MAPT and Alzheimer disease: The pathogenesis of AD is very complex and involves β-amyloid protein metabolism disorder and deposition, neurofibrillary tangle (NFT) formation due to abnormal or excessive tau phosphorylation, cholinergic neuron damage, neuroinflammation, abnormal epigenetic modification, intestinal microbiota dysbiosis, abnormal glucose and lipid metabolism, and oxidative stress [3].