Interesting interesting, I wouldn't be surprised regarding your parasite hypothesis. I've also read about the D connection as well.
There are two well known onset age ranges which interestingly coincide with steep hormone fluctuations: 1. late teens early adult, and also, 2. menopause age (coinciding with a drop in estrogen).
The drugs make overall health worse, especially in terms of quick degeneration of gastointistinal health; its a well known fact now that people taking these anti psychotic drugs on a a daily basis die 10-20 years earlier than the rest of us due to the drugs stuff up your small bowel and colon. :-( so we really need to find out other ways of helping.