The roles of irisin in improving cognitive, memory and learning function in Alzheimer’s disease (AD) have already been described in previous studies, and elevation of circulating irisin levels by peripheral delivery could pass through the blood–brain barrier and result in enrichment of central irisin which ameliorated both the cognitive deficit and neuropathology in AD mouse models23,24. The gene discussed is FNDC5; the disease is early-onset autosomal dominant Alzheimer disease.