Exercise could play a bigger role in preventing cognitive decline than previously thought. That is one finding of research from the University of Missouri, offering fresh insights into brain health. The study, published in The Journal of Physiology, explains that when the body runs low on its usual fuel for various organs, the liver steps up an alternative energy source that helps the brain with memory, learning and overall health. But what if the liver can’t deliver enough alternative ketone fuel? As expected--a noticeable decline in brain function. But then, the researchers discovered something remarkable happened. Exercise managed to reverse that cognitive decline. Authors say exercise could be the best piece of the puzzle in preserving brain health as we age.