In the AD brain, after the tau protein is over phosphorylated by GSK-3β, CDK5, and other phosphorylated kinases, p-tau protein has 10% of the normal tau protein’s binding force when it binds to microtubule protein, and tau protein is detached from microtubules (Phiel et al., 2003); it also misses its biological role of retaining microtubule stability and boosting microtubule formation (Pan et al., 2018). This evidence concerns the gene MAPT and Alzheimer disease.