hypomanic episode is not required for diagnosis, but it frequently occurs.
- Bipolar II disorder : No manic episodes, but one or more hypomanic episodes and one or more major depressive episode. However, a bipolar II diagnosis is not a guarantee that they will not eventually suffer from such an episode in the future. Hypomanic episodes do not go to the full extremes of mania (i.e., do not usually cause severe social or occupational impairment, and are without psychosis), and this can make bipolar II more difficult to diagnose, since the hypomanic episodes may simply appear as a period of successful high productivity and is reported less frequently than a distressing, crippling depression.
- Cyclothymia : A history of hypomanic episodes with periods of depression that do not meet criteria for major depressive episodes. There is a low-grade cycling of mood which appears to the observer as a personality trait, and interferes with functioning.
- Bipolar Disorder NOS (Not Otherwise Specified) : This is a catchall category, diagnosed when the disorder does not fall within a specific subtype. Bipolar NOS can still significantly impair and adversely affect the quality of life of the patient.
There are a number of pharmacological and psychotherapeutic techniques used to treat bipolar disorder. Individuals may use self-help and pursue recovery.
Hospitalization may be required especially with the manic episodes present in bipolar I. This can be voluntary or (if mental health legislation allows and varying state-to-state regulations in the USA) involuntary (called civil or involuntary commitment). Long-term inpatient stays are now less common due to deinstitutionalization, although these can still occur. 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 Assertive Community Treatment team, supported employment and patient-led support groups, intensive outpatient programs. These are sometimes referred to partial-inpatient programs.
The mainstay of treatment is a mood stabilizers such as lithium carbonate or lamotrigine. Lamotrigine has been found to be best for preventing depressions, while lithium is the only drug proven to reduce suicide in people with bipolar disorder. These two drugs comprise several unrelated compounds which have been shown to be effective in preventing relapses of manic, or in the one case, depressive episodes. The first known and "gold standard" mood stabilizer is lithium, while almost as widely used is sodium valproate, also used as an anticonvulsant. Other anticonvulsants used in bipolar disorder include carbamazepine, reportedly more effective in rapid cycling bipolar disorder, and lamotrigine, which is the first anticonvulsant shown to be of benefit in bipolar depression. Depending on the severity of the case, anti-convulsants may be used in combination with lithium-based products or on their own.
Atypical antipsychotics have been found to be effective in managing mania associated with bipolar disorder. Antidepressants have not been found to be of any benefit over that found with mood stabilizers.
Omega 3 fatty acids, in addition to normal pharmacological treatment, may have beneficial effects on depressive symptoms, although studies have been scarce and of variable quality. The effectiveness of topiramate is unknown.
Prognosis depends on many factors such as the right medicines and dosage, comprehensive knowledge of the disease and its effects; a positive relationship with a competent medical doctor and therapist; and good physical health, which includes exercise, nutrition, and a regulated stress level. There are other factors that lead to a good prognosis, such as being very aware of small changes in a person's energy, mood, sleep and eating behaviors.
A recent 20-year prospective study on bipolar I and II found that functioning varied over time along a spectrum from good to fair to poor. During periods of major depression or mania (in BPI), functioning was on average poor, with depression being more persistently associated with disability than mania. Functioning between episodes was on average good — more or less normal. Subthreshold symptoms were generally still substantially impairing, however, except for hypomania (below or above threshold) which was associated with improved functioning.