FNDC5 and Alzheimer disease: It could be of great interest to investigate the role of irisin on cells involved in neuroinflammation, since according to the papers we have discussed below, irisin seems to have a role in attenuating the development and progression of some neurodegenerative diseases, such as Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS).