James Beckford shares a similar view to mine that Jehovah's witnesses would not have allowed schizophrenics to remain in the organisation.
Guys I appreciate that this is just one persons experience, but in my old congregation there was a baptised sister who couldn't give coherent answers, there was obviously some serious issues. She seemed to me to suffer with paranoia, too. The attitude of other Jw's was that 'jehovah had obviously seen something in her heart' and drawn her to the society.
I realize that not all congs would be so accepting. She was included in all service arrangements and invited to all the main 'get togethers'. I'm not sure what happened to her as I was only a teen at the time.