I had one study who became a witness. He had intense OCD causing panic attacks. I would get calls at 1 am where he was having a panic attack. He worked in a fast food place and was convinced he got a drop of blood in someone's food from a scratch or small cut and was freaked Jehober would destroy him at the big "A". I had to talk him down. It was exhausting. Eventually he pio-nerd for awhile. (Just like his teacher, lol) He faded the whole Witness thing. Nice guy but really effected.
I didn't have a lot of tolerance for crazies. Always passed them on to others more "empathetic", actually "desperate" for a study. I knew they wouldn't last long and would take gallons of gas to hunt down. Wasn't worth it.