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"The single most dazzling advance has been the discovery that the brain can generate new cells." Parade Magazine, November 21, 1999
In The Lean Advantage, I responded to the question, "If you had to pick one thing as the key to success in bodybuilding, what would it be?" My answer was, in essence, "The mind." Successful bodybuilding--like success in life--takes determination and hard work. But the real key is your mind. You have to sift through all kinds of conflicting information on diet and training to decide what's best for you. Whatever your bodybuilding goal, you won't achieve it unless you put your mind to it. That's especially true as you grow older; you have to work harder--and smarter. You have to train your mind as well as your body.
The general perception is that mental ability, short term memory, for example, wanes with the passing of years. That's true to some extent for just about everybody, but a growing body of research indicates that how well we do mentally as we age is to a considerable extent within our control.
Stimulation Makes Brain Grow
In Challenge Yourself, I wrote about the work of Marion Diamond, an eminent neuroscientist at the University of California at Berkeley. Dr. Diamond says that brain cells do tend to shrink or grow dormant in old age, but that's mainly from lack of stimulation. If we introduce vigorous mental stimulation daily, even an older, developed brain can grow. In short, she believes that our mind, like our body, responds to challenge. Says Dr. Diamond, "I think the brain can decide its own destiny."
"That destiny is determined in the billions of neurons--the key cells that comprise most of the mass of the brain," science journalist Fred Warshofsky reports in Stealing Time, The New Science of Aging (TV Books, 1999), where much of the latest research is collected.
The brain cells, neurons, we are given at birth must last us for a lifetime. With one exception--it's important; we'll get to it shortly--nerve cells do not regenerate themselves. "Otherwise, at birth what you have is what you're going to get," says Arnold Scheibel, the husband and research partner of Marion Diamond.
New Connections Form
Although we have a finite number of neurons, our brain continues to develop throughout life by making and remaking neuronal connections. "A neuron," explains Professor Scheibel, "essentially matures by growing branches. The branches, or dendrites, are extensions of itself out into this space around it. This becomes the surface area on which connections, we call them synapses, are made."
That's important, because the synapses are where brain cells, neurons, talk to one another. A single neuron can communicate with hundreds of thousands of others, forming a complex network of branches to store and process ideas. "The greater the density of synapses, the greater the capacity for learning," writes Warshofsky.
As explained in Challenge Yourself, Dr. Diamond has shown by placing rats in enriched environments, were they are living together in large cages with many objects and mazes to explore, that brain cells grow significantly--even in ancient rats, the equivalent of 90-year-old humans. "We can change those nerve cells measurably in four days," says Diamond. "If you look at a microscopic level," adds Dr. Scheibel, "you can actually see changes beginning to occur...within 30 seconds... It can occur that quickly."
According to Fred Warshofsky, scientists now accept that the brains of older rats are changeable. "Enriching the environment enriches the brain," Warshofsky writes. Importantly, Marion Diamond and Arthur Scheibel are convinced that what's true for rats is true for humans. The key to good cognitive function, at any age, they believe, is novelty.
"There is a part of the brain which is built to detect novelty and alerts the rest of the brain, " said Scheibel. "And with that alerting comes new dendritic growth, new circuits, and so forth."
Exciting New Discovery
As noted earlier, there is one area of the brain which produces new cells. Exciting new research, published in the October 15, 1999 issue of the journal Science, demonstrates that this regeneration ability is more significant than previously believed.
Warshofsky explains in Stealing Time that cells in the hippocampus, a primitive part of the brain that controls basic functions, are continually replicated throughout life. It was assumed, however, that the new cells remained in the old brain.
Contradicted that long-held belief, new studies using macaque monkeys show that cells generated in the hippocampus are put to work in the neocortex, the center of the mind's ability to reason and think. Once the newly generated neurons arrive in the neocortex, they "plug in" and become a new part of the brain's central circuitry, according to a Princeton University brain research team. "This shows that there is a natural regenerative mechanism" in the mature brain, says Elizabeth Gould, head of the Princeton team.
Most experts believe the structure and function of the neocortex is very similar in all primates and that basic processes in the brain of monkeys are like those in humans. If monkeys can migrate neurons created in one part of the brain to another part, our brain can probably perform the same function.
Use It or Lose It
How can we make our brain perform at top capacity throughout life? Diamond and Scheibel say it boils down to "use it or lose it." In fact, they believe the phrase came from their work. "I remember at a cocktail party saying that for the first time to somebody," Marion Diamond told Warshofsky. "And they were really shocked that the brain could change at all. So we've been speaking about [use it or lose it] for over 30 years, and many people still don't believe that the brain will change positively with experience."
"Stimulation in general, by keeping curious, asking questions, wanting to learn for a lifetime, is essential," says Diamond. "But having the knowledge that your brain can change positively with aging helps tremendously. But we just say keeping curiosity, newness, and challenge. Not just taking the easy route... It is exceedingly difficult. But accepted it, work hard at it, and enjoyed the fruits of your labor."
Stanford University neurobiologist Dr. Robert Sapolsky told Warshofsky that retirement at 65 is "just a disaster for an awful lot of folks." Sapolsky says just "halting everything dead at that point" is bad, "but the other extreme of you just keeping working in exactly the same way until you die in your proverbial boots" can be just as bad.
Dr. Scheibel agrees. "It seems to me that when you finally decide it's time to stop what you're doing, you should have in mind some very exciting things that you want to do next. Again, as Marion says, newness, unusualness is the key here... It stimulates not only brain activity but brain growth."
Believe in Yourself
Fred Warshofsky says other scientists who have tried to discover what successful agers have in common, echo the points made by Diamond and Scheibel. "Intellectual enrichment is good for the brain." People who continue learning throughout life --like Marion Diamond's enriched rats--generally age well.
People who have a sense of control--those who believe that their brain can change positively with aging--tend to do better. Dr. Sapolsky calls this a sense of "self efficacy." That doesn't mean that they feel invulnerable, however. "They're not trying to control the impossible stuff," says Sapolsky. "They are accommodating to the inevitabilities of aging. But in the realms in which there is still something they can do, they go at it with a fighting spirit."
Mary Makes History
Warshofsky offers the case of 89-your-old Boston widow Mary Fasano as an example of what can be accomplished by someone with a continuing thirst for knowledge and a belief in self-efficacy.
After leaving school at 14 and working two jobs to put her children through college, she decided it was her turn.
"When I was 71-years-old," she recalls, "my husband had passed away and that was when the idea came to me that it was my turn to go to school. And somehow or another I never thought of my age, because I was always in good health. And it seemed as though I could do anything even at that age."
After completing high school, she decided to earn her college degree from Harvard University. "I worked hard at it, very hard, and as I got older, it became a little harder, and oh, it took a longtime, it took me 16 years."
Mary Fasano, at the age of 89, became the oldest person ever to earn a degree from Harvard. "And she's not finished yet," writes Warshofsky. "She's hoping to write her autobiography and she's taken up chess to keep challenging her mind."
Exercise Improves Mental Function
Challenging your mind and having a sense of control are only part of the story. Physical exercise plays a more important role in keeping the mind young than you might think. Exercise can benefit more than the body and the muscle structure. It can benefit the brain as well.
Dr. Carl Cotman, a professor of psychobiology and neurology at the University of California, Irvine, investigated a strongly protective chemical that the brain itself produces called Brain Derived Growth Factor, or BDNF. BDNF can protect dendrites from retreating and even helps them grow back. Research in rats had already shown that exercise increases the blood supply to the rat's brain. Cotman wondered if exercise alone would also increase the production of BDNF. "Just like a muscle gets stronger, maybe the brain can actually get stronger from exercise and keep its cells healthier," says Dr. Cotman.
He designed an experiment with rats, and found that exercise did in fact cause the brain to increase levels of BDNF. The biggest surprise was that the increase was not just in the motor areas. Exercise also increased BDNF in areas involved in thinking and learning.
"That gets really exciting," says Cotman, "because just plain old activity is actually doing something to keep the health of the cognitive areas of the brain up and active and in better health."
What about humans? To find out, Cotman divided 800 people from a large retirement community into two groups. Half exercised on a daily basis and the other half did not.
A battery of tests showed that those in the exercise group performed better mentally than the sedentary group. Exercise itself was associated with improved and higher mental function. In other words, exercise did more than increase blood flow to the brain. Cotman's experiment suggests that it also increased the amount of the brain's own chemicals that protect and repair neurons, leading over time to improved cognitive abilities.
"Do exercises such as the
Power Snatch, which require speed and coordination, produce more
BDNF than less demanding activities? I don't know, but I wouldn't be surprised."
The findings, according to Cotman, are perfectly consistent with the animal studies. "It's a nice thread from the beginning principle to the basic science level, up through humans."
Doctor Acts on Findings
More confirmation is required, but Dr. Cotman is not waiting. He's already acting on the results. "You know, if you find it you've got to believe it. And so I exercise regularly."
Fred Warshofsky sums up what many of our elders discovered long ago, and what science is now confirming: "The way to age well is through a life of intellectual challenge, healthy living, and plenty of exercise."
(Stealing Time is the companion book to the three-part documentary film of the same name, broadcast recently on PBS. To order the book, go to www.tvbooks.com. The video is available wherever videos are sold.)
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