If your objective is mainly to obtain information about Alzheimer's, then this isn't the best book for you, since it's way too long-winded and spends endless time recounting the search for cures that didn't pan out. Bottom line: there is no cure and not much that can be done, other than to help sufferers get as much as possible from what time they have left. Yes, you can do a PET scan to determine whether you have beta-amyloid plaques, but nobody really understands how those relate to Alzheimer's, since some people without the disease still have the plaques.
A hundred pages would have been more than enough to get that message across.
If, on the other hand, you're interested in the history of the disease and the attempts that have been made, the financial issues and the politics involved, then you might find this book more interesting.