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Although physical activity is known to improve memory and may reduce the risk of Alzheimer's disease, researchers did not understand why.
According to a study conducted jointly by Dr. Ottavio Arancio, a researcher at the College of Physicians and Surgeons Vagelos of Columbia University, the Institute for Research on Alzheimer's Disease of the University of Columbia, has demonstrated that exercise produces a hormone that can improve memory and protect against Alzheimer's disease. the aging brain.
A few years ago, practicing researchers discovered a hormone called irisine, which is released into the circulation during physical activity. Early studies have suggested that irisine plays primarily a role in energy metabolism. But new research has shown that the hormone can also promote neuronal growth in the brain's hippocampus, a crucial area for learning and memory.
"This suggests the possibility that irisin may help to explain why physical activity improves memory and appears to play a protective role in brain disorders such as Alzheimer's disease," he said. Dr. Arancio.
Irisine reduced in the brains of people with Alzheimer's disease
In this new study, Dr. Arancio and his colleagues from the University of Rio de Janeiro (Brazil) and Queens University (Canada) began by looking for a link between irisin and Alzheimer's disease in men. man. Using tissue samples taken from brain stores, they discovered that irisin was present in the human hippocampus and that hormone levels in the The hippocampus was reduced in people with Alzheimer's disease.
To explore what irisin does in the brain, the team has turned to the mouse. Their experiments show that irisin in mice protects brain synapses and animal memory. When irisin was deactivated in the hippocampus of healthy mice, synapses and memory were weakened. Similarly, increasing levels of irisin in the brain has improved both measures of brain health.
Swimming stimulates irisin
The researchers then examined the effect of exercise on irisin and the brain. As part of the most compelling experiments in the study, researchers found that mice swimming almost daily for five weeks did not exhibit memory impairment despite beta-amyloid infusions – the protein that cumbers neurons and destructive memory involved in Alzheimer's.
By blocking irisin with a drug, the researchers also discovered that the benefits of swimming were totally eliminated. Mice that swam and were treated with irisin-blocking substances did not behave better in memory tests than sedentary animals after beta-amyloid infusions.
Together, the results suggest that irisin could be harnessed to find a new treatment to prevent or treat dementia in humans, says Dr. Arancio. His team is now researching pharmaceutical compounds that can increase brain levels of the hormone or mimic its action.
"In the meantime, I would certainly encourage everyone to exercise to promote brain function and health in general," he said. "But this is not possible for many people, especially those who suffer from age-related diseases such as heart disease, arthritis or dementia. For these people, there is a particular need for drugs that mimic the effects of irisin, protect synapses, and prevent cognitive decline. "
The study titled "FNDC5 / exercise-related irisin rescues synaptic plasticity and memory defects in Alzheimer's models" was published in Nature Medicine.
