In a study published on Jan. 31 in The Proceedings of the National Academy of Sciences, researchers randomly assigned 120 healthy but sedentary men and women (average age mid-60s) to one of two exercise groups. One group walked around a track three times a week, building up to 40 minutes at a stretch; the other did a variety of less aerobic exercises, including yoga and resistance training with bands.
After a year, brain scans showed that among the walkers, the hippocampus had increased in volume by about 2 percent on average; in the others, it had declined by about 1.4 percent. Since such a decline is normal in older adults, “a 2 percent increase is fairly significant,” said the lead author, Kirk Erickson, a psychologist at the University of Pittsburgh. Both groups also improved on a test of spatial memory, but the walkers improved more.