Bipolar disorder is a mental illness characterized by periods of depression and elevated mood. It is caused by both genetic and environmental factors that result in abnormalities in brain structure and function. The symptoms of bipolar disorder include nervousness, anxiety, sadness, talking very fast, inability to relax or sleep, being overly active, and thoughts of death or suicide. It is important to diagnose and treat bipolar disorder early through medication and therapy in order to prevent suicide, substance abuse, relationship problems, and work issues. Famous people who are known to have bipolar disorder include Vincent van Gogh, Elizabeth Taylor, Britney Spears, and Catherine Zeta-Jones.