Melatonin, an anti-aging agent, as reported by us and others, supports the normal CNS function in HD through decreasing mutant huntingtin-mediated toxicity [37], and in AD through decreasing Aβ plaques, Tau protein hyperphosphorylation, supporting mitochondrial function and reducing oxidative stress and the inflammatory responses [38-41]. The gene discussed is MAPT; the disease is Alzheimer disease.