[jjoonathan]

The idea that clumps of proteins misfolded into stacked beta sheets (beta amyloid plaques, i.e. Alzheimer's) tend to cause other proteins to misfold into beta sheets and join the glob. So, exactly like a prion except with a "messier" mechanism that doesn't strictly follow A+B->B+B.

Which raises the question: did prion diseases ever really strictly follow A+B->B+B? Can Alzheimer's be transmitted by eating "infected" brain tissue? If the answers are "No" and "Yes", then it seems that what we mistook for two diseases (because of differing context and symptoms) was actually one underlying mechanism (with different context and symptoms).

Disclaimer: I Am Not An Epidemiologist, I am not extensively familiar with recent literature on the subject, I just did a bit of unrelated work in computational protein folding and couldn't help but wonder.