In patients who have mania, the delusions are consistent with their grandiose ideas and schemes but may also be paranoid. Research has shown that genetic factors play a significant role in the etiology of bipolar disorder. Biochemical, neurophysiologic, and sleep abnormalities also have been reported, but none seems specific to bipolar disorder. It is not known how recurrent unipolar depression, bipolar I disorder, and bipolar II disorder are related. In addition, many studies identify bipolar patients but do not specify whether the patient is in the depressive, manic, or mixed state, much less whether the patient is manic or hypomanic when studied.
Bipolar disorder is a recurring illness.
A few people are lucky enough to have only two or three episodes, but the average patient has more than 10. Studies have found that the depressive episodes in bipolar disorder are shorter than the depressive episodes in unipolar illness. Unfortunately, however, some bipolar patients have chronic depressions. Related to these two distinct illnesses is cyclothymia, a condition in which patients have mood swings, but the swings are not as extreme as those in mania and depression. Another related condition is hyperthymic temperament, seen in patients who have recurrent depression.