Exercise To Keep Your Brain Young

About the time we enter our forties, most of us notice our bodies are slowing down. Running, climbing, and reaching may become more difficult. Our sexual stamina may be diminished. We gain weight more easily and lose it with more difficulty, and chronic diseases may begin to set it.

The usual prescription for avoiding these early signs of aging is to exercise. It turns out, recent studies have found, that physical exercise also helps preserve our mental abilities.

"Middle Aging" of the Brain

As we go into the fifth decade of our lives, the way our brains work begins to change. It's as if the "toggle switch" in our brains doesn't work as well. It is not just harder to multi-task, it's also harder to switch between tasks. We have more difficulties with problem solving, concentration, and certain kinds of decisions. Our knowledge base and life experience, of course, continue to increase, often compensating for these changes, but neurologists now have little doubt that there are changes in the activation of the prefrontal cortex of the brain.

In younger people, activation of the prefrontal cortex during "higher level" intellectual activity tends to be localized. Brain scans show lighting up on just the left side or just the right side of the brain. When neuroscientists look at the brains of people who are over the age of 40 performing mental tasks, however, they often see activation on both sides of the brain. The lessening of "asymmetrical activation" in the brain seems to indicate that more brain power is needed to perform the same tasks. Neuroscientists have even invented an acronym to describe this phenomenon, HAROLD, for hemispheric asymmetry reduction in older adults.

What scientists have not known until recently was whether HAROLD could be reduced or even prevented with lifestyle changes.

Aerobic Fitness and Brain Activation

The possibility of preventing this aspect of brain aging attracted the attention of Dr. Hideaki Soya, a professor of exercise and neuroendocrinology at the University of Tsukuba in Japan. Dr. Soya and his colleagues recruited 60 Japanese men between the ages of 64 and 75 who showed no obvious signs of dementia to participate in a study.

The research team first tested the men's aerobic fitness. Then, on a follow-up visit, they fitted the men with infrared sensors that measure the flow of blood and uptake of oxygen in the brain. The volunteers were given the task of pressing buttons corresponding to a word on the screen, the name of a color, but not the color of the background of the word. For instance, if the test had been conducted in English, "G-R-E-E-N" might appear on a blue background, and the participants would be expected to press the button for green, not blue.

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This task takes considerable brain power, and in younger people has been shown to light up the left side of the prefrontal cortex. When scientists have given this task to older people, they have found that the right side of the brain usually also lights up. In aerobically fit older men, however, just the left prefrontal cortex showed higher blood flow and oxygen uptake, similar to younger volunteers.

How To Keep Your Brain Young

Dr. Soya noted that in terms of attention and rapid decision making, the brains of physically fit older volunteers are like those of younger volunteers. Physically fit elders were faster and more accurate in their responses than older volunteers with lower levels of aerobic fitness, indicating superior attention and reasoning abilities.

This study did not prove that exercise keeps the brain young, only that physically fit men have better brain activity for certain kinds of intellectual tasks. The research team did not investigate specifically which kinds of physical activity helped the older volunteers stay in good mental shape. In general, however, physically fit older people still walk, and perhaps still participate in other activities that keep both body and brain in good condition, such as jogging, sports, and swimming.

Dr. Soya's study is not the only investigation of the role of exercise in maintaining brain health during aging. At least 1073 other studies have looked at aspects of the same issue. Certain recommendations emerge from the scientific literature:

• Regular physical exercise seems to increase angiogenesis, neurogenesis, synaptogenesis, and the synthesis of neurotransmitters, the growth of blood vessels, the creation of new neurons, the construction of new networks in the brain, and the maintenance of healthy levels of chemicals in the brain. The most effective exercise for this purpose combines aerobic activity with coordination activity, for example, hitting a ball, climbing a rock face, running a competitive race. Just repeating the same motions over and over again, such as spending half an hour on ellipticals or working out on an exercise bicycle, doesn't have the same effect.
• Even when people haven't been physically active, "just get moving" exercises help activate the areas of their brains that are needed in more complex sports. A study at the University of Kansas recruited people to work out on ellipticals or treadmills for 75, 150, or 225 minutes a week, in five sessions of 15, 30, or 45 minutes each. As little as 75 minutes of exercise per week increases attention, the ability to concentrate, and the more people exercise, the more their visuospatial ability, their eye-hand coordination improved. If you want to take up a sport or continue a sport in your senior years, then even simple, aerobic exercise can help. Games and sports just help more.

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• It isn't necessary to work out hard to get brain benefits from exercise. In fact, it's not even always a good idea. Mild to moderate physical exercise increases blood flow through the carotid artery to the brain. Intense physical exercise may actually decrease it. It's better to spend 15 minutes to an hour a day doing physical activities you enjoy, at a comfortable pace, than it is to work hard to try to improve your stamina. After age 60, in particular, exercise is more about preserving your abilities than increasing them, although occasionally late bloomers find a new sport even in the seventh and eighth and ninth decades of life.

There's no doubt that "doing something" just a few (15 to 30) minutes four or five times a week helps you stay more "with it" and engaged in the world around you. Mild aerobic exercise may wake up your brain so you can continue or take up more complex physical activities. It doesn't take a lot to help keep your brain in shape, and the benefits far outweigh the investment of your time.