Grandpa has Alzheimer's? Help!?

OK so my Grandpa is about 76 and he forgets things, like what time to wake up, when he has to "go", I'm really worried about him. This Morning my Grandma called and Said that my Grandpa didn't remember, my uncle " his own son"! My mom was devistated, and she has been really angry, she keeps saying " Why did this have to happen to my Dad! I prayed to god that he wouldn't do this to him! My Dad was a great person and had a great life full of great people that loved him , and now he dosent remeber anything! I dont want my dad to die and leave this planet not knowing im his only daughter and i love him!" Hearing this at only 12 i was crying my gutts out! I love my pappy, I then had a flash back of when I was little, maybe at age 3 and i would hug him goodbye and he would say " See you ater alligator" then I said " After While Crocodile", and he used to argue with my grandma, and he used to build things in this woodshop, Now when I look at him he staresat me like he knows me. but forgot my name. I see him every sunday, and a few days ago he was over here at my house, and I lifted up a picture of my mom with a band, and asked " Do you know anyone in this picture pappy? And he pointed to a drummer! My heart was broken! Please! Is there anythng I can do!? I dont want him to forget me! What if im next! He goes to this daycare thing on Wedsdays and talks to people and has a great time, but i'm scared! Do you have any stories about your friends or family that have Alzheimers? I want him back!