Bipolar disorders
Bipolar disorder is a chronic psychiatric illness characterised by recurrent mood disorders; it was previously known as manic-depressive psychosis.
Bipolar disorder is characterised by manic and depressive episodes, which may alternate, although patients show a predominance of one of the two states. The exact cause is unknown, but heredity, changes in brain neurotransmitters and psychosocial factors may be involved.
Bipolar disorder begins with an acute phase and is followed by alternating relapses and remissions. Remissions are often complete, but many patients have residual symptoms, and for some their ability to work is severely impaired. Relapses are episodes of more intense symptoms with mania, depression, hypomania or a mixture of depressive and manic symptoms.
Episodes last from a few weeks to 3 to 6 months; depressive episodes generally last longer than manic or hypomanic episodes.
The length of the cycles between the onset of one episode and the next varies from patient to patient. Some patients have infrequent episodes, sometimes just a few in their lifetime, while others have rapid-cycle forms (usually defined as ≥ 4 episodes/year). Only a minority alternate between mania and depression at each cycle; in most cases, one or the other predominates.
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