Moreover, as shown in the study by Lu et al., the overexpression of circHDAC9 remarkably decreases the miR-138 level and increases the level of the Sirt1 protein to subsequently significantly rescue the miR-138-induced inhibition of ADAM10 and increase in Aβ levels, indicating its potential as a novel early diagnostic marker and therapeutic target for AD. Here, SIRT1 is linked to Alzheimer disease.