|This disorder is characterized by repeated (i.e. at least two) episodes in which the patient's mood and activity levels are significantly disturbed, this disturbance consisting on some occasions of an elevation of mood and increased energy and activity (mania or hypomania), and on others of a lowering of mood and decreased energy and activity (depression). Characteristically, recovery is usually complete between episodes, and the incidence in the two sexes is more nearly equal than in other mood disorders. As patients who suffer only from repeated episodes of mania are comparatively rare, and resemble (in their family history, premorbid personality, age of onset, and long-term prognosis) those who also have at least occasional episodes of depression, such patients are classified as bipolar.|
|Manic episodes usually begin abruptly and last for between 2 weeks and 4-5 months (median duration about 4 months). Depressions tend to last longer (median length about 6 months), though rarely for more than a year, except in the elderly. Episodes of both kinds often follow stressful life events or other mental trauma, but the presence of such stress is not essential for the diagnosis. The first episode may occur at any age from childhood to old age. The frequency of episodes and the pattern of remissions and relapses are both very variable, though remissions tend to get shorter as time goes on and depressions to become commoner and longer lasting after middle age.|
|Although the original concept of "manic-depressive psychosis" also included patients who suffered only from depression, the term "manic-depressive disorder or psychosis" is now used mainly as a synonym for bipolar disorder.|
* manic-depressive illness, psychosis or reaction
Although the most typical form of bipolar disorder consists of alternating manic and depressive episodes separated by periods of normal mood, it is not uncommon for depressive mood to be accompanied for days or weeks on end by overactivity and pressure of speech, or for a manic mood and grandiosity to be accompanied by agitation and loss of energy and libido. Depressive symptoms and symptoms of hypomania or mania may also alternate rapidly, from day to day or even from hour to hour. A diagnosis of mixed bipolar affective disorder should be made only if the two sets of symptoms are both prominent for the greater part of the current episode of illness, and if that episode has lasted for a least 2 weeks.
Three degrees of severity are specified here, sharing the common underlying characteristics of elevated mood, and an increase in the quantity and speed of physical and mental activity. All the subdivisions of this category should be used only for a single manic episode. If previous or subsequent affective episodes (depressive, manic, or hypomanic), the disorder should be coded under bipolar affective disorder.