I haven't read all the posts on here, but from what I have read, it certainly has a lot to do with the fact that the JW community is very insular. Also the high standards that are expected create feelings of guilt and never being good enough.
When I first became a witness, after about the first year, I suffered terribly from what I would call very low mood.I even wished I was dead at that time.
Looking back I now realise it was a mixture of things. I dropped all my 'worldly' friends. I used to go out socialising every weekend as had many friends. I began drinking at home. After a year and a half, I fell into a bit of trouble for which I was privately reproved. Little did I Know back then I was marked. I was living on my own and as a young man I was never invited out by witnesses my own age despite the fact it was a large congregation. I felt so lonely and isolated. I mean can you imagine not going out at the weekends with any friends for well over a year. It truly sucked. That period of my life still angers me to this day.
It's only years later, knowing how Watchtower works, knowing their policies by means of the flock book and getting a full sense of their teachings that I realised I was part of a high control religious group.
I feel sorry for those experiencing depression and thoughts of suicide. There is light at the end of the tunnel. Just live your life and be yourself. Don't let a group of men in their ivory tower pull you down. Stand up an be the person you should be.