Mary first came to see me complaining of high levels of stress at work, with bouts of depression and a declining memory. In her late 30s, she was head attorney for an iconic Fortune 500 company and had signs of metabolic syndrome: raised glucose, belly fat, high blood pressure and no libido.
Despite being highly competent, she had genuine insecurities about herself and her job performance, and never felt she was doing enough. After investigating her beliefs and spiritual life, I discovered that a cold, emotionally distant mother was at the center of her fragile sense of self-esteem.
This early relationship made all relationships seem dangerous, so she kept people at arm’s length. To feel loved and safe, she’d turned to ‘comfort foods.’ In fact, hers was a typical all-American diet, with high-sugar, high-carb, fast and fried foods as staples.
Mary engaged in therapy with me to heal her early wounds, but also made dramatic shifts simply by changing her diet. What she ate to feel comforted was the very stuff that made her susceptible to stress and depression, and even interfered with her memory and neurogenesis (creation of new neurons).
After six months, much of her belly fat melted away, but her mood change was most surprising to her. And adding fish oil, green tea, turmeric and blueberries to her new low-sugar diet clearly raised her rate of neurogenesis. “I was able to eat plenty of healthy, high-fat foods that I used to avoid like the plague; this took the edge off and made me feel calmer and more solid in myself,” she says. “My job stress barely seems like a big deal now, and depressive thoughts hardly even come anymore.”
Up until the late 1990s, neuroscientists had believed that the brain stopped making new brain cells in adulthood, and from then on, it was just one inevitable slide into decrepitude as brain cells died off, never to be replaced.
Then scientists discovered this was all wrong. What changed?
The brain keeps growing new brain cells throughout life. In the 1950s, medical science discovered that the brain is more malleable, adaptable and fluid than they thought. This neural plasticity allows the brain to make new connections between neurons and to heal itself, to some degree, after trauma and strokes.
More recently, we’ve learned that the brain’s adaptability and plasticity are even greater than suspected.
By the 1980s and 1990s, with better technology to measure the brain, more evidence emerged, pointing to new neuron formation in the hippocampus of adult nonhuman mammals. It had long been known that the hippocampus is involved in forming new memories and plays a critical role in reasoning and remembering, with hippocampal damage resulting in cognitive deficits and memory problems.
This has since been proven by countless studies of hippocampus-related injury and illness, as seen in Alzheimer’s disease and other kinds of dementia.
But the creation of new memories throughout our lives means that change is happening in the brain, suggesting plasticity and dynamism. This insight plus the possibility of neurogenesis in adults led pioneering neuroscientist Fred Gage, PhD, at the Salk Institute in La Jolla, California, to explore the hippocampus in a new way.
In the late 1990s, Gage and his team proved that, contrary to nearly a century of accepted wisdom, adult human brains do indeed create new brain cells.1
This groundbreaking discovery has since been confirmed many times over.
Gage’s findings shook the foundations of everything science thought it knew about the brain, exploding two myths about the brain and aging that had been unquestioned ‘facts’: that your brain stops growing in your early 20s; and after that, you only lose brain cells, so aging meant cognitive decline and memory loss.
The discovery that the brain continues to generate neurons changes our entire picture of aging, for if new brain cells can be made, then the brain can renew itself. What is key is the rate of new brain cell formation.
Rates of neurogenesis vary widely from one person to another. While some brains create new neurons at a rapid clip, most of us chug along at around the average rate, while some make new brain cells at one-fifth the average rate. Your rate of neurogenesis may be the single most important factor for a good quality of life.
In fact, your quality of life is directly proportional to your rate of neurogenesis, as high rates confer strong cognitive, emotional and physical advantages. When neurogenesis is high, you are engaged, expansive, fulfilling your potential. Your mind’s abilities are enhanced and your emotional vitality is strong. You are protected against stress and depression, and your immunity is robust. You feel good, your spirits are high and your outlook is positive.
Conversely, in study after study, low rates of neurogenesis are associated with poorer cognitive function; your brain shrinks, your life contracts, and you can only move toward memory loss, cognitive deficits, dementia, stress and anxiety, depression, loss of executive function and immunity, and myriad health problems.2
Consequently, what we call ‘normal aging’ is actually an artifact of a neurotoxic lifestyle that slows the brain down considerably more—and faster—than necessary. Neurogenesis usually slows and plateaus in middle age, then decreases even further in old age.
But this doesn’t have to happen. Neurogenesis can be increased at all ages with proper stimulation. It can even increase dramatically, with major boosts in cognition, mood and health. This is not just extending the brain’s best years, but actually enhancing the brain itself—something we never knew was possible until now.
You can increase your rate of neurogenesis by three to five times at any age. You can operate at a higher level of brain function in your 20s and 30s, and all the way into your 60s, 70s and beyond. You can improve your brain’s ‘aliveness’ and memory. Old age doesn’t have to mean steep decline.
We’ve all operated on the myth that our genes determine how we age and how long our brain stays sharp. But we now know that diet and lifestyle significantly outweigh our genetic inheritance.
Just after neurogenesis was discovered, researchers wondered if they could ‘jump-start’ the process to increase the rate. Gage and his team gave mice an “enriched environment,” including running wheels, areas to explore, nesting materials, other mice to interact and mate with, and sensory novelties and complexities, then monitored the effects. The results were startling. The “enriched environment” increased neurogenesis four- to fivefold.3
The part of the brain where new brain cells were formed grew from 300,000 brain cells to 350,000—or one-sixth more neurons than normal. But even more surprising was the powerful effect this increase had on the abilities of these mice.
The mice with the extra brain cells had strongly enhanced thinking ability and memory compared with their “normal neurogenesis” peers. They figured things out faster and
displayed superior all-around cognitive skills. In other words, they were smarter.
What’s more, these mice had much greater emotional resources, and were protected against emotional stress by having dramatically improved resistance to fear, stress and depression. These ‘super-mice’ had considerable cognitive and emotional advantages over their normal cage-raised peers.
Another unexpected finding was the consistently positive results regardless of age. When the enriched environment began in middle age, neurogenesis was increased fivefold; when it began in old age, the increase was three- to fivefold.4
Even more surprising was the importance of enriching the environment in different ways. Normally, 60–70 percent of new neurons soon die, but the enriched environment allowed almost all neurons to survive and develop. It was the complete change in lifestyle that yielded such powerful results.
This animal study may not apply to humans, although it has been reproduced many times. And neuroscientists have determined the particular effects that different environmental stimuli have on human neurogenesis and which may prevent new cell die-off.
The power of the hippocampus
While the brain is composed mainly of neurons, it also has glial cells, which help to hold neurons in place as well as protecting, cleaning and pruning the brain. Glial cells are continuously on the lookout for synapses and neurons that aren’t being used, so they can
At the same time, to cope with an ever-changing environment, new brain growth needs to focus on the most essential new elements of the inner and outer worlds. The hippocampus performs this task perfectly.
Although there have been reports of neurogenesis in other areas of the brain, the only sites where it is confirmed to happen are the olfactory bulb, which processes smells, and the hippocampus.
What is so remarkable about the hippocampus is that it’s central to all four levels of our humanness: the body, heart, mind and spirit.
New neurons produced by the hippocampus take about three to four weeks to mature. They then migrate to where they are needed in the hippocampus and integrate with neurons that have been there for decades.
Rather than growing neurons willy-nilly, the hippocampus makes new neurons that respond to the
stimuli that evoked them. The hippocampus is involved in:
• physical movement, exercise and spatial learning (body)
• mood and emotion, especially stress, anxiety, fear and depression (heart)
• cognition, learning and new memory formation (mind)
• spiritual practices, such as mindfulness, devotion and compassion (spirit)
The hippocampus is a master key that is centrally involved in all dimensions of human consciousness, and the ideal producer of new brain cells for brain self-renewal.
How to keep your brain healthy
Eat plenty of fresh vegetables and fruit. The best vegetables are low-carb with lots of fiber, which gives a ‘full’ feeling and keeps the digestive tract moving. Low-GI (glycemic index) fresh fruit (slowly converted to sugar), raw fresh salad vegetables and cooked (but never overcooked) vegetables should be the bulk of our diet.
High-quality healthy fats should ideally make up the majority of calories (but not the bulk) of foods eaten by most people. These include:
• omega-3s (from high-quality fish high in omega-3—avoiding those low in omega-3s or high in omega-6s or mercury—flaxseed, grass-fed beef,
eggs from pasture-raised chickens)
• monounsaturated fats (from extra virgin olive oil, avocados, nuts, seeds)
• medium-chain triglycerides (from extra virgin coconut oil)
• saturated fats (from grass-fed meat, pasture-raised eggs, milk, yogurt, cheese)
One healthy fat stands out as superior: coconut oil. Organic extra virgin coconut oil can improve cognition in Alzheimer’s sufferers.5 Anecdotal reports show significant improvements even in advanced Alzheimer’s patients taking 3 Tbsp daily, while its use as a preventive for Alzheimer’s is currently being studied. Some authorities recommend 1–3 Tbsp daily to prevent cognitive decline. Coconut oil is an excellent cooking oil, as it doesn’t oxidize at high temperatures. Cooking with butter or clarified butter (ghee) is another safe alternative to vegetable oils that are unhealthy even at low temperatures.
Reduce dangerous oxidized fats. Cook at lower temperatures, and avoid burned or charred meat, overcooked or powdered eggs, or powdered milk. Reduce or eliminate conventional grain-fed beef, fish with high mercury contents (swordfish, marlin, tilefish, shark, ahi, bigeye tuna) and fish high in omega-6 fats (tilapia, farm-raised fish). Avoid trans fats and most vegetable oils except extra virgin olive oil, which is better used cold than for cooking.
Lower sugar and carbohydrate intakes.High levels of sugar reduce neurogenesis sharply, and even ‘high-normal’ blood sugar levels are linked to smaller brain volumes, especially of the hippocampus, less gray matter and more cognitive decline in those over 60.6
All carbs are eventually converted to glucose. White and wholewheat flour are both converted to sugar within about the same amount of time, despite wholewheat’s better reputation. Starchy vegetables like potatoes, rice and yams have a high GI load that taxes our systems, and eat fruit high in fructose (mangoes, peaches, plums, persimmons, bananas, grapes, lychees) sparingly, if at all. Dried fruit is almost pure sugar and best avoided, while fruit and carrot juices are similar in sugar content to soda drinks and are best omitted.
Opt for carbs with lots of fiber (squash, berries, carrots, string beans, kale, broccoli, cauliflower), as the body needs time to break down the fiber and liberate the sugar; this time lag prevents the sugar and insulin spikes behind insulin resistance.
Increase the time between meals and do intermittent fasts (an early dinner and late breakfast provides more than 12–14 hours of fasting). Increasing the time between meals raises levels of brain-derived neurotrophic factor (BDNF), a neural growth factor, and the rate of neurogenesis,7 and increases insulin sensitivity. Intermittent fasting can also improve metabolic syndrome, which is linked to cognitive decline.8
Avoid alcohol and caffeine. Moderate alcohol consumption reduces neurogenesis by 40 percent and BDNF levels too,9 while binge-drinking in adolescence may have significant effects on neurogenesis and BDNF levels well into adulthood.10
As for caffeine, even low or “physiologically relevant doses” (anything you can feel) can reduce neurogenesis and impair memory.11 So try drinking less caffeine or even stopping completely. You’ll adjust within a few weeks and wonder what the big deal was. Taking extra B5 and B12 vitamins can help, as these are ‘psychic energizers.’
Avoid deficiencies in zinc, vitamin A, thiamine and folic acid (B1 and B9). When we’re low in these vitamins and minerals, neurogenesis slows, but returns to normal when we supplement or re-establish healthy levels.7
Opt for chewy food. Eating soft foods (ice cream, processed foods, puddings, jelly, mashed potatoes, overcooked vegetables, bananas) reduces neurogenesis, while liquid foods reduce the survival of new brain cells. A diet of solid foods that need chewing increases neurogenesis, BDNF and memory.12
Get moving (and slightly out of breath). Aerobic exercise is best for neurogenesis—at least in animal studies.13 Whether it’s running, brisk walking, cycling, dancing, swimming, water-running, cardio classes, soccer, tennis or hiking, if it gets you breathing fast and hard, it’s aerobic, and it reduces the brain protein BMP (bone morphogenetic protein), which slows neurogenesis and keeps neural stem cells in a kind of cellular ‘sleep.’ But according to The New York Times (7/7/2010), just one week of running in wheels reduced BMP by 50 percent in mice, while increasing the wonderfully named protein Noggin, which
Mice with Noggin-infused brains became, according to researcher Dr Jack Kessler, “little mouse geniuses.” These mice breezed through the intelligence tests and mazes they were given.
Aerobic exercise also accelerates the heart, so more blood is pumped throughout the body.
And increased blood flow is a requirement for neurogenesis. When new brain cells develop, they need a good blood supply to help them grow. One indication that neurogenesis is taking place is an increased blood flow as measured by neuroimaging.
But aerobic exercise has positive effects beyond increasing blood flow, including anti-inflammatory, antioxidant and hormonal changes, all of which help brain function. Beginning aerobic exercise in middle age stops the age-related decline in neurogenesis,
keeps BDNF levels high and improves memory.14
A US study of older adults recently showed that exercise protected those most at risk (through a gene allele) of developing Alzheimer’s, and prevented both the memory loss and hippocampal shrinkage that non-exercisers had.15
Tips for boosting brain power with exercise
Walking. Start with a 20- to 30-minute walk three or four times a week, then try walking a little faster and a little longer, slowly increasing the time to 40–60 minutes. As neuroscientist Fred Gage, PhD, said, “Even a fairly short period and a short distance seems to produce results.”
Running. It’s well known that serious blows to the head slow neurogenesis, damage the connections between neurons and increase the chances of developing Alzheimer’s. But smaller shocks can also injure the brain—though this is where the science is lagging. As we don’t know what effects such mini-shocks (such as when jogging) may have on brain function, we can only be guided by common sense, and it’s clear that some forms of running are harder on the brain than others.
Given that we want to protect the brain as much as possible, it is probably wise to run so that the forefoot and toes touch the ground first, rather than the classic ‘heel strike’ that most people learned as children, while ‘chi running’ is another approach to low-impact running that emphasizes the mid-foot touching down first instead of the heel strike.
‘Gentle running’ and other popular approaches stress the importance of landing softly on the ground.
The easiest way to learn how to do this is to run barefoot in a gym so that the outside ball of your foot and toes hit the floor first.
Allow your legs to act as shock absorbers by bending at the knees to further cushion your stride. Keep your body fairly upright rather than leaning forward too much. Allow your foot to glide softly onto the ground and then gently slide off the ground in one continuous motion, so your legs further absorb the impact. Build up slowly and stop if you feel pain.
Biking. The leading cause of permanent brain damage from athletic sports in the US is biking accidents. Only half of cyclists wear a helmet regularly, and most helmets use obsolete technology that fails to protect against the most common brain injuries from biking accidents.
‘Shear strain’ on the brain due to acceleration with rapid changes of direction is the most common cause of concussion from a bike accident, yet most helmets only prevent linear acceleration. It’s also better to use a helmet that protects your brain against the widest range of accidents instead of one that is simply fashionable.
And if you love mountain biking, be careful on the hard landings coming downhill and the sudden jolts that inevitably happen. Use your legs, arms and upper body as shock absorbers.
Excerpted from The Neurogenesis Diet and Lifestyle: Upgrade Your Brain, Upgrade Your Life (Psyche Media, 2015) by Brant Cortright, Ph.D. Available from Amazon.
Superfoods for growing brain cells
Blueberries. These fruit are packed with polyphenols, especially flavonoids called ‘anthocyanins,’ pigments that give these berries their dark blue color, which cross the blood–brain barrier to stimulate neurogenesis. People suffering from cognitive decline show improvement after consuming blueberries every day,1 most likely because polyphenol antioxidants are strongly neuroprotective.2
Suggested daily dosage: 8 oz (1 cup) a day or the equivalent in extract Vitamin E.
Suggested daily dosage: 200–800 IU/day (as mixed tocopherols)
Omega-3 fatty acids. Our brains are 60 percent fat, and the omega-3 fatty acids, the best kind of dietary fat, increase neurogenesis by a whopping 40 percent, elevate BDNF (brain-derived neurotrophic factor) levels and increase brain size, among other neuroprotective benefits.3
Suggested daily dosage: 2–4 g/day
Green tea. Polyphenols in green tea improve working memory, among the most difficult cognitive functions to boost.4
Suggested daily dosage: 3–10 cups of green tea daily (but without the equivalent amount of caffeine)
Goji berries (wolfberries). These tasty dried berries from the Himalayas, long known for their powerful antioxidant properties, also have potent neurogenesis-stimulating effects.7
Suggested daily dosage: 500 mg once or twice daily (as dried berries or a 60 percent standardized extract)
Curcumin. Aging populations that consume curcumin (as in curries) have better cognitive function and significantly better scores on the Mini-Mental State Examination (MMSE).5
Suggested daily dosage: 200–1,200 mg/day (but as very high dosages may be toxic to cells, experiment to find what’s right for you). As this spice is poorly absorbed, add 10 mg of 95 percent
piperine (pepper) extract once or twice a day, or phospholipids like lecithin to enhance bioavailability
Grape seed extract. Beneficial for the heart and circulatory system, this can also increase brain cell growth.8
Suggested daily dosage: 100 mg once or twice daily (as a 90 percent polyphenol standardized extract)
Ginkgo biloba. This herb increases neurogenesis and enhances cognitive function, as well as reduces beta-amyloid plaque in Alzheimer’s sufferers.6
Suggested daily dosage: 120 mg/day of standardized extract
Quercetin. This yellow flavonoid pigment, found in onions, apples and red wine, among many other foods, increases neurogenesis dose-dependently.6
Suggested daily dosage: 500 mg once or twice daily
Lithium. This mineral, ordinarily used at high doses to treat bipolar disorder, can increase BDNF levels in the brain when taken in smaller amounts.
Suggested daily dosage: 5 mg/day (but adjust if it makes you sleepy).