Proof exercise could protect us from the ravages of Alzheimer’s

A HORMONE released during exercise may protect the brain against Alzheimer's disease, research suggested yesterday.

Irisin is generated by muscle tissue and carried around the body in the bloodstream.

The new evidence indicates it may be behind the known positive effects of exercise on mental performance.

US and Brazilian scientists found lower levels of irisin in the brains of Alzheimer's patients than in healthy individuals. The same was true for the protein from which irisin is derived, FNDC5.

In tests on genetically engineered mice, the scientists induced learning and memory deficits by cutting out irisin. They were able to reverse these effects by restoring the hormone.

When irisin function was blocked in mice with a rodent version of Alzheimer's, the brain benefits of physical exercise were lost.

The research, led by Dr Fernana de Felice from the Federal University of Rio de Janeiro, is reported in the journal Nature Medicine.

Boosting irisin, either with drugs or through exercise, could provide a “novel strategy” for preventing cognitive decline in patients with Alzheimer’s, the scientists said.

British charities welcomed the study. Dr James Pickett, of Alzheimer’s Society, said: “Although this study was only in mice, it adds to mounting evidence of the relationship between lifestyle factors, like physical fitness and dementia.”

Dr Rosa Sancho, from Alzheimer’s Research UK, said: “These interesting findings present a new avenue for future research that could help us better understand how exercise programmes could be targeted to provide the greatest benefit to brain health.

“There are many people either with dementia or at high risk of dementia who have health conditions that make regular exercise more difficult.

“Drugs designed to target the hormone identified in this research could potentially bring some of the benefits of physical activity to people less able to exercise.”