In a recent study, the tau-protein-mediated neurodegeneration of AD has been linked to the microbiome in mice, showing that when manipulating the microbiome with either antibiotics or germ-free rearing, a strong reduction in inflammation, tau-protein-related neurodegeneration, and brain atrophy in the hippocampus was seen, and the effects were modulated by ApoE, the protein most associated with the development of AD in humans [115]. The gene discussed is APOE; the disease is Alzheimer disease.