Julia - it's the same here in the States. And it's most likely the result of so much negativity in our lives. As JW's we are conditioned to be judgemental, suspicious, afraid of criticism or reproof, and competitive. That in itself will make a person neurotic. Add to that list - personal disappointments, fear of displeasing the control group, the persecution complex, and suppression of personal hopes/desires/dreams and people do become ill - on all levels.
I've noticed that during their transitions out of the congregation, many become involved in positive activities. We begin to exercise, watch our diet, take up some sort of hobby, even change careers or go back to school. Good things!
At the saying goes...."misery loves company." How true with JW's...