Animal experiments have shown that compared with wildtype mice, APP/PS1 mice begin to show alterations in the intestinal microbiota after 3 months of age, which become more pronounced after 6 months, with a high enrichment of intestinal microbiota associated with inflammation preceding the appearance of key pathological AD features such as brain Aβ deposition and microglial activation [56,57]. The gene discussed is APP; the disease is Alzheimer disease.