The documentary "Under our Skin" details Alan MacDonald's breakthrough research on how Lyme disease causes Alzheimers. The 4 minute trailer is worth a watch[1], but basically Lyme disease is found in 7 or 10 brains of Alzheimers patients (small sample set). The Lyme disease spirochete literally drills countless pathways in the brain and that causes slow dementia. That spirochete also creates a biofilm which makes it…
I've never heard of this before. Some cursory googling only turns up a sole author publication by Alan MacDonald in Medical Hypotheses and a few news pieces by dodgy organizations like the Spirochaetal Alzheimer's Assocation.
Despite what a lot of people learn in undergrad psych classes, the evidence linking amyloid beta and tau to AD is quite good and getting stronger with every new molecular paper that comes out.
BTW, there doesn't seem to be a correlation between Lyme disease incidence and AD https://www.ncbi.nlm.nih.gov/pubmed/24840565