MAPT and Alzheimer disease: Cornel iridoid glycoside (CIG) was found in the literature to significantly inhibit abnormal hyperphosphorylation of tau protein, protect the structure of neuronal microtubules, reduce the formation of neurofibrillary tangles, and increase the number of surviving neurons in the cerebral cortex and hippocampus and was shown to remarkably improve the learning and memory function in AD animal models [14].