Exercise may help keep the brain young by halting the natural decline of new neurons produced in the brain, according to a new study published in the Journal of Applied Physiology.

Researchers at the National Cheng Kung University Medical College in Tainan had mice of four age-groups — young, adult, middle-aged, and elderly — exercise by running on a treadmill for an hour a day.

Compared to those who did not exercise, middle-aged mice who ran had twice the production of neural stem cells in the hippocampus, a region of the brain that is critical in learning and memory formation in many species. An equally exciting finding, new neurons being formed in the brain had much better survival odds than those in the brains of sedentary mice.

What accounts for these changes? Head researcher Yu-Min Kuo explains that "[c]hronic moderate running enhances the production of neurotrophic factor, which promotes neurogenesis, and the differentiation and survival of newborn neurons." In other words, the investigators found that exercise increased the levels of a particular neuronal growth factor, TrkB, as well as TrkB receptors in the hippocampus. Growth factors aid in the development and survival of newly born cells — so the fact that both TrkB receptors and TrkB itself increased makes for an even more robust effect on the survival of the newly hatched nerve cells.

The researchers also found that the effect was more pronounced in the brains of the younger group of mice than it was in older mice. Kuo notes that, just as is true for the many if the other benefits of exercise, "the younger one starts to run, the better."

Based on the similarities between the brains of mice and humans it is likely that the study's results may also hold true for human brains, although more research is needed to support that idea. In the meantime, it certainly can't hurt to add a little exercise to our lives, if at all possible.