Bipolar disorder, also known as manic-depressive illness, is a treatable illness that causes extreme swings in mood, thought, energy, and behavior. This medical problem is not due to personal weakness or a character flaw. The mood swings associated with bipolar disorder are different from the average ups and downs of everyday life and are often associated with psychotic symptoms such as hallucinations, delusions, or disorders of thought. They can result in damaged relationships, poor job or school performance, and even suicide. When treated appropriately, people with this illness can lead full and productive lives.

Bipolar disorder affects an estimated 1%-3% of American adults (18 and older). Bipolar disorder typically develops in late adolescence or early adulthood. However, some people have their first symptoms during childhood, and some develop symptoms late in life. Bipolar disorder is a long-term illness that must be carefully managed throughout a person's life.

The cause of bipolar disorder is not known. Bipolar disorder tends to run in families. Specific genes may play a role, but it is not caused by one single gene. Additional factors, possibly stressors at home, work, or school, are believed to be involved in its onset.

People with bipolar disorder are at increased risk for suicide, substance abuse, and dangerous behaviors such as reckless driving and sexual promiscuity. Anxiety disorders, such as post-traumatic stress disorder and obsessive-compulsive disorder , may be common in people with bipolar disorder.