I INTRODUCTION
| PREVALENCE | | SYMPTOMS
| | CAUSES | | TREATMENT
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Bipolar Disorder, mental illness in which a person's mood alternates between extreme mania and depression. Bipolar disorder is also called manic-depressive illness. When manic, people with bipolar disorder feel intensely elated, self-important, energetic, and irritable. When depressed, they experience painful sadness, negative thinking, and indifference to things that used to bring them happiness.
These positron emission tomography scans of the brain of
a person with bipolar disorder show the individual shifting from
depression, top row, to mania, middle row, and back to
depression, bottom row, over the course of 10 days. Blue and
green indicate low levels of brain activity, while red, orange, and
yellow indicate high levels of brain activity.
II PREVALENCE
Bipolar disorder is much less common than depression. In North America and Europe, about 1 percent of people experience bipolar disorder during their lives. Rates of bipolar disorder are similar throughout the world. In comparison, at least 8 percent of people experience serious depression during their lives. Bipolar disorder affects men and women about equally and is somewhat more common in higher socioeconomic classes. At least 15 percent of people with bipolar disorder commit suicide. This rate roughly equals the rate for people with major depression, the most severe form of depression.
Some research suggests that highly creative people-such as artists, composers, writers, and poets-show unusually high rates of bipolar disorder, and that periods of mania fuel their creativity. Famous artists and writers who probably suffered from bipolar disorder include poets Lord Byron and Anne Sexton, novelists Virginia Woolf and Ernest Hemingway, composers Peter Ilich Tchaikovsky and Sergey Rachmaninoff, and painters Amedeo Modigliani and Jackson Pollock. Critics of this research note that many creative people do not suffer from bipolar disorder, and that most people with bipolar disorder are not especially creative.
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III SYMPTOMS
Bipolar disorder usually begins in a person's late teens or 20s. Men usually experience mania as the first mood episode, whereas women typically experience depression first. Episodes of mania and depression usually last from several weeks to several months. On average, people with untreated bipolar disorder experience four episodes of mania or depression over any ten-year period. Many people with bipolar disorder function normally between episodes. In "rapid-cycling" bipolar disorder, however, which represents 5 to 15 percent of all cases, a person experiences four or more mood episodes within a year and may have little or no normal functioning in between episodes. In rare cases, swings between mania and depression occur over a period of days.
In another type of bipolar disorder, a person experiences major depression and hypomanic episodes, or episodes of milder mania. In a related disorder called cyclothymic disorder, a person's mood alternates between mild depression and mild mania. Some people with cyclothymic disorder later develop full-blown bipolar disorder. Bipolar disorder may also follow a seasonal pattern, with a person typically experiencing depression in the fall and winter and mania in the spring or summer (see Seasonal Affective Disorder).
People in the depressive phase of bipolar disorder feel intensely sad or profoundly indifferent to work, activities, and people that once brought them pleasure. They think slowly, concentrate poorly, feel tired, and experience changes-usually an increase-in their appetite and sleep. They often feel a sense of worthlessness or helplessness. In addition, they may feel pessimistic or hopeless about the future and may think about or attempt suicide. In some cases of severe depression, people may experience psychotic symptoms, such as delusions (false beliefs) or hallucinations (false sensory perceptions). See Psychosis.
In the manic phase of bipolar disorder, people feel intensely and inappropriately happy, self-important, and irritable. In this highly energized state they sleep less, have racing thoughts, and talk in rapid-fire speech that goes off in many directions. They have inflated self-esteem and confidence and may even have delusions of grandeur. Mania may make people impatient and abrasive, and when frustrated, physically abusive. They often behave in socially inappropriate ways, think irrationally, and show impaired judgment. For example, they may take airplane trips all over the country, make indecent sexual advances, and formulate grandiose plans involving indiscriminate investments of money. The self-destructive behavior of mania includes excessive gambling, buying outrageously expensive gifts, abusing alcohol or other drugs, and provoking confrontations with obnoxious or combative behavior.
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IV CAUSES
The genes that a person inherits seem to have a strong influence on whether the person will develop bipolar disorder. Studies of twins provide evidence for this genetic influence. Among genetically identical twins where one twin has bipolar disorder, the other twin has the disorder in more than 70 percent of cases. But among pairs of fraternal twins, who have about half their genes in common, both twins have bipolar disorder in less than 15 percent of cases in which one twin has the disorder. The degree of genetic similarity seems to account for the difference between identical and fraternal twins. Further evidence for a genetic influence comes from studies of adopted children with bipolar disorder. These studies show that biological relatives of the children have a higher incidence of bipolar disorder than do people in the general population. Thus, bipolar disorder seems to run in families for genetic reasons.
Personal or work-related stress can trigger a manic episode, but this usually occurs in people with a genetic vulnerability. Other factors-such as prenatal development, childhood experiences, and social conditions-seem to have relatively little influence in causing bipolar disorder. One study examined the children of identical twins in which only one member of each pair of twins had bipolar disorder. The study found that regardless of whether the parent had bipolar disorder or not, all of the children had the same high 10-percent rate of bipolar disorder. This observation clearly suggests that risk for bipolar illness comes from genetic influence, not from exposure to a parent's bipolar illness or from family problems caused by that illness.
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V TREATMENT
Different therapies may shorten, delay, or even prevent the extreme moods caused by bipolar disorder. Lithium carbonate, a natural mineral salt, can help control both mania and depression in bipolar disorder. The drug generally takes two to three weeks to become effective. People with bipolar disorder may take lithium during periods of relatively normal mood to delay or prevent subsequent episodes of mania or depression. Common side effects of lithium include nausea, increased thirst and urination, vertigo, loss of appetite, and muscle weakness. In addition, long-term use can impair functioning of the kidneys. For this reason, doctors do not prescribe lithium to bipolar patients with kidney disease. Many people find the side effects so unpleasant that they stop taking the medication, which often results in relapse. See Lithium.
From 20 to 40 percent of people do not respond to lithium therapy. For these people, two anticonvulsant drugs may help dampen severe manic episodes: carbamazepine (Tegretol) and valproate (Depakene). The use of traditional antidepressants to treat bipolar disorder carries risks of triggering a manic episode or a rapid-cycling pattern.
(See Depression)
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