Borrowing from Wikipedia: "Some authors claim that Wilhelm (later William) Steinitz (1836-05-17, Prague – 1900-08-12, New York) contracted syphilis, so that this may have been a cause of the mental breakdowns he suffered in his last years. His chess activities had not yielded any great financial rewards, and he died a pauper in the Manhattan State Hospital (Ward island) of a heart attack. Steinitz is buried in the Cemetery of the Evergreens in Brooklyn, New York."
Did this guy actually go mad?