Brain Rules

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IF THE CAMERAS weren't rolling and the media abuzz with live reports, it is possible nobody would have believed the following story:

A man had been handcuffed, shackled and thrown into California's Long Beach Harbor, where he was quickly fastened to a floating cable. The cable had been attached at the other end to 70 boats, bobbing up and down in the harbor, each carrying a single person. Battling strong winds and currents, the man then swam, towing all 70 boats (and passengers) behind him, traveling 1.5 miles to Queen's Way Bridge. The man, Jack La Lanne, was celebrating his birthday. He had just turned 70 years old.

Jack La Lanne, born in 1914, has been called the godfather of the American fitness movement. He starred in one of the longest-running exercise programs produced for commercial television. A prolific inventor, La Lanne designed the first legextension machines, the first cable-fastened pulleys, and the first weight selectors, all now standard issue in the modern gym. He is even credited with inventing an exercise that supposedly bears his name, the Jumping Jack. La Lanne is now in his mid-90s, and even these feats are probably not the most interesting aspect of this famed bodybuilder's story. If you ever have the chance to hear him in an interview, your biggest impression will be not the strength of his muscles but the strength of his mind. La Lanne is mentally alert, almost beyond reason. His sense of humor is both lightening fast and improvisatory. "I tell people I can't afford to die. It will wreck my image!" he once exclaimed to Larry King. He regularly rails at the camera: "Why am I so strong? Do you know how many calories are in butter and cheese and ice cream? Would you get your dog up in the morning for a cup of coffee and a doughnut?" He claims he hasn't had dessert since 1929. He is hyper-energized, opinionated, possessed with the intellectual vigor of an athlete in his 20s.

So it's hard not to ask: "Is there a relationship between exercise and mental alertness?" The answer, it turns out, is yes.

survival of the fittest

Though a great deal of our evolutionary history remains shrouded in controversy, the one fact that every paleoanthropologist on the planet accepts can be summarized in two words:

We moved.

A lot. When our bountiful rainforests began to shrink, collapsing the local food supply, we were forced to wander around an increasingly dry landscape looking for more trees we could scamper up to dine. As the climate got more arid, these wet botanical vending machines disappeared altogether. Instead of moving up and down complex arboreal environments in three dimensions, which required a lot of dexterity, we began walking back and forth across arid savannahs in two dimensions, which required a lot of stamina.

"About 10 to 20 kilometers a day with men," says famed anthropologist Richard Wrangham, "and about half that for women." That's the amount of ground scientists estimate we covered on a daily basis back then-up to 12 miles a day. That means our fancy brains developed not while we were lounging around but while we were working out.

The first real marathon runner of our species was a vicious predator known as Homo erectus. As soon as the Homo erectus family evolved, about 2 million years ago, he started moving out of town. Our direct ancestors, Homo sapiens, rapidly did the same thing, starting in Africa 100,000 years ago and reaching Argentina by 12,000 years ago. Some researchers suggest that we were extending our ranges by an unheard-of 25 miles per year.

This is an impressive feat, considering the nature of the world our ancestors inhabited. They were crossing rivers and deserts, jungles and mountain ranges, all without the aid of maps and mostly without tools. They eventually made ocean-going boats without the benefit of wheels or metallurgy, and then traveling up and down the Pacific with only the crudest navigational skills. Our ancestors constantly were encountering new food sources, new predators, new physical dangers. Along the road they routinely suffered injuries, experienced strange illnesses, and delivered and nurtured children, all without the benefit of textbooks or modern medicine.

Given our relative wimpiness in the animal kingdom (we don't even have enough body hair to survive a mildly chilly night), what these data tell us is that we grew up in top physical shape, or we didn't grow up at all. And they also tell us the human brain became the most powerful in the world under conditions where motion was a constant presence.

If our unique cognitive skills were forged in the furnace of physical activity, is it possible that physical activity still influences our cognitive skills? Are the cognitive abilities of someone in good physical condition different from those of someone in poor physical condition? And what if someone in poor physical condition were whipped into shape? Those are scientifically testable questions. The answers are directly related to why Jack La Lanne can still crack jokes about eating dessert. In his nineties.

will you age like jim or like frank?

We discovered the beneficial effects of exercise on the brain by looking at aging populations. This was brought home to me by an anonymous man named Jim and a famous man named Frank. I met them both while I was watching television. A documentary on American nursing homes showed people in wheelchairs, many in their mid- to late 80s, lining the halls of a dimly lit facility, just sitting around, seemingly waiting to die. One was named Jim. His eyes seemed vacant, lonely, friendless. He could cry at the drop of a hat but otherwise spent the last years of his life mostly staring off into space. I switched channels. I stumbled upon a very young-looking Mike Wallace. The journalist was busy interviewing architect Frank Lloyd Wright, at the time in his late 80s. I was about to hear a most riveting interview.

"When I walk into St. Patrick's Cathedral ... here in New York City, I am enveloped in a feeling of reverence," said Wallace, tapping his cigarette. The old man eyed Wallace. "Sure it isn't an inferiority complex?"

"Just because the building is big and I'm small, you mean?"

"Yes."

"I think not."

"I hope not."

"You feel nothing when you go into St. Patrick's?"

"Regret," Wright said without a moment's pause, "because it isn't the thing that really represents the spirit of independence and the sovereignty of the individual which I feel should be represented in our edifices devoted to culture."

I was dumbfounded by the dexterity of Wright's response. In four sentences, one could detect the clarity of his mind, his unshakable vision, his willingness to think out of the box. The rest of his interview was just as compelling, as was the rest of Wright's life. He completed the designs for the Guggenheim Museum, his last work, in 1957, when he was 90 years old.

But I also was dumbfounded by something else. As I contemplated Wright's answers, I remembered Jim from the nursing home. He was the same age as Wright. In fact, most of the residents were. I suddenly was beholding two types of aging. Jim and Frank lived in roughly the same period of time. But one mind had almost completely withered, while the other remained as incandescent as a light bulb. What was the difference in the aging process between men like Jim and the famous architect? This question has bugged the research community for a long time. Investigators have known for years that some people age with energy and pizazz, living productive lives well into their 80s and 90s. Others appear to become battered and broken by the process, and often they don't survive their 70s. Attempts to explain these differences led to many important discoveries, which I have grouped as answers to six questions.

1) Is there one factor that predicts how well you will age?

It was never an easy question for researchers to answer. They found many variables, from nature to nurture, that contributed to someone's ability to age gracefully. That's why the scientific community met with both applause and suspicion a group of researchers who uncovered a powerful environmental influence. In a result that probably produced a smile on Jack La Lanne's face, one of the greatest predictors of successful aging was the presence or absence of a sedentary lifestyle. Put simply, if you are a couch potato, you are more likely to age like Jim, if you make it to your 80s at all. If you have an active lifestyle, you are more likely to age like Frank Lloyd Wright and much more likely to make it to your 90s.

The chief reason for the difference seemed to be that exercise improved cardiovascular fitness, which in turn reduced the risk for diseases such as heart attacks and stroke. But researchers wondered why the people who were aging "successfully" also seemed to be more mentally alert. This led to the obvious second question:

2) Were they?

Just about every mental test possible was tried. No matter how it was measured, the answer was consistently yes: A lifetime of exercise can result in a sometimes astonishing elevation in cognitive performance, compared with those who are sedentary. Exercisers outperform couch potatoes in tests that measure long-term memory, reasoning, attention, problem-solving, even so-called fluidintelligence tasks. These tasks test the ability to reason quickly and think abstractly, improvising off previously learned material in order to solve a new problem. Essentially, exercise improves a whole host of abilities prized in the classroom and at work.

Not every weapon in the cognitive arsenal is improved by exercise. Short-term memory skills, for example, and certain types of reaction times appear to be unrelated to physical activity. And, while nearly everybody shows some improvement, the degree of benefit varies quite a bit among individuals. Most important, these data, strong as they were, showed only an association, not a cause. To show the direct link, a more intrusive set of experiments had to be done. Researchers had to ask:

3) Can you turn Jim into Frank?

The experiments were reminiscent of a makeover show. Researchers found a group of couch potatoes, measured their brain power, exercised them for a period of time, and re-examined their brain power. They consistently found that when couch potatoes are enrolled in an aerobic exercise program, all kinds of mental abilities begin to come back online. Positive results were observed after as little as four months of activity. It was the same story with school-age children. In one recent study, children jogged for 30 minutes two or three times a week. After 12 weeks, their cognitive performance had improved significantly compared with pre-jogging levels. When the exercise program was withdrawn, the scores plummeted back to their pre-experiment levels. Scientists had found a direct link. Within limits, it does appear that exercise can turn Jim into Frank, or at least turn Jim into a sharper version of himself.

As the effects of exercise on cognition became increasingly obvious, scientists began fine-tuning their questions. One of the biggest-certainly one dearest to the couch-potato cohort-was: What type of exercise must you do, and how much of it must be done to get the benefit? I have both good news and bad news.

4) What's the bad news?

Astonishingly, after years of investigation in aging populations, the answer to the question of how much is not much. If all you do is walk several times a week, your brain will benefit. Even couch potatoes who fidget show increased benefit over those who do not fidget. The body seems to be clamoring to get back to its hyperactive Serengeti roots. Any nod toward this history, be it ever so small, is met with a cognitive war whoop. In the laboratory, the gold standard appears to be aerobic exercise, 30 minutes at a clip, two or three times a week. Add a strengthening regimen and you get even more cognitive benefit.

Of course, individual results vary, and no one should embark on a rigorous program without consulting a physician. Too much exercise and exhaustion can hurt cognition. The data merely point to the fact that one should embark. Exercise, as millions of years traipsing around the backwoods tell us, is good for the brain. Just how good took everyone by surprise, as they answered the next question.

5) Can exercise treat brain disorders?

Given the robust effect of exercise on typical cognitive performance, researchers wanted to know if it could be used to treat atypical performance. What about diseases such as age-related dementia and its more thoroughly investigated cousin, Alzheimer's disease? What about affective disorders such as depression? Researchers looked at both prevention and intervention. With experiments reproduced all over the world, enrolling thousands of people, often studied for decades, the results are clear. Your lifetime risk for general dementia is literally cut in half if you participate in leisure-time physical activity. Aerobic exercise seems to be the key. With Alzheimer's, the effect is even greater: Such exercise lowers your odds of getting the disease by more than 60 percent.

How much exercise? Once again, a little goes a long way. The researchers showed you have to participate in some form of exercise just twice a week to get the benefit. Bump it up to a 20-minute walk each day, and you can cut your risk of having a stroke-one of the leading causes of mental disability in the elderly-by 57 percent.

The man most responsible for stimulating this line of inquiry did not start his career wanting to be a scientist. He wanted to be an athletics coach. His name is Dr. Steven Blair, and he looks uncannily like Jason Alexander, the actor who portrayed George Costanza on the old TV sitcom Seinfeld. Blair's coach in high school, Gene Bissell, once forfeited a football game after discovering that an official had missed a call. Even though the league office balked, Bissell insisted that his team be declared the loser, and the young Steven never forgot the incident. Blair writes that this devotion to truth inspired his undying admiration for rigorous, no-nonsense, statistical analysis of the epidemiological work in which he eventually embarked. His seminal paper on fitness and mortality stands as a landmark example of how to do work with integrity in this field. The rigor of his findings inspired other investigators. What about using exercise not only as prevention, they asked, but as intervention, to treat mental disorders such as depression and anxiety?

That turned out to be a good line of questioning. A growing body of work now suggests that physical activity can powerfully affect the course of both diseases. We think it's because exercise regulates the release of the three neurotransmitters most commonly associated with the maintenance of mental health: serotonin, dopamine, and norepinephrine. Although exercise cannot substitute for psychiatric treatment, the role of exercise on mood is so pronounced that many psychiatrists have begun adding a regimen of physical activity to the normal course of therapy. But in one experiment with depressed individuals, rigorous exercise was actually substituted for antidepressant medication. Even when compared against medicated controls, the treatment outcomes were astonishingly successful. For both depression and anxiety, exercise is beneficial immediately and over the long term. It is equally effective for men and women, and the longer the program is deployed, the greater the effect becomes. It is especially helpful for severe cases and for older people.

Most of the data we have been discussing concern elderly populations. Which leads to the question:

6) Are the cognitive blessings of exercise only for the elderly?

As you ratchet down the age chart, the effects of exercise on cognition become less clear. The biggest reason for this is that so few studies have been done. Only recently has the grumpy scientific eye begun to cast its gaze on younger populations. One of the best efforts enrolled more than 10,000 British civil servants between the ages of 35 and 55, examining exercise habits and grading them as low, medium, or high. Those with low levels of physical activity were more likely to have poor cognitive performance. Fluid intelligence, the type that requires improvisatory problem-solving skills, was particularly hurt by a sedentary lifestyle. Studies done in other countries have confirmed the finding.

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Excerpted from Brain Rules by John Medina Copyright © 2008 by John Medina. Excerpted by permission.
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