If You're Crazy And You Know It, Draw a Picture

This article links a variety of mental illnesses, most notably bi-polar disorder, to the creative condition.

"Experts say mental illness does not necessarily cause creativity, nor does creativity necessarily contribute to mental illness, but a certain ruminating personality type may contribute to both mental health issues and art."

It seems to me that it would be extraordinarily difficult to prove this kind of link, but I think there's something to it. You would too, if you knew some of the deranged geniuses that I know.

By the way - 'ruminating personality type' - excellent term.