I hadn't heard of that association, Talesin, but I will do some research. That's amazing what it has done for your friend, but not at all surprising. I've been collecting bits and pieces of those kinds of stories for years with the intention of writing my own book one day on the topic.
The University of Alberta has an interesting program "Arts & Humanities in Health & Medicine". They have links to a lot of library resources and you can join their mail list if you are interested in that sort of thing. I also just came across this: http://www.musicophilia.com/music_links.htm, which looks like a must-read book for me, Oliver Sacks Musicophilia. Also this link to some research seems worthwhile: http://www.scientificamerican.com/blog/post.cfm?id=new-research-explores-how----and-wh-2009-07-06
There is a lot of anecdotal experience, like your own, but I find you have to weed through a lot of "personal opinion" type articles to find the actual scientific research-based information.