Power Foods for the Brain (14 page)

By the way, Ben Pridmore is not the champion in all aspects
of memory. There is actually someone who can beat Ben. In Kyoto, Japan, researchers developed a computerized short-term memory test where Ben was resoundingly beaten. The computer program consisted of numbers that flashed momentarily in various places on a screen and were then suddenly replaced by blank squares.
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,
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The subject’s task was to touch each square in what had been the correct numerical order. One, two, three, four, and so on.

Ben sidled up to the computer and did his very best. He was, in fact, very good. But Ben was resoundingly beaten by the local hero, Ayumu. And Ayumu was exactly seven years old at the time. His accuracy was far beyond anything Ben could approach.

Ayumu is a chimpanzee. In the laboratory of Dr. Tetsuro Matsuzawa, Ayumu competes against college students and anyone else who dares try. What Dr. Matsuzawa knows—and now all neuroscientists know—is that chimpanzees are much better than humans at memory tests like this, and no one beats Ayumu. It turns out that just as dogs detect smells and sounds that are out of humans’ sensitivity range and starlings coordinate their flights millisecond by millisecond, chimpanzees have their own set of neuropsychological strengths that make us look like beginners.

If you’d like to try to beat Ayumu’s average, Lumos Labs has prepared an online version of the test he is so good at. You’ll see it at
http://games.lumosity.com/chimp.html
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Of course, Ayumu has had a lot of practice, and figuring out what the humans around him are doing and saying has helped him build up a heck of a lot of cognitive reserve. Not to mention his diet. All those fruits and vegetables, with no meat, dairy products, or fatty foods, keep him fit, too.

E
xercise is good for so many things, and brain health is one of them. As your heart starts pumping, you can just imagine the blood and oxygen surging to your brain, cleaning out the cobwebs and rejuvenating your brain cells. And it’s true. People who exercise regularly have physical differences in their brains that can be seen on special brain scans. The hippocampus—the brain structure that is key for memory—is enhanced by any sort of exercise that gets your heart going. That appears to be true regardless of your age. And as the years go by, people who exercise are much less likely to develop Alzheimer’s disease or have a stroke compared with their coach potato friends. Much as we might like to slip into a life of lazy leisure, the impressive power of exercise is going to lure us into breaking a sweat.

If you’re not convinced, let me describe what science has shown:

Researchers at Columbia University invited a group of young
(twenty-one to forty-five years of age), out-of-shape volunteers to start an exercise program.
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Everyone got his or her choice of a treadmill, bicycle, StairMaster, or elliptical trainer and was asked to exercise for forty minutes, four times a week for twelve weeks. The researchers then scanned their brains using magnetic resonance imaging (MRI). The scans indicated that their brains were actually building new blood vessels and new brain cells—not just anywhere but specifically in the hippocampus. The more physically fit the participants became, the more brain changes they had, and the stronger they performed on cognitive tests.

“But I’m not twenty-one years old!” you might be saying. Well, it looks like exercise works the same way—or even better—for older people. In fact,
it may actually reverse the gradual age-related shrinking of your brain.

Researchers at the University of Illinois recruited fifty-nine adults—all were over age sixty and sedentary—for an exercise program.
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Three times each week, the research volunteers got together for
aerobic
exercise, that is, activities designed to boost the heart rate (e.g., running, step exercises), as opposed to weight-lifting or stretching exercises that don’t quicken your pulse.

After six months, the researchers measured the size of everyone’s brains. Using MRI, they measured their gray matter—that is, the part of the brain made up mostly of brain cells (think of it as the business part of the brain). They also measured their white matter, which is made up mostly of
axons—
long wirelike processes extending from one brain cell to another. White matter is the collection of fibers that keep various parts of the brain and nervous system in communication with each other.

They then compared the results to MRIs done before the exercise program began. It turned out that after six months,
the exercisers’ gray matter was larger than before, especially in the frontal lobe areas essential for memory and attention. Their white matter was larger, too. The part of the white matter that had increased in size was the part of the brain that allows the right and left halves to communicate.

In a later study, researchers zeroed in on the
anterior hippocampus,
which typically shrinks about 1 to 2 percent per year as we age.
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The researchers asked 120 older adults to start a simple walking program and tracked the size of the hippocampus in each person as the study went along.

Three times per week, the participants went for a walk. For the first week, the walks were just ten minutes long but were designed to be brisk enough that the participants’ pulses noticeably increased. They then lengthened the walking sessions by five minutes each week, until they reached forty minutes in length. They then kept up the forty-minute walks and included five minutes of stretching before and after each walk.

MRI scans showed that, yes, exercise
reversed
the gradual brain shrinking that comes with age. That is, it increased the size of the anterior hippocampus. And, in the process, their memory performance improved, too.
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So does this mean that exercise might actually protect us against memory problems as we get older? In a word, yes. Researchers in Seattle’s Group Health Cooperative found that among adults over age sixty-five, those who exercised three times a week were about 40 percent less likely to develop any sort of dementia compared with their not-so-active friends.
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A five-year study in New York found much the same. People who exercised and followed a healthy diet cut their Alzheimer’s risk by as much as 60 percent.
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Swedish researchers did the same kind of study—observing what happens to people as the years go by—and found that
more physically active people were 60 percent less likely to develop Alzheimer’s.
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And
the benefit was especially noticeable among those with the APOE e4 gene,
suggesting once again that choices we make can override our genetic risks.

Several different research teams have estimated the benefit of exercise for preventing dementia, and although the benefits varied from one study to another, overall they show that regular aerobic exercise trims the risk of dementia by about 30 percent and cuts the risk of Alzheimer’s disease roughly in half.
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Okay, so it works. But how? It is easy to see how running, biking, or tennis could strengthen your heart. But what exactly does exercise do to your brain? Well, for starters, exercise works in combination with a healthful diet to keep your arteries clear and open, maintaining a good blood supply. That means oxygen and nutrients go in and wastes come out. Exercise also helps you tackle blood pressure, diabetes, and weight problems, all of which affect the brain.

And part of the credit may go to a substance called BDNF, or
brain-derived neurotrophic factor
, which helps the brain grow new connections (synapses) between brain cells and protects the cells and connections you already have. Aerobic exercise increases the amount of BDNF in your brain.
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That is important, because BDNF tends to be lower in people with Alzheimer’s disease.

As your heart gets pumping, your brain starts laying down new connections between cells, and that seems to be true even for people with the APOE e4 gene.
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Some researchers have also speculated that exercise helps your brain clear out toxins that could lead to the loss of brain cells.
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Think of what this means. Most people lose a bit of ground year by year. The connections from one cell to another start to fall away, and their brains shrink ever so slightly. As time goes on, they feel noticeably less sharp. But when you plug in the effect of regular heart-pumping exercise, everything starts to change. It is a bit like opening the garage door on your long-neglected Ferrari. You’re dusting off your brain, blowing out the exhaust, and taking it out for a spin.

Your brain cells really are rejuvenated, and the results are clear on brain scans, in formal tests, and in how you feel from day to day.

As I mentioned above, exercise is beneficial regardless of age. Even in preadolescence, children who are most physically fit do best on tests of cognitive function.
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So whether you’re twelve, forty-two, sixty-two, or ninety-two, exercises that get your pulse going are good for your brain.

If the idea of beginning a new exercise program sounds a little daunting, let me reassure you. The program I am about to describe is easy. You’ll go at your own pace. Before jumping in, let me mention a few important caveats:

Exercise along with a diet change, not instead of it.
A bad diet can easily undo all the benefits of exercise. So be sure to follow the healthy diet steps described in the previous chapters. Give your Ferrari the fuel it needs.

The value of combining exercise with healthy eating applies not only to brain health but to physical health, as well. When
people try to lose weight with exercise alone—without making any changes to what they are eating—they soon become disappointed.
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,
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To exercise away the calories in a six-piece order of chicken nuggets, you would have to run three miles. If you had a soda with it, that’s another two and a half miles. If you had a burger at your next meal, that means three more miles. In theory, you could exercise all those calories away, but you would not have much time for anything else.

So let exercise add to the benefits of a healthy eating plan rather than take the place of it. As your healthy diet brings down your cholesterol level and helps you steer clear of toxic metals and other undesirables, your exercise regimen will enhance your benefits.

See your doctor.
If you are over forty, have any health problems, or are significantly overweight, see your doctor before you start a new exercise program to make sure you are up to it. Your doctor can check your heart, joints, eyes, and feet.

He or she will also look over whatever medicines you may be taking. Some medicines will limit your ability to do aerobic exercise. For example, if you are on certain blood pressure medicines, your heartbeat will not respond as readily to exercise. So you’ll want to be more cautious.

If you have diabetes, I have some special advice. If you have type 1 diabetes, your blood sugar can drop surprisingly quickly as you exercise. Ditto for people with type 2 diabetes who are taking medications, especially insulin or drugs that stimulate insulin secretion, such as glipizide, glyburide, glimepiride, nateglinide, or repaglinide. Sometimes the low blood sugar arrives quickly; other times it can be delayed for several hours. So you’ll want to be ready for it. Carry a blood glucose monitor and glucose tablets for emergencies, and work with your health-care
provider to adjust your eating schedule and medications if necessary.

Stay safe.
There’s a lot to be said for exercising with a partner, wearing good shoes, wrist protectors, and highly visible clothing, and staying away from traffic.

Start slowly.
If you’ve been sedentary for some time, your body is not ready for a marathon. The arteries to your heart may have been narrowed by a not-so-healthy diet. Your joints are not ready for huge stresses either, and the last thing you want to do is to overwork your body. So take it easy at first. With time, you’ll be able to do more and more. If you were to start a new swimming program, you wouldn’t begin by crossing the English Channel. Any kind of aerobic exercise program should start well within your comfort zone.

Enough theory. It’s time to get started. The program I am about to describe is based on walking. But rather than focusing on distance, we’re going to focus on your pulse. The idea is to gently increase your pulse, boosting blood flow to the brain, for a prescribed period of time. And focusing on your pulse makes it really easy. You can walk and rest as much as you want to. There’s never any need to be overly tired.

We’ll begin by finding your zone—the pulse rate where you’re getting benefits for your brain and body but are still within the bounds of safety. Then we’ll gently pump up your pulse, getting the blood flowing to your brain. We’ll gradually pick things up, letting you control the pace every step of the way. Finally, we’ll take steps to keep you in the groove so that your exercise investment pays off maximally.

Find your target zone.
As you exercise, you’ll want to get your heart beating fast enough so that you benefit physically but not so fast that you strain your heart. To find the safety zone for your pulse rate, your doctor could give you a stress test. This is usually done by walking on a treadmill with wires from an electrocardiogram attached to your chest. The goal is to see how much you can exert yourself without signs of stress to the heart, such as chest pain or EKG changes.

A simpler way to calculate your safety zone is based on your age. First, subtract your age from 220. So, for example, if you are 60 years old, 220 minus 60 is 160. What you have just calculated is the absolute maximum pulse your heart could take. Now, for safety, you should stay well under that number.