For people who have mutations in some candidate genes, an infectious attack can overwhelm the brain by overproducing beta amyloid. There is so much amyloid that it clumps on its own, without the presence of microbes. This overabundance of amyloid can disrupt normal cell-cell communication. Will everyone who has had a brain infection develop Alzheimer’s? It depends on brain’s ability to clear out b-amyloid after they have killed microbes. People with gene mutations or people with the ApoE4 gene, may not be able to clear the microbes and plaques and therefore have a high risk of Alzheimer’s.
With AD patients representing a huge unmet medical need, and experimental drugs failing in clinical trials, this infectious disease theory definitely needs serious attention. If researchers can prove the theory and sort out the many puzzling details, Alzheimer’s could become a preventable illness.