My 94 year old mom lives with us and she has had Alzheimer's for about 10 years. She reached the point several years ago where I am sure she does not know I am her daughter or that my kids are her grandkids. Oddly tho, this does not bother us - we are just so happy she is still around. She doesn't talk anymore but gets excited and does laugh about things we do. She is interested in everything that goes on around her - likes to watch out the window all day, looks thru mags, plays with "toys" etc. We have to feed her and change her etc. Just lately she has been unable to stand so have to lift her from bed to chair and vv. I know most people think it is so sad, esp for the families, but we are not sad about it - it is just as it is and we can live with that. I really don't believe that she knows that she can't remember. She just knows what she knows. We don't take her not knowing us personally or the fact she can't remember things. As one of my kids said, they can't remember their real early years - when I fed them, changed them, learning to walk etc but it does not make them sad that can't remember that - so they don't see the dif. Lots of my friends no longer have a parent and I am just happy and feel blessed that she is still around. It is still her - just not with the her memory - but we still have our memories of her.
Didn't mean to go on so long but wanted to give my 2 cents I guess.