Is Alzheimer's disease hereditary?

Unfortunately my Grandad has Alzheimer's disease, and is living in a home at the moment with my Grandma, who is looking the same way as him.
He has deteriorated gradually over the past 7 years, and is just starting to lose his health now. I am finding it really hard to come to terms with, as the doctors have no answers for us, and we are now just playing a horrid waiting game :'(
I am really worried about my Dad though. He is a little forgetful, and always has been, but I have this sickening feeling that he may eventually follow the same fate. Is there any way that he can keep "with it" at all? My friend suggested buying him Brain Training on DS, and doing Sudoku and crosswords to keep his mind stimulated. Will this make a difference? And is there any way to check if he will be affected by the disease?
Also, is there anyway that I could get it in the future? I am only 16, but would it be possible? Thank you, and if you are going to be nasty, please don't even bother answering because this is not a subject that should be joked about. Much appreciated :)

It is hereditary, but you can prolong it if you keep your mind extremely active, especially after the age of 40.

It's possible in some families. You'd be lucky if it isn't hereditary in your family. Because Alzheimer's disease is horrible and very sad. It's aweful seeing family members get torn down from it. Well, it depends.

if it is i'm screwed. my mother had alzheimer's and my father had dementia. i do cross word puzzles too. i'm going to ask my doctor is there is anything to prevent it.

according to my book, it is hereditary.. so, while your still young try to prevent it... it's really an effect of aging but you can delay it...

Alzheimers is not a hereditary disease, it is a form of dementia,which obviously anyone can get, i agree with your friend, it is recommended to keep your brain stimulated by doing a crossword puzzle daily,don't worry about your dad, as we get older we do sometimes forget things, but as your nan and grandad are both suffering from dementia you are probably worrying too much about your dad and noticing silly little things that you wouldn't normally, i am sure he will be fine,i am a carer and look after lots of people with these problems,and have never known their relatives to inherit this disease,

My grandmother just recently passed away at 89. She had Alzheimer's disease for about 10 years. It just got worse and worse over time. Yes you can try to stimulate there brain but eventually it will stop working. Before she passed away she forgot how to swallow, how to go to the bathroom, and forgot how to talk. Overtime her whole body just shut down. There is a medicine called accept that slows the progression of the disease. Also many of them can be a little violent to the people closes to them. Good Luck and you will be in my prayers, I know its scary but hang in there.