This is How Exercise May Protect Against Alzheimer's

The hippocampus, an organ located within the brain's medial temporal lobe, is associated with learning and memory, particularly long-term memory. As such, the scientists posited that it is the effects that exercise-released irisin has on this organ that explain the role of exercise in deterring memory loss.

"This raised the possibility that irisin may help explain why physical activity improves memory and seems to play a protective role in brain disorders such as Alzheimer's disease" said study lead Ottavio Arancio, MD, PhD, and a researcher at Columbia University's Vagelos College of Physicians and Surgeons and Taub Institute for Research on Alzheimer's Disease and the Aging Brain.

Studying irisin's effects

To study their hypothesis, the scientists decided to look at the levels of irisin in Alzheimer's patients. What they found was that they had reduced hippocampal levels of the hormone.

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So, the researchers decided to explore irisin's effects on mice test subjects. Low and behold, it was determined that irisin in mice protected the brain's synapses and memory capabilities.

When irisin was disabled both those areas were weakened. When it was boosted, both improved.

Furthermore, the researchers gave mice infusions of beta amyloid, the protein responsible for robbing Alzheimer's patients of their memory. Impressively, the mice who swam nearly every day did not have any memory loss despite the infusions.

However, when they blocked irisin, swimming had no positive effects whatsoever. 

Arancio and his team are now looking for pharmaceutical compounds that can either increase levels of irisin or mimic its effects in order to treat or prevent dementia. 

"In the meantime, I would certainly encourage everyone to exercise, to promote brain function and overall health," he said. "But that's not possible for many people, especially those with age-related conditions like heart disease, arthritis, or dementia. For those individuals, there's a particular need for drugs that can mimic the effects of irisin and protect synapses and prevent cognitive decline.

The study was published in Nature Medicine.