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March 13, 2007 -- Want a sharper memory? Lace up your sneakers. Exercise may boost memory, and a new study shows how.
The researchers found that exercise boosts blood flow to a brain area involved in memory -- even in people who aren't in top shape.
Three months of exercise was all it took for people with low levels of aerobic fitness to increase blood flow to that part of their brain and improve their scores on memory tests, the study shows.
Additional tests on mice show new brain cells growing in the same memory-related brain area after two weeks of exercise.
Add it all up, and you've got a good reason to get moving, says researcher Scott Small, MD, of Columbia University in New York.
"I, like many physicians, already encourage my patients to get active and this adds yet another reason to the long list of reasons why exercise is good for overall health," Small says in a Columbia news release.
The new study appears in the early online edition of Proceedings of the National Academy of Sciences.
First, Small's team put running wheels in the cages of 23 mice. For comparison, another 23 mice had no access to running wheels.
As expected, the mice with the running wheels in their cages took full advantage of their exercise gear. They ran on the wheels without any training or encouragement.
Two weeks later, the scientists gave the mice a dye shot to mark new brain cells in the memory-related brain area. After four more weeks, the scientists checked the mice's brains.
The exercising mice had more evidence of new brain cells and more blood flow in the memory-related brain area. The mice with no running wheels in their cages had no new brain cells and no increased blood flow in that brain area.
Next, the researchers focused on people. They recruited 11 healthy volunteers aged 21-45 (average age: 33) with below-average levels of aerobic fitness.
First, participants completed memory tests and an aerobic fitness test. They also got brain scans using magnetic resonance imaging (MRI).
Next, participants shed their sedentary ways. The researchers assigned them to work out for an hour, four times weekly for three months, at Columbia University's fitness center.
The workout routine: Warm up for five minutes at a low intensity on a stationary bike or treadmill, stretch for five minutes, do 40 minutes of aerobic training (on a stationary bike, treadmill, stair machine, or elliptical trainer), and cool down and stretch for 10 minutes.
After three months of exercise, participants repeated the memory tests, aerobic fitness tests, and MRI brain scan.
Those follow-up tests showed an increase in blood flow to the memory-related brain area, better scores on the memory tests, and improvements in aerobic fitness.
The researchers didn't use a dye test to check for new brain cells in the exercisers' brains. So the study doesn't prove that exercise boosted human brain cell production, though exercise apparently had that effect on mice.
The next step is to figure out what exercise regimen is most beneficial for memory, Small notes. He suggests that doctors may one day be able to prescribe specific types of exercise to improve memory.
Meanwhile, be sure to check in with your doctor before starting a new exercise program, especially if you've been physically inactive for a while.