Bipolar disorder, also known as manic-depressive illness, is a mental health condition that causes unusual shifts in mood, energy, activity levels, and the ability to carry out day-to-day tasks. Symptoms of bipolar disorder are often severe. They are different from the normal ups and downs that everyone goes through from time to time. Bipolar disorder symptoms can result in damaged relationships, poor job or school performance, and even suicide. But bipolar disorder can be treated, and people with this illness can lead full and productive lives.
Scientists are studying the possible causes of bipolar disorder. Most scientists agree that there is no single cause. Rather, many factors likely act together to produce the illness or increase risk.
Bipolar disorder tends to run in families. Some research has suggested that people with certain genes are more likely to develop bipolar disorder than others. Children with a parent or sibling who has bipolar disorder are much more likely to develop the illness, compared with children who do not have a family history of bipolar disorder. However, most children with a family history of bipolar disorder will not develop the illness.
Scientists are also studying illnesses with similar symptoms such as depression and schizophrenia to identify genetic differences that may increase a person’s risk for developing bipolar disorder. Finding these genetic “hotspots” may also help explain how environmental factors can increase a person’s risk.
But genes are not the only risk factor for bipolar disorder. Studies of identical twins have shown that the twin of a person with bipolar illness does not always develop the disorder, despite the fact that identical twins share all of the same genes. Research suggests that factors besides genes are also at work. It is likely that many different genes and environmental factors are involved. However, scientists do not yet fully understand how these factors interact to cause bipolar disorder.
Signs and Symptoms
People with bipolar disorder experience unusually intense emotional states that occur in distinct periods called “mood episodes.” Each mood episode represents a drastic change from a person’s usual mood and behavior. An overly joyful or overexcited state is called a manic episode, and an extremely sad or hopeless state is called a depressive episode. Sometimes, a mood episode includes symptoms of both mania and depression. This is called a mixed state. People with bipolar disorder also may be explosive and irritable during a mood episode. Extreme changes in energy, activity, sleep, and behavior go along with these changes in mood. Symptoms of bipolar disorder are described below.