Preclinical studies using animal models of AD with the depleted gut microbiota, derived by crossing with germ‐free mice (genetically and environmentally devoid of microorganisms) or by using either long‐term broad‐spectrum combinatorial antibiotic treatment, have demonstrated that the lack of gut microbiota induces a reduction of Aβ pathology, a delay in memory‐deficits, and an altered microglial activation status, which occurs in concert with a reduction in tau accumulation (Harach et al., 2017; Mezö et al., 2020; Minter et al., 2016; Seo et al., 2023). Here, MAPT is linked to Alzheimer disease.