Contact choir for people with dementia

Every once in a month i'm assisting my ex - colleague with her monthly choir session.
I play guitar flute or sometimes percussion instruments. Contact choir means that one can touch verry deeply , throught the expression of music , in the minds of people with living with dementia. It's not that they have to sing in tune , just being there is enough.
I post a link under to have an impression .
http://www.youtube.com/watch?v=3HERr1PBd70