There's a new study where mice who were fed junk food developed the brain tangles characteristic of Alzheimer's. This would explain why my father got Alzheimer's and nobody else in our family has. The Evil Stepmother couldn't really cook, so they had fast food three times a day. Even after his heart attack, when the dietician said they should have more salads, she bought potato and macaroni salads.
If anybody wants to keep up on Alzheimer's articles, the Match It For Pratchett site runs an accumulator at the bottom right.