The Reiki Cafe 

I did a quick search at goole scholar

http://scholar.google.com/scholar?q=reiki+mental+illness&ie=...

Much of what you find with these searches are abstracts and you have to pay for the full text but there is information to be found that doesn't have to be paid for. Don't know if there is anything you would find useful but maybe it is worth a look

Walk in beauty,
Rebecca