HDAC9 and Alzheimer disease: NST is an interesting biotechnological paradigm of MT bioproduct, with clear anti-Aβ, anti-neuroinflammatory, antioxidant, neurotrophic, and epigenetic effects, where its powerful epigenetic effect as a DNA methylating agent, HDAC inhibitor, and sirtuin modulator justifies its regulatory capacity of AD gene expression [199,208,209]; however, the characterization of similar products and their testing in humans is complicated, saving the differences that exist in a transgenic model compared to the neuropathological reality of AD in humans.