Irisin is a myokine derived from fibronectin type III domain containing 5 (FNDC5) released into the circulation during physical exercise. It is known that FNDC5/irisin stimulates brain-derived neurotrophic factor (BDNF) expression in the hippocampus and also that Alzheimer’s disease (AD) models and brains and cerebrospinal fluid of AD patients have low levels of irisin.