MAPT and Alzheimer disease: In recent decades, many studies have shown that microRNAs are implicated in the pathogenesis of AD (described in sections “MicroRNAs Involved in the Aβ Hypothesis” and “MicroRNAs Involved in the Tau Phosphorylated Imbalance” and summarized in Tables 1, 2), and alterations of microRNAs were found in serum, plasma and CSF, meaning that microRNAs are exceptional candidates for AD biomarkers.