What is bipolar disorder?
Bipolar disorder, also known as manic depressive illness, is characterised by recurrent episodes of mania and major depression. An affected person's mood can vary from excessively elated mood (mania) to very low mood (depression). In between episodes, mood is often normal, although in some people remains rather unstable.
The frequency and severity of mood swings varies. Some people have milder forms of the disorder and some people are more severely affected. Many people with bipolar disorder have long periods of normal mood when they are unaffected by their illness. Others experience rapidly changing moods or persistent low moods that have a marked effect on their quality of life.
Although manic and depressive mood swings are the most common, sometimes mixed states occur in which a person experiences symptoms of mania and depression at the same time. This often happens when the person is moving from a period of mania to one of depression. However for some people the mixed state appears to be the usual form of episode.
How common is bipolar disorder?
Bipolar disorder affects about 1 in 100 people and is now recognised to be one of the most important causes of disability worldwide.
When does bipolar disorder begin?
Bipolar disorder typically begins before the age of 30, but may begin at any age.
How is bipolar disorder diagnosed?
There is no physical test to diagnose bipolar disorder and so the diagnosis is made on the basis of the nature and course of the symptoms The diagnosis is based on an episode of mania (see above) or hypomania (where symptoms are similar to manic symptoms but less severe). People affected also usually suffer from episodes of low mood. A characteristic feature of bipolar disorder is that the disorder goes in cycles - over time a person will have periods of elevated mood, normal mood and depressed mood. In its early stages, bipolar disorder may be difficult to recognise, and may appear to be a different kind of problem. For example, the problem may first appear to be due to alcohol or drug use, or it may present as difficulties at school or work. After a diagnosis has been made some people realise that they have been suffering from bipolar disorder for many years - often without knowing what was wrong with them. A person may also experience a number of episodes of depression prior to experiencing a manic episode and may have been diagnosed as having unipolar depressive disorder (a mood disorder in which there are only depressive episodes.
What causes bipolar disorder?
The cause of bipolar disorder is not known but it is likely that it is caused by a number of factors. It tends to run in families and so genes may play a part - perhaps by altering the brain's chemistry. However despite vigorous research efforts, a specific genetic defect associated with the illness has not yet been detected. Early in the illness, stressful events (such as loss of a loved one or childbirth) may precipitate an episode of mania or depression in someone who is vulnerable but after some years the link between stress and episodes seems to weaken.
Page last edited: 07 May 2008
