A hormone released during exercise may protect the brain against Alzheimer’s disease. It may also explain the known positive effects of exercise on mental performance.
Irisin is a hormone generated by muscle tissue that is carried around the body in the bloodstream. Fernana de Felice at the Federal University of Rio de Janerio and colleagues found that people with Alzheimer’s had lower levels of the hormone compared with healthy individuals.In tests with mice, the team could induce learning and memory deficits by cutting out irisin and could reverse the effects by restoring the hormone. When irisin signalling was blocked in mice with a rodent version of Alzheimer’s, the brain benefits of physical exercise were lost.
“We know that physical activity is linked to better brain health as we age, and this research highlights a biological mechanism that may contribute to this beneficial effect,” says Rosa Sancho at the charity Alzheimer’s Research UK.