BY DR. DAVID PERLMUTTER, M.D. & ALBERTO VILLOLDO, Ph.D.
Neurogenesis: Growing New Brain Cells
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 (brain cells). 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 when it comes to the question of how to increase new brain cells, there’s a lot we can do to enhance this process.
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 increased BDNF when we consider its association with other neurological conditions, including epilepsy, anorexia nervosa, depression, schizophrenia, and obsessive-compulsive disorder.
How to Increase BDNF Production
We now have a very firm understanding of the factors that influence our DNA to produce BDNF and how to increase BDNF in the brain. Fortunately, these factors are by and large under our direct control.
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 fatty acid known as docosahexaenoic acid.
This is a powerful message because all of these factors that increase BDNF are within our grasp; they represent choices we can make to turn on the gene for neurogenesis. So let’s explore them individually.
1. Physical Exercise
One of the most efficient ways to increase BDNF is through 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, is a great way to take control of your brain health and mental destiny.
2. Calorie Reduction
Another factor that turns on the gene for increased BDNF 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.
In a 2009 study on how to increase brain cells naturally, 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.”
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. 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.
We hope that this data and the desire to help your brain turn on BDNF production will motivate you to follow a reduced-calorie diet. But, if you want to do more in achieving a healthy brain, you can implement a program of intermittent fasting.
3. Intellectual Stimulation
BDNF is described as a brain-derived 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 levels 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.
Being involved in stimulating mental activities—such as problem solving, exploring novel environments, and, perhaps most important, meditating regularly—increases BDNF levels 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 that could also help in the production of new brain cells. 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 levels.
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 levels. 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, the main active ingredient in the spice turmeric, is currently the subject of intense scientific inquiry, especially as it relates to the brain and how to increase BDNF. 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.
And 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 levels on brain neurons is at least part of the reason why those consuming curcumin are so resistant to this brain disorder.
5. Docosahexaenoic Acid (DHA)
Perhaps no other brain nutrient is receiving as much attention lately as DHA, especially after it was found to be a great way to increase BDNF. 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 healthy 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 to increase 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.
BDNF and Brain Protection
Now that you already have an idea on how to increase BDNF naturally, it is also worth noting that BDNF is important not only in neurogenesis and neuroplasticity but also in protecting delicate neurons from being damaged by a variety of insults, including trauma, transient reduction in blood supply, and, perhaps most important, environmental toxins. Indeed, in laboratory studies, rats and even primates with higher levels of BDNF are far more resistant to brain-damaging toxins than animals with low or normal levels.
Thus, turning on BDNF production through natural means and lifestyle decisions provides our brains with powerful protection against the ubiquitous onslaught of mitochondrial toxins, such as commonly used pesticides, to which we are exposed on a daily basis.
Excerpted with permission from Power Up Your Brain: The Neuroscience of Enlightenment by David Perlmutter and Alberto Villoldo. It is available online at hayhouse.com.