Bipolar disorder is also called manic-depressive. Bi-, from the Latin bis (twice); polar from the Greek polos (pivot point), so: bipolar. It is the name of a disease that has two voting poles; a manic and a depressive one with between a normal mood.
This disorder occurs in approximately 2-4% of the general population and is characterized by extremes in mood and activity.
In a mania, you are generally exuberant and energetic.
In a depression you usually just withdrawn yourself from the world and are very passive.
These mood swings can have major consequences for the emotional and social functioning of the patient. And also for his or her environment (partners, family, friends or colleagues). In the extremes of mood you often have to go to a psychiatric hospital. The multiplicity of the disease complicates a early diagnosis and a adequate treatment. (Source: VMDB and KenBis).