I can start to see my mother showing early signs of dementia. I feel really helpless about it, since it shows how vulnerable they are. I try to help with small things, but it's sad knowing I won't be able to slow down the effects of it.
That's very sad. My Grandma had that and it is devastating to experience it. I'm told that doing puzzles etc. keeps the brain active and maybe at least delays it.
I heard that too! I try to do some of those here and there, but I get kind of tired of them after a while when I'm not successful. I'm really just dreading her getting much worse and not recognizing me, and having it seem like the past never happened. 
I really feel for you. It's not easy, I won't kid you. But at least you understand what's happening and are obviously prepared for the inevitable.