Recent research suggests that our brains attack bacteria with amyloid beta. The result of a low-level bacterial infection is therefore not a lot of bacteria, b

Recent research suggests that our brains attack bacteria with amyloid beta. The result of a low-level bacterial infection is therefore not a lot of bacteria, but ever growing amounts of amyloid beta plaques. Which are easy to spot. After that, it is a question of what kinds of bacteria attack brains. Until recently, the prevailing theory was that the amyloid beta plaques were themselves the cause of Alzheimers. As a result we spent an insane amount of money developing a variety of drugs that would clear/prevent those plaques. They did reduce the plaques, but did absolutely nothing for the disease. However with virtually all research money devoted to this theory, and all top researchers on record as believing it, alternative theories fought an uphill battle for acceptance. The old theory is still conventional wisdom and a lot of research efforts are focused on it. But there is mounting evidence for the infectious model. The result is a classic paradigm shift in Kuhn's sense of the word where researchers in each paradigm literally speak past the other. Each regarding their theory as proven. To someone who thinks that infectious disease is the problem, the fact that mouth bacteria have been found in the brain, plus a correlation between gum disease and Alzheimer's, is a smoking gun for causation. To someone who thinks that amyloid beta is the problem, it is an interesting correlation but not compelling enough to overturn the prevailing theory.