Rody et al. also emphasized recently the neuroprotective function of irisin, a myokine derived from the proteolytic cleavage of the fibronectin type III domain-containing protein 5 (FNDC5) transmembrane protein, showing the evidence that physical exercise may serve as a preventive and therapeutic approach to cognitive decline in Alzheimer’s disease [214]. Here, FNDC5 is linked to early-onset autosomal dominant Alzheimer disease.