There's been a huge amount of material on manic-depression (especially the
latter phase recently), based on recent research--most of which can be found
via the previously mentioned posts.  Two pop works that explore the state
(not really "madness" in any technical sense, I believe) are William Styron's
book on his own bout with depression (the title is something like "Darkness
of Night") and "Listening to Prozac," which explores questions raised by the
most popular treatment for the condition.  (There's also a newer book that
answers that called something like "Talking Back to Prozac").
 
--Don Larsson, Mankato State U., MN