More specifically,
mental illness and creativity are thought to be related. In fact,
according to wikipedia, it's bipolar disorder that's most closely linked with creativity. I was pretty shocked to find out that many famous people have bipolar (a lot of them seem to be in the arts): Robin Williams, Jim Carey, Drew Carey, Axl Rose, Kurt Cobain, Francis Ford Coppola, Buzz Aldrin, Ted Turner. Another interesting thing about bipolar disorder is that people who have it are often very goal-oriented and driven to succeed. Coupled with talent and intelligence, this explains the huge list of high achievers who have bipolar.