I think they attract each other for a lot of reasons. The Dub love-bombing attracts those who are social misfits due to their illness plus they are often superreligious themselves, or go through periods of it.
When I was a child there was a young man who was most likely bipolar who was one of those "instant" conversions and baptisms. When he started to act funny at the meetings and with some of the cong members he was DFed. He shot himself a couple of weeks later. He couldn't have a JW funeral and I was told he wouldn't make it into the new system since he was DFed and a suicide. I cried and cried--he had been kind to me.
Later I knew a young man who had to take a lot of meds and was convinced by some of the sisters who were into health foods and juices that he could throw away his pills if he would just eat right. Also he was a fairly recent convert so he was led to believe that the borg was all he needed, you know, prayer, meetings, field service, blah, blah, blah. He went off the deep end, got all crazy, got DFed, and died in a skid row hotel room.
I also knew of a bizarre JW in my parent's cong after I was out who used to do his streetwork in the middle of the night in front of the all night market--scaring people half to death 'cause he looked really strange and just stood there waving the Watchtowers at them. The elders had to make him stop.