That's probably because both Alzheimers and AI/AF are symptoms of mercury (Hg) toxicity.
You can read about that in the writings of a couple of PhD chemists who are active in heavy metal detox--Andrew Cutler and Boyd Haley.
Haley, the former chair of teh chem dept at the U of KY, has a number of Youtube videos on the subject and a paper or two.
Haley says that a hormone receptor that is related to pituitary hormones ACTH FSH, etc holds onto Hg about as well as anything can. He says people with a number of mercury Amalgam
fillings have roughly the same amount of Hg in the blood as ACTH!
Cutler has largely recovered from his Hg toxicity and had AI/AF. He has quite a few sections on it in his book, Amalgam
Illness Diagnosis and Treatment--noamalgam.com
You might check out the video by the U of Calgary on one effect of Hg on brain cells. Haley explains more in his videos.
more could be said.!