There's a very small structure deep in the center of our brains called the hippocampus. It's smaller than your pinkie, but it plays an absolutely essential role in learning and memory. The hippocampus encodes new information so that we can recall it later. Without a hippocampus, we would be unable to form new memories; we'd only be able to remember the old ones.
As part of normal aging, the hippocampus shrinks. And this shrinkage speeds up as we grow older, foreshadowing memory problems and dementias like Alzheimer's disease.
But there's been some good news in the past decade: Scientists have discovered that in certain areas of the aging brain, new cells are born and grow throughout through life. Neuroscientist Peter Snyder, a researcher at Brown University's Alpert Medical School and Rhode Island Hospital, says the hippocampus is one of those brain areas that continue to form new cells and make new connections between cells.
"What we're finding is that of all of these noninvasive ways of intervening, it is exercise that seems to have the most efficacy at this point — more so than nutritional supplements, vitamins and cognitive interventions," says Snyder, who studies what we can do to maintain memory as our brains age.
