Some years ago I did some research on prions as part of my interest in mad cow disease. What I found was very disturbing, as well as the possible overlap between diseases like mad cow and Alzheimers.
Now, other doctors are considering the possibility that we could be passing material from one person to another and infecting them with early Alzheimers. It’s very preliminary, but it’s based on the idea that patients with Creutzfeldt-Jakob disease (the human version of mad cow) who received spinal column material had early onset Alzheimers develop while other patients who didn’t receive the material did not.
The biggest issue is that prions, the material that may have been passed, are resistant to normal sterilization procedures. Until we have larger studies on early onset Alzheimers, we won’t know if the issue is widespread or limited to people who already have a prion disease.