Another reason to follow through with that New Year's resolution: Aerobic exercise keeps the aging brain -- as well as the aging body -- in fighting form. Researchers at the University of Pittsburgh, the University of Illinois, Rice University and Ohio State showed that a program of aerobic exercise, over the course of a year, can increase the size of the hippocampus -- a part of the brain key to memory and spatial navigation -- in adults ages 55 to 80.
The hippocampus is known to shrink in late adulthood, leading to memory impairment.
The results were made public Monday by the journal Proceedings of the National Academy of Sciences. They back up earlier research that has shown a correlation between fitness level and brain function.
To complete the study, the team recruited 120 older people who didn't exercise regularly. Half were randomly assigned to an aerobic exercise program, walking around a track three days a week for 40 minutes per session. The other half embarked on a stretching-and-weights program. Both groups were carefully coached and monitored. They provided blood samples, performed spatial memory exercises and were given MRIs at the beginning, halfway point and end of the research period.
The group doing aerobic exercise had increases in hippocampus volume: up 2.12 % in the left hippocampus, and 1.97% in the right hippocampus. The stretching group, on the other hand, had decreased hippocampus volume: down 1.40% on the left and 1.43% on the right.
The participants also performed spatial memory exercises. Again, the aerobic exercise group had better function by the end of the year of exercise. Blood tests also showed an increase in the levels of brain-derived neurotrophic factor, a chemical involved with learning and memory, among the walkers. Increases in hippocampal size were associated with increased amounts of brain-derived neurotrophic factor.
"We demonstrate that loss of hippocampal volume in late adulthood is not inevitable and can be reversed with moderate-intensity exercise," the team wrote, suggesting that a few laps around the track might be a particularly cost-effective way to treat a widespread health problem -- without the side effects of medication.
And, researchers said, it's never too late. "Starting an exercise regimen later in life is not futile for either enhancing cognition or augmenting brain volume," the team wrote.