Bad news. He seems pretty upbeat though, and that bodes well.
Well, this sucks on a level far beyond anything I've seen lately. How awful.
But at least he's aware of it early. Having a head start on something like that has got to count for something.
Because of my major in pscyhology and my interest in neuroscience, I subscribe to a few journals that occasionally report research in alzheimer's. There was recently a very promising breakthrough involving insulin. (Some feel Alzheimer's will eventually be classified as Type 3 Diabetes.) I believe they were able to cure a few mice. If I can locate the article, I'll link you to it if you want.

Anyway, guess my point is I think there's hope for him. I'm keeping my fingers crossed.
So far it hasn't affected his completely amazing sense of humour. That bodes well.