Brain Regeneration:

 

How Humans Regrow Circuits in the Brain

David Perlmutter, M.D.

 

Only recently have researchers discovered the potential of the human brain and come to truly appreciate the positive implications of neuroplasticity—the brain's ability to create new neural networks—both for our individual health as well as for society in general.

We now understand how to harness our brain's neuroplasticity to enhance certain neural pathways. In essence, we can alter our brain function so that we can more fully access those areas that pave the way for freedom from trauma and destructive emotions; this also allows us to express the genes for health and longevity and even enlightenment.

Neuroscientists have come a long way over the past 25 years. They have replaced the once-accepted paradigm of the brain as a hardwired, fixed, and immutable organ with the belief in neuroplasticity, which celebrates its dynamic ability to learn, adapt, and change.

Changing Our Neural Networks

Through neuroplasticity, the brain is able to rewire neural pathways, and even establish new neural superhighways. When a person suffers a stroke and loses function in the right hand, for example, the brain can create new pathways that may allow the left hand to perform some of the functions previously done only by the right.

Neural networks are created by focused, engaged stimulation. It takes more than simple repetition to create neural networks. Professional athletes have long known that practice does not necessarily make perfect, because bad practice simply reinforces a less than ideal pathway in the brain. Likewise, repeating a prayer over and over without positive focused intention makes enlightenment less likely. If you want to experiment, try brushing your teeth or holding your fork with your nondominant hand and notice how much concentration is required to perform this simple task. Likewise, the practice of joy, kindness, and forgiveness take focused attention to develop, but the more you exercise them, the more easily and naturally they come.

Michael Merzenich, professor emeritus at the University of California, San Francisco, performed a series of experiments in the mid-1990s that demonstrate the need for focused attention in order to learn new skills and behaviors. In one experiment, he applied a tapping stimulus to the fingers of two groups of monkeys. When the rhythm of the tapping occasionally changed, monkeys in one group received a reward of juice for responding to the change. The other group of monkeys was not rewarded for responding. After six weeks, Merzenich examined the monkeys' brains. The animals who had paid close attention to the stimulus, waiting for the change in rhythm so they could collect their reward, exhibited profound differences in the areas of the brain associated with processing tactile stimuli. No such changes were seen in the brains of the monkeys who were not rewarded for paying attention to the stimulus even though the stimulus, the tapping on their fingers, was exactly the same for both groups.

This is another reason why all those pats on the back, gold stars, recognition ribbons, and colorful merit badges we earned as children are so important to the brain! Even if those once-cherished prizes are now collecting dust on a shelf or stored in a forgotten box in the closet, the brain still remembers and appreciates the positive reinforcement from that impressionable time.

As Merzenich pointed out, the choices you make actually do influence the physical structures, the neural networks, in your brain. He remarked, "Experience coupled with attention leads to physical changes in the structure and future functioning of the nervous system. This leaves us with a clear physiological fact … moment by moment we choose and sculpt how our ever-changing minds will work, we choose who we will be the next moment in a very real sense, and these choices are left embossed in physical form on our material selves." The need for focused attention is further affirmed by Joe Dispenza in his book Evolve Your Brain: "The key ingredient in making these neural connections… is focused attention. When we mentally attend to whatever we are learning, the brain can map the information on which we are focusing. On the other hand, when we don't pay complete attention to what we are doing in the present moment, our brain activates a host of other synaptic networks that can distract it from its original intention. Without focused concentration, brain connections are not made, and memory is not stored." So, attention matters, whether it is gentle meditation or the intense concentration of an athlete at a critical competitive moment. As Sharon Begley, an award-winning science writer, summarized in a Wall Street Journal article in 2007: "The discovery that neuroplasticity cannot occur without attention has important implications. If a skill becomes so routine you can do it on autopilot, practicing it will no longer change the brain. And if you take up mental exercises to keep your brain young, they will not be as effective if you become able to do them without paying much attention."

NEUROGENESIS: GROWING NEW BRAIN CELLS

On top of the finding that we can create new neural pathways into adulthood, a virtual revolution in neuroscience has been launched by the recent discovery of the process of neurogenesis, the ability of the brain to actually grow new neurons. Stem cell therapy, a hot button of political debate and the focus of leading-edge research, holds the promise of offering a powerful tool in neurodegenerative conditions. We now understand that the human brain is constantly undergoing its own "stem cell therapy" through the process of neurogenesis. Every moment of our lives, several critically important areas of our brains are being replenished with stem cells that are destined to become fully functional brain cells, and there's a lot we can do to enhance this process.

Because neurogenesis had been noted in various other animals, scientists in the 1990s were hard at it, trying to demonstrate that humans indeed retained the ability to grow new brain neurons. In 1998, the journal Nature Medicine published a report by Swedish neurologist Peter Eriksson titled "Neurogenesis in the Adult Human Hippocampus." Dr. Eriksson had finally succeeded in launching what was to become a revolutionary paradigm shift.

As Sharon Begley remarked in Train Your Mind, Change Your Brain, "The discovery [of neurogenesis in the adult human brain] overturned generations of conventional wisdom in neuroscience. The human brain is not limited to the neurons it is born with, or even the neurons that fill it after the explosion of brain development in early childhood. New neurons are born well into the eighth decade of life. They migrate to structures where they weave themselves into existing brain circuitry and perhaps form the basis of new circuitry."

Dr. Eriksson discovered that within each of our brains there exists a population of neural stem cells that are continually replenished and can differentiate into brain neurons. Simply stated, we are all experiencing brain stem cell therapy every moment of our lives, a concept that remains iconoclastic in a number of scientific circles. His Holiness the Dalai Lama has stated, "It is a fundamental Buddhist principle that the human mind has tremendous potential for transformation. Science, on the other hand, has, until recently, held to the convention not only that the brain is the seat and source of the mind but also that the brain and its structures are formed during infancy and change little thereafter."

The revelation that neurogenesis was occurring in humans and that we retain this ability throughout our lifetimes provided neuroscientists around the world with a fresh and exciting new reference point with implications spanning virtually the entire array of brain disorders. Alzheimer's disease, characterized by a progressive loss of brain neurons, had long eluded researchers seeking to develop ways to slow the inexorable decline in cognitive function that so devastates patients and families. But with the idea of actually regenerating brain neurons, a new level of excitement and hope was raised in scientists who were dedicated to studying this and other neurodegenerative disorders.

So, now that neurogenesis was proven to be ongoing in humans throughout our lifetimes, the question became clear: What influenced this activity? Moreover, what could be done to actually enhance this process? And the fundamentally important question: What can we do to grow new brain neurons?

BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF)

A major component in this gift of neurogenesis—and it is a gift to be revered— is a protein called brain-derived neurotrophic factor (BDNF), which plays a key role in creating new neurons. And it also protects existing neurons, helping to ensure their survivability while encouraging synapse formation—that is, the connection of one neuron to another—which is vital for thinking, learning, and higher levels of brain function. Studies have in fact demonstrated that BDNF levels are lower in Alzheimer's patients, which is no surprise, given our current understanding of how BDNF works.

But we gain an even greater appreciation for the health benefits of BDNF when we consider its association with other neurological conditions, including epilepsy, anorexia nervosa, depression, schizophrenia, and obsessive-compulsive disorder.

BDNF Activation

We now have a very firm understanding of the factors that influence our DNA to produce BDNF. Fortunately, these factors are by and large under our direct control. Increasing your production of BDNF and thus increasing neurogenesis while adding protection to your existing brain neurons doesn't require that you enroll in a research study to determine if some new laboratory-created compound will enhance BDNF production. The gene that turns on BDNF is activated by a variety of factors, including voluntary physical exercise—animals forced to exercise do not demonstrate this change—calorie reduction, intellectual stimulation, curcumin, and the omega-3 fat known as docosahexaenoic acid.

This is a powerful message because all of these factors are within our grasp; they represent choices we can make to turn on the gene for neurogenesis. So let's explore them individually.

Physical Exercise: Laboratory rats that exercise have been shown to produce far more BDNF than sedentary animals. But, interestingly, animals forced to exercise produce considerably less BDNF than those who voluntarily choose to spend time on the running wheel. Researchers have shown that there is a direct relationship between elevation of BDNF levels in the voluntarily exercising animals and their ability to learn.

With the understanding of the relationship of BDNF to exercise, researchers have examined the effect of physical exercise in humans, both apparently healthy individuals as well as persons at risk or already diagnosed with Alzheimer's. The findings have been fairly remarkable. In a recent paper, Nicola Lautenschlager of the University of Western Australia found that elderly individuals who engaged in regular physical exercise for a 24-week period demonstrated an astounding improvement of 1,800 percent in memory, language ability, attention, and other important cognitive functions, compared with an age-matched group not involved in the exercise program. The exercise group spent about 142 minutes exercising each week—about 20 minutes a day.

In a similar study, Harvard researchers found a strong association between exercise and cognitive function in elderly women and concluded, "In this large, prospective study of older women, higher levels of long-term regular physical activity were strongly associated with higher levels of cognitive function and less cognitive decline. Specifically, the apparent cognitive benefits of greater physical activity were similar in extent to being about three years younger in age and were associated with a 20% lower risk of cognitive impairment."

These and other studies clearly indicate that exercise enhances brain performance and is directly associated with increased production of BDNF. Simply by voluntarily engaging in regular physical exercise, even to a relatively moderate degree, you can actively take control of your mental destiny.

Calorie Reduction: Another factor that turns on the gene for BDNF production is calorie reduction. Extensive studies have clearly demonstrated that when animals are fed a diet with reduced calories, typically by around 30 percent, their brain production of BDNF soars, along with a dramatic enhancement in memory and other cognitive functions.

But it's one thing to read research studies involving rats in an experimental laboratory and quite another to make recommendations to human patients based on animal research. Fortunately, studies that show the powerful effect of reducing caloric intake on brain function in humans are now appearing in some of the most well-respected medical journals.

In a 2009 study, German researchers imposed a 30 percent calorie reduction on the diets of elderly individuals and compared their memory function with a group of a similar age who ate whatever they wanted. At the conclusion of the three-month study, those who ate without restriction experienced a small but clearly defined decline in memory function, while memory function in the group who consumed the calorie-reduced diet actually increased profoundly. In recognition of the obvious limitations of current pharmaceutical approaches to brain health, the authors concluded, "The present findings may help to develop new prevention and treatment strategies for maintaining cognitive health into old age.

What a concept. Preventive medicine for the brain. While the tenets of preventive medicine have seemingly taken hold in so many other areas of health care, from heart disease to breast cancer, for some reason the brain has always been left out. Gratefully, with these new research findings, that is changing.

Further evidence supporting the role of calorie reduction to strengthen the brain and provide more resistance to degenerative disease comes from Mark P. Mattson at the National Institute on Aging Gerontology Research Center, who reports, "Epidemiological data suggest that individuals with a low calorie intake may have a reduced risk of stroke and neurodegenerative disorders. There is a strong correlation between per capita food consumption and risk for Alzheimer's disease and stroke. Data from population-based case control studies showed that individuals with the lowest daily calorie intakes had the lowest risk of Alzheimer's disease and Parkinson's disease. In a population-based longitudinal prospective study of Nigerian families in which some members moved to the United States, it was shown that the incidence of Alzheimer's disease among individuals living in the United States was increased compared to their relatives who remained in Nigeria."

The Nigerians who moved to the United States were obviously genetically the same as their relatives who remained in Nigeria. Only their environment changed. And this research clearly focused on the detrimental effects on brain health as a consequence of the increase in calorie consumption.

While the prospect of reducing calorie intake by 30 percent may seem daunting, consider that Americans now consume an average of 523 more calories daily than in 1970. Current United Nations estimates show that the average American adult consumes 3,770 calories each day. In contrast, most health-care professionals consider normal calorie consumption (i.e., the amount of calories needed to maintain body weight) to be around 2,000 calories daily for women and 2,550 for men, obviously with higher or lower requirements depending on level of exercise. A 30 percent reduction of calories from an average of 3,770 per day provides 2,640 calories, still more than a normal minimum requirement. Much of the calorie increase in Americans comes from our overwhelming increase in sugar consumption. The average American now eats and drinks an incredible 160 pounds of refined sugar each year, which represents a 25 percent increase in just the last three decades. This becomes particularly troubling in light of animal research done at UCLA showing a strong link between "the typical diet of most industrialized Western societies rich in saturated fat and refined sugar" and reduced BDNF levels and, as expected, correspondingly reduced memory function.

Lowering sugar intake alone might go a long way toward achieving a meaningful reduction in calorie consumption; weight loss would likely be a side benefit. Indeed, obesity, in and of itself, is associated with reduced levels of BDNF, as is elevated blood sugar, a common consequence of obesity. Furthermore, increasing BDNF provides the added benefit of actually reducing the appetite.

Intellectual Stimulation: BDNF is described as a neuronal trophic factor, which means that it is a chemical that induces positive growth, health, and functionality in the target tissue—in this case, brain neurons. So it would only make sense to expect BDNF to increase when the brain is challenged. Just as muscles will gain strength and thus functionality when exercised, the brain also rises to the challenges of intellectually stimulating circumstances by becoming faster and more efficient as well as having a greater capacity for information storage.

These positive features are all facilitated by the increase in BDNF caused by stimulating activities. Inversely, it is likely that BDNF levels are low in individuals who spend several hours each day watching television, playing rote computer games, or otherwise engaged in mindless and passive activities.

An agile mind is also a good deterrent to help us avoid debilitating diseases associated with old age. Mark Mattson suggests that agility education and linguistics are two ways to keep an active, functional mind. He states, "In regards to aging and age-related neurodegenerative disorders, the available data suggest that those behaviors that enhance dendritic complexity and synaptic plasticity also promote successful aging and decrease risk of neurodegenerative disorders.

For example, there is an inverse relationship between educational level and risk for Alzheimer's disease; people with more education have a lower risk. Protection against Alzheimer's disease, and perhaps other age-related neurodegenerative disorders, likely begins during the first several decades of life, as is suggested by studies showing that individuals with the best linguistic abilities as young adults have a reduced risk for Alzheimer's disease. Data from animal studies suggest that increased activity in neural circuits that results from intellectual activity stimulates the expression of genes that play a role in its neuroprotective effects. Levels of several different neurotrophic factors, including BDNF, are increased in the brains of animals maintained in complex environments, compared to animals maintained under usual housing conditions."

Being involved in stimulating mental activities—such as problem solving, exploring novel environments, and, perhaps most important, meditating regularly— enhances BDNF production and creates a brain that is not only more resistant to deterioration but one that enables you to push the limits of day-to-day functionality. In this context, it is important to view meditation not as a passive activity but as an active, brain-stimulating exercise. Even among Alzheimer's patients, the rate of disease progression is dramatically slowed in those who engage in spiritual practices, which, again, is likely a consequence of increased BDNF.

Meditation helps us visit the complex environment of the inner mind as well as the universal energy field. And, not surprisingly, this might well be the most powerful stimulant for BDNF production. Meditation-induced production of BDNF should be looked upon as the fertile ground into which seeds of spirituality- induced enlightenment are planted and flourish.

Curcumin: Curcumin, the main active ingredient in the spice turmeric, is currently the subject of intense scientific inquiry, especially as it relates to the brain. But curcumin isn't new to the medical research. In fact, practitioners of traditional Chinese and Indian (Ayurvedic) medicine have used it for thousands of years. Curcumin is known to possess a variety of biochemical properties that include antioxidant, anti-inflammatory, antifungal, and antibacterial activities.

But it is curcumin's ability to increase BDNF that has attracted the interest of neuroscientists around the world. Interestingly, in evaluating villages in India, where turmeric is used in abundance in curried recipes, epidemiological studies have found that Alzheimer's disease is only about 25 percent as common as in the United States. There is little doubt that the positive effects of enhanced BDNF production on brain neurons is at least part of the reason why those consuming curcumin are so resistant to this brain disorder.

Curcumin also activates the Nrf2 pathway, a recently discovered "genetic switch" that works by turning on the genes to produce a vast array of antioxidants that protect mitochondria.

Docosahexaenoic Acid (DHA): Perhaps no other brain nutrient is receiving as much attention lately as DHA. Scientists have been aggressively studying this critical brain fat for the past several decades for at least three reasons.

First, more than two-thirds of the dry weight of the human brain is fat, and one quarter of that fat is DHA. From a structural point of view, DHA is an important building block for the membranes that surround brain cells. These membranes include the areas where one brain cell connects to another, the synapses. This means that DHA is involved in the transmission of information from one neuron to the next and thus is fundamental for efficient brain function.

Second, DHA is one of nature's important regulators of inflammation. Inflammation is responsible for a large number of brain maladies, including Alzheimer's, Parkinson's, attention deficit hyperactivity disorder (ADHD), and multiple sclerosis. DHA naturally reduces the activity of the COX-2 enzyme, which turns on the production of damaging chemical mediators of inflammation. This inhibits the enzyme and helps put out the fire in our brains. The third and perhaps most compelling reason for studying DHA is its role in modulating gene expression for the production of BDNF. Thus DHA helps orchestrate the production, synaptic connection, and viability of brain cells while enhancing functionality.

In a recently completed double-blind interventional trial called the Memory Improvement with DHA Study (MIDAS), some members of a group of 485 healthy individuals with an average age 70 and mild memory problems were given a supplement that contained DHA made from marine algae and some were given a placebo. After six months, not only did blood DHA levels double in the group who received the DHA but the effects on brain function, compared with those who received the placebo, were outstanding. The lead project researcher, Karin Yurko-Mauro, commented, "In our study, healthy people with memory complaints who took algal DHA capsules for six months had almost double the reduction in errors on a test that measures learning and memory performance versus those who took a placebo.… The benefit is roughly equivalent to having the learning and memory skills of someone three years younger."

Humans are able to synthesize DHA from a common dietary omega-3 fat, alpha-linolenic acid. But so little DHA is produced by this chemical pathway that many researchers in human nutrition now consider DHA to be an essential fatty acid, meaning that health maintenance requires a dietary source of this key nutrient. Data also show that most Americans typically consume an average of only 60 to 80 milligrams of DHA daily, less than 25 percent of what researchers consider to be an adequate intake of 200 to 300 milligrams each day.

While the important roles of diet and exercise are well accepted in relation to heart disease, for reasons that are not readily apparent these considerations are virtually ignored in relation to brain health. And yet, the scientific evidence confirming the importance of diet and exercise as lifestyle factors that can be modified to support brain health and function is both abundant and sound. Maintaining and enhancing brain health are obviously important goals, but keep in mind that these same dietary and lifestyle activities are your keys to directly influence the expression of your genes. They allow you to redirect the course of your genetic destiny.

 

This article is excerpted by permission from Power Up Your Brain: The Neuroscience
of Enlightenment by David Perlmutter, M.D., and Alberto Villoldo, Ph.D., published by
Hay House, Inc., 2011, 800-654-5126, www.hayhouse.com (.au, .co.uk, .co.za, .co.in).
David Perlmutter, M.D., is a board-certified neurologist and fellow of the American
College of Nutrition, and is internationally recognized as a leader in the field of
nutritional influences in neurological disorders. He is medical director of the Perlmutter
Health Center in Naples, Florida.

 


REFERENCES
1. Sharon Begley, Train Your Mind, Change Your Brain (New York, NY: Ballantine
Books, 2007), 158.
2. Ibid., 159.
3. Joe Dispenza, Evolve Your Brain: The Science of Changing Your Mind (Deerfield
Beach, FL: HCI Books, 2007), 193–94.
4. Sharon Begley, "How Thinking Can Change the Brain," Wall Street Journal, January
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5. Begley, Train Your Mind, Change Your Brain, 65.
6. His Holiness the Dalai Lama, "Foreword," ibid., vii–viii.
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