Causes
There is no single, proven cause of bipolar disorder, but research suggests that it is the result of abnormalities in the way some nerve cells in the brain function or communicate. Researchers also believe that there is a definite genetic link (family history) in which there is a higher risk for people who have a parent or full sibling (i.e., a first-degree relative) with bipolar disorder.
Whatever the precise nature of the cause of bipolar disorder, it clearly makes people with the disorder more vulnerable to emotional and physical stresses. As a result, upsetting life experiences, alcohol, illicit drug use, lack of sleep, or other stresses can trigger episodes of illness, even though these stresses do not actually cause the disorder.
Bipolar disorder is not the fault of the person suffering from it and is not the result of a "weak" or unstable personality. Rather, bipolar disorder is a treatable medical condition.