Lol..scary eh.....all I'll say it's happened in Japan and I'm personally aware of two cases. Seems some practioners of arts such as tai-chi etc have had very real problems with this kind of thing and very few can help. You won't find much documented though naturally
I will say no one in aikido that I know of will be able to help anyone that messes up....so be careful what you do...that's why dojo practise is always the safest way. Some people are advocating certain things without possibly understanding/explaining what can go wrong. Too many people are merely accepting without really questioning or knowing much at all....you wouldn't really take a drug without knowing the side effects would you? take care is all I can say to everyone.
People in China doing internals etc are known to have become mentally sick...some that appeared strong in youth have suffered later. Some accomplished people on this site have also indicated that the mental state of some who went before in aikido have not always been so great....I won't go further to highlight anyone.
Where do I get my info?. I'm very lucky to know a very senior Japanese practioner/healer outside of aikido who has had to deal with this kind of thing. I won't give info on him and he probably won't be happy to see you if you mess up...be warned..