Musicians with Bipolar Disorder

Bipolar disorder is a diagnosis in psychiatry referring to periods of extreme, often inappropriate, and sometimes unpredictable mood states.

Many famous people are believed to have been affected by bipolar disorder (formerly known as manic depression), based on evidence in their own writings and contemporaneous accounts by those who knew them.

It is often suggested that genius (or, at least, creative talent) and mental disorder are linked and numerous studies have suggested that there is a correlation between creativity and bipolar disorder, although it is unclear what the relationship is between the two.
http://www.indie-planet.net/news/musicians-with-bipolar-disorder/