There’s growing evidence that exercise is not just good for the body, but also the brain, boosting memory and overall brain health. It’s been proven that active people are less likely to develop Alzheimer’s disease and there is even evidence that exercise can improve the cognitive abilities of people with mild cognitive impairment when combined with a healthy diet and brain training. But now scientists are taking it step further—they’ve uncovered exactly what happens in the brain when we exercise, why it boosts our learning and memory skills, and how this could help develop a new treatment for Alzheimer’s disease.
Exercise stimulates a process called neurogenesis—the creation of new nerve cells—in the hippocampus, the brain’s learning and memory center. It’s essential for the creation of new memories. But in Alzheimer’s disease, it stops working the way it should. Researchers wanted to find out if increasing neurogenesis could improve the cognitive abilities of mice genetically programmed to have Alzheimer’s disease.
They ran two parallel studies on mice engineered to have Alzheimer’s disease. In one, mice were encouraged to exercise by being placed in environments with running wheels for three hours at a time. In the other, they were given a combination of gene therapy and drugs designed to stimulate the production of new nerve cells. When the cognitive abilities of the mice were tested, they found that those on the exercise regimen improved more than those given the combination therapies. The mice in the exercise study also had lower levels of beta-amyloid plaque, one of the toxic proteins associated with Alzheimer’s disease.
Researchers concluded that kickstarting the growth of new cells wasn’t enough—the drugs and gene therapy had successfully produced new nerve cells, but they couldn’t survive in the toxic, inflamed environment of an Alzheimer’s brain. Exercise didn’t just stimulate the growth of new cells, it also turned on the production of a substance called brain-derived neurotrophic factor, or B.D.N.F., that can “clean up” inflammation in the brain, making it easier for the new cells to survive and thrive. When scientists used the drugs and gene therapy, and at the same time upped the production of B.D.N.F., they found they could
“The lesson learned was that it is not enough just to turn on the birth of new nerve cells, you must simultaneously ‘clean up’ the neighborhood in which they are being born to make sure the new cells survive and thrive,” said Rudy Tanzi, one of the lead study authors. “Exercise can achieve that, but we found ways of mimicking those beneficial cognitive effects by the application of drugs and gene therapy that simultaneously turn on neurogenesis and B.D.N.F. production,” he said. The researchers hope to see if they can reproduce the same results in human trials in order to judge whether exercise could be a viable treatment for Alzheimer’s disease or prevention.