Here is an interesting take on the announcement. It really gets interesting at #8 in the comments. Apparently, the initial drug, a vaccine, supports other recent studies that indicate beta amyloid (the AD prion) may not be the culprit and may in fact be beneficial. The researcher comments here hint that the mystery compound is an immuno..modulator that functions as a nitrite scavenger.

Good News! Our Alzheimer's Drug didn't Work.

I have run across articles on nitrites in PD. Here is a really interesting one from 2009. It is remarkable to note that the researchers find that increase in death rate from PD and AD was not age related but rather reflective of exposure to food additive nitrosamines that are used as preservatives. I have always felt strongly that our diets play a strong role in etiology, but it really seems understudied.

Nitrates May Be Environmental Trigger For Alzheimer’s, Diabetes And Parkinson's Disease.