While the exact cause of Bipolar Disorder is unknown, it is largely believed that the cause is a combination of genetics and brain structure and function, according to the National Institute of Mental Health (NIMH)

“Bipolar disorder often runs in families, and research suggests this is mostly explained by heredity—people with certain genes are more likely to develop bipolar disorder than others. Many genes are involved, and no one gene can cause the disorder.”

“Research shows that the brain structure and function of people with bipolar disorder may differ from those of people who do not have bipolar disorder or other mental disorders.”