NEUROD1 and Alzheimer disease: Although previous research demonstrated that iPSCs grafted to AD mouse model reduced plaque deposition and improved cognitive dysfunction (Cha et al., 2017), and that reactive glial cells in the cortex of AD model mice can be directly reprogrammed into functional neurons in vivo using retroviral expression of a single neural transcription factor, NeuroD1 (Guo et al., 2014), only a few studies have reported in vivo reprogramming in AD animal models.