Similar to models of AD, in both in vitro and in vivo models of HD SIRT1 expression and activity can activate multiple targets and transcriptional pathways that regulate processes such as mitochondrial biogenesis, antioxidant defense, and neurotrophic support, thereby providing a protective effect against mutant Huntingtin (mut-Htt) [9, 21, 22]. The gene discussed is SIRT1; the disease is Alzheimer disease.