A story from NY Newsday queries professional psychologists about the mental health of Batman and the likely causes of his mental instability.
Batman is a fascinating character, not least because his mind and motivations have become an integral plot device in many films and graphic novels.
In fact, the portrayal of madness in the Batman universe is a topic I have tackled myself, in a past article for kuro5hin.org
Almost uniquely for such a popular genre, the plots of Batman revolve around mental illness, because, in addition to Batman’s own troubled thoughts, almost all the criminals are depicted as insane.
It is likely that Batman is both a mirror for our own stereotypes of madness, as well as a medium through which children get some of their first impressions of mental illness.
Link to ‘Is he really batty?’ from NY Newsday
Link to ‘Madness in Gotham’ from kuro5hin.org
Mind Hacks 
have you read Batman:Prey? Late 80s/90s storyline set back in Year 1 territory where he goes nine rounds with an insane psychiatrist and an obsessed cop. Very good stuff.