Actually, a pretty good Op-ed on "preventing Alzheimer's"

CNN has a piece about what we can all do to reduce the pace and severity of cognitive decline.  Unlike most articles one finds on the web that claim some preventative measure for Alzheimer's, but are really just touting some supplement with little to no evidence of any real benefit, this article offers some pretty good advice.  Though you may be surprised at what that advice is.  It is not a supplement or anything so simple as a pill or new antioxidant filled fruit because the bottom line is that Alzheimer's disease is a complex disease that results from several genetic and environmental factors, many of which still remain unknown.  So what can you possibly do to combat such a complex disease: keep your heart healthy.  That's right.  I have written before that the number one thing you can do for your brain is exercise regularly (healthy body, healthy mind), and most of the other advice in the article follows along these lines: don't smoke, try to keep stress and blood pressure low (i.e. positive attitude and lots of friends and social networks), and try to eat a diet that will keep your circulatory system healthy (again keeping blood pressure and LDL cholesterol low).  I know it's not nearly as appealing as taking a pill every morning, but if you have a history of Alzheimer's or dementia in your family, you may want to consider taking a morning jog instead and a good hard look at what you eat.  (And get some of your friends and family to join you.)