What are the causes of bipolar disorder?

While the exact cause of bipolar disorder is not known, most scientists believe that bipolar disorder is likely caused by multiple factors that interact with each other to produce a chemical imbalance affecting certain parts of the brain.

Bipolar disorder often runs in families, and studies suggest a genetic component to the illness. A stressful environment or negative life events may interact with an underlying genetic or biological vulnerability to produce the disorder.

There are other possible “triggers” of bipolar episodes: the treatment of depression with an antidepressant medication may trigger a switch into mania, sleep deprivation may trigger mania, or hypothyroidism may produce depression or mood instability. It is important to note that bipolar episodes can and often do occur without any obvious trigger.

Source: National Alliance on Mental Illness, www.nami.org