Bipolar disorder refers to a group of mood disorders characterized by cyclical disturbances in mood, thought and behavior. It consists of alternating periods of elevated, expansive or irritable moods (manic episodes) and depressive episodes.
Manic episodes run on a spectrum from mild mania (hypomania) to psychotic or delirious states. Depressive episodes may range from milder, subclinical depression to depression severe enough to classified as major depression.
The severity of the manic and depressive episodes is a factor in determining the patient's specific diagnosis. Bipolar I disorder refers to patients who have had at least one episode of mania or mixed episodes (exhibiting symptoms of both depression and mania during the same period of time). Bipolar II disorder refers to patients who have had both hypomania and major depressive episodes. Cyclothymia refers to patients who have had chronic fluctuations between hypomania and subclinical depression.
Whether the patient has had a manic episode is a critical point in distinguishing bipolar disorder from major depressive disorder. For a patient to be diagnosed with bipolar disorder, he or she must have had an episode of mania that lasted for at least one week or an episode of hypomania that lasted for at least four days.
To learn more about bipolar disorder, please visit About.com: Bipolar.
Source:
Jacobson, James L. and Alan M. Jacobson. Psychiatric Secrets 2nd ed. Philadelphia: Hanley & Belfus, 2001.
