Numerous human studies have demonstrated that bacteria, such as Helicobacter pylori, Borrelia burgdorferi, and Chlamydia pneumoniae, increase AD susceptibility by promoting tau protein hyperphosphorylation and elevating proinflammatory bacteria (Escherichia/Shigella) and decreasing anti-inflammatory gut microbiota (Ruminococcus) (Murray, Kemp & Nguyen, 2022; Cryan et al., 2019). This evidence concerns the gene MAPT and Alzheimer disease.