Brain HealthHow Exercise Protects the Aging Brain Through the Irisin-BDNF Molecular Axis
When you exercise, your muscles release a hormone called irisin, which travels to the brain and triggers production of BDNF — a key protein that keeps neurons healthy and connected. This review traces the complete molecular pathway behind this muscle-brain conversation, showing how irisin crosses the blood-brain barrier, activates BDNF signaling, and directly counters the hallmarks of Alzheimer's disease: amyloid plaques, tau tangles, neuroinflammation, and poor synaptic plasticity. Crucially, the authors also identify a vicious cycle: Alzheimer's-related oxidative stress and mitochondrial dysfunction suppress this protective axis, accelerating cognitive decline. The review proposes three intervention points — exercise itself, barrier-crossing peptides that boost irisin delivery, and small-molecule drugs that activate the BDNF receptor TrkB — offering a translational roadmap for early Alzheimer's prevention and drug development.
