How you use your brain throughout your life—to think, learn, and interact with people—is crucial to your brain health. But that’s only one of three elements that play a huge role in keeping your brain functioning normally for as long as possible. You also need a healthy diet and physical activity to keep your neurons nourished and your networks nimble.
In earlier chapters, we’ve looked at plenty of evidence in support of exercise and proper nutrition. Eating well is good for your cells, while eating poorly or too much damages them bit by bit. And exercise helps maintain many functions in your body, from your muscles all the way down to your mitochondria. Both of these factors also have a significant impact on the health of your brain.
There’s probably no clearer example of how dramatically food and fitness affect your cognitive health than a major study done with dogs. Studying canine cognition isn’t done just because dogs are man’s best friend. Dogs perform more complex cognitive strategies than many animals, have sophisticated brain structures, and develop many of the same age-related physical signatures of cognitive decline people do—including memory loss and conditions similar to Alzheimer’s disease in humans. They also process nutrients in much the way humans do. That makes them a great proxy for the study of aging in humans.
Dr. Elizabeth Head, neuroscientist at the Sanders-Brown Center on Aging at the University of Kentucky, looks at how diet, exercise, behavioral experiences, and vaccines work on dogs in order to develop a better understanding of how such factors might affect humans. In one especially revealing study, Dr. Head tracked the brain health of about 50 older beagles for 2 years. The dogs ranged in age from 7 to 11, or old enough that some of them were already showing signs of memory problems and brain deterioration. Head divided the dogs into four groups:
The last group got both the enriched diet and the behavioral enhancement.
Within a couple weeks, the dogs who were fed the diet alone had already started to show improvement in attention and their ability to learn. “We blinked and said, ‘that can’t be right,’” Head recalls.
But in subsequent weeks, as the dogs were tested further using various kinds of cognitive tests, the improvements not only lasted, they continued. And not just for this subset of dogs. The dogs who got the behavioral enhancements and exercise did even better than the dogs who ate only the special diet.
Most amazing, though, was that the dogs who got both the nutrient-rich food and the behavioral enrichments did best of all.
“They were so good after two years of treatment, they looked no different [from how they had in] the beginning,” Head says. “We had totally maintained their cognitive function over two years. They should have been going through a rapid phase of aging; we were essentially able to halt that.”
The results were revelatory in several ways; most encouraging to the researchers was realizing that the changes in the dogs’ behavior and diet interventions protected their brains in different ways. At the end of the study, the brains of the dogs fed the antioxidant diet contained fewer plaques, which are abnormal clumps of proteins that cause Alzheimer’s-like symptoms in dogs. The dogs who got more exercise and social enrichment, however, had just as many plaques as the control dogs who had no diet or behavior enhancements—yet they were still in much better shape cognitively than the control dogs. Why? Because the dogs who had been exercised and socially engaged, it turned out, had lost fewer neurons over the course of the study.
“‘They should have been going through a rapid phase of aging; we were essentially able to halt that.’”
That explains why the group of dogs who got both lifestyle improvements benefitted so much more than either group individually. They got the benefit not only of developing fewer brain plaques, but also of keeping more neurons intact, which enhanced their cognitive reserve. In other words, a good diet is good for you. Exercise is good for you. But the two together are greater than the sum of their parts.
This study clearly shows why making an effort to eat more fruits and vegetables, even if you’re already physically fit, will benefit you years or decades from now. Or why walking every day will improve how you age, even if you eat the healthiest of diets right now.
“All the things we did with the food, the exercise, everything, is easily done with people,” Head explains. “It’s these small changes over time, which as they come together, are hitting multiple pathways in your brain and let you really slow down the aging process.”
Many studies in humans have also targeted the impact of diet and exercise on brain health. For sheer simplicity and clarity of outcome, of course, it’s hard to beat Head’s dog experiment. But other research provides additional clues about what kinds of foods may help protect your cognitive future.
Clock-Cheater Tip
If you’re middle aged and already feel like your brain isn’t working as well for you, it probably isn’t—but it should be. Don’t ignore it: now is the time to start boosting your intake of vitamin-rich foods and taking steps to reduce your stress. And of course, talk to your doctor about it.
The importance of various micronutrients to brain health has been shown in numerous studies, for example. Some B vitamins influence levels of a particular amino acid in the blood associated with a greater risk of developing Alzheimer’s disease. Vitamin D, meanwhile, has been identified as playing a role in processing and cementing memories.
This is one of the main messages delivered in the books, talks, and examining room of Dr. Daniel Amen, psychiatrist, author of numerous books on the brain, and head of the Amen clinics. What you eat and how you live your life, he says, has a direct effect on how well your brain looks. Amen’s clinics use a type of brain imagery called a SPECT scan, which doesn’t show the structure of the brain, but instead shows the brain’s activity level. Some of the pictures are pretty alarming, such as those of 30- and 40-year-olds with what looks like clearly diminished brain activity.
But the before and after pictures are enough to make you throw out everything in your pantry. Once someone has gone through an Amen makeover, which involves getting totally immersed in healthy behaviors and high levels of nutrition, the SPECT pictures of his patients’ brains look remarkably improved, even after just a couple months. Their brains appear to be working better in every way.
“Alzheimer’s disease starts in the brain before people have any symptoms …. That should scare the socks off all of us,” Amen says. “At our clinics, … usually the brains I see look pretty lousy.”
In laboratories nationwide, scientists are finding clear evidence tying brain health to diet. A study conducted by researchers at Oregon Health and Science University in Portland, published in 2012 in the journal Neurology, showed that elderly subjects with higher levels of vitamins B, C, D, and E in their blood performed better on various cognitive, attention, and executive function tests. Other studies, meanwhile, have implicated low levels of certain vitamins as increasing one’s risk of developing dementia. Researchers have linked slight deficiencies in vitamins such as B12, B6, and folate, as well as vitamin D and the mineral magnesium to sometimes large jumps in the risk of experiencing early cognitive decline.
How do you get more vitamins into your blood? Easy—by eating more plant-based foods, especially fruits and vegetables. A study published in 2010 in the American Journal of Geriatric Psychiatry looked at the effect of fruit and vegetable consumption in a population of Swedish twins. The researchers used data on the twins that had been gathered 30 years before about their fruit and vegetable consumption. They then identified and tested as many of the twins as possible and found a clear pattern across the decades: subjects who had eaten more fruits and vegetables in middle age had a measurably lower risk of dementia 30 years later.
Other researchers are looking at the impact of healthy fats on brain health. Researchers at the University of California Los Angeles tested the blood of more than 1,500 elderly study participants, all free of dementia, for the presence of various vitamins, minerals, and omega-3 fatty acids. Then they measured their brains using MRI scans and tested everyone for cognitive function. The study participants with the lowest levels of omega-3 fatty acids in their blood not only had smaller brain volumes, they also generally scored lower on cognitive ability tests, including measurements of visual memory, problem-solving, and multi-tasking.
The results were published in 2012 in the journal Neurology and confirmed findings reported earlier, in 2006, by researchers at the USDA’s Human Nutrition Research Center on Aging at Tuft’s University in Boston. In that study, a good diet was found to have long-term benefits. Nearly 900 subjects free of dementia and ranging in age from 55 to 88 were ranked by the concentration of DHA, an omega-3 fatty acid, in their blood. When tested 9 years later, the participants who had had the highest levels of DHA in their blood at the beginning of the study period had a 47 percent lower risk of dementia than the other participants.
Clock-Cheater Tip
Don’t just look for ways to get more healthy fats in your diet, such as omega-3 fatty acids; look for ways to reduce unhealthy fats, too. Researchers at Oregon Health and Science University in Portland tested 104 elderly subjects with an average age of 87 and found that those with higher levels of trans fats in their blood performed worse on cognitive function tests and had smaller brain volume.
More studies are taking place all the time that evaluate the role specific foods can play in protecting against age-related brain deterioration. Here are three recent notable examples, all from 2012:
Berries: A study published in the Annals of Neurology analyzed cognitive function and food consumption among 16,000 nurses being studied in an ongoing epidemiological health survey. The research showed that women who regularly ate berries high in flavonoid antioxidants, such as blueberries and strawberries, lived an average of 21⁄2 years longer without cognitive impairment than study participants who didn’t eat berries.
Walnuts: A Spanish study published in the Journal of Alzheimer’s Disease showed that people who eat walnuts regularly score better on memory tests and have better overall cognitive function. Walnuts contain antioxidants and omega-3 fatty acids. The same study also found memory-preserving evidence for consumption of olive oil, coffee, and red wine.
Green tea: A Japanese study, published in the American Journal of Clinical Nutrition, found that Japanese seniors who drank the most green tea had the lowest prevalence of cognitive disability. Green tea is high in antioxidants.
These studies—and many more like them from the past decade and longer—are exciting to read and offer great guidance for easy ways to incorporate healthier foods into your diet that will make a big difference to your health for years to come. Start sprinkling walnuts on your cereal, have strawberries as a snack, or drink green tea after lunch, for example. But the studies are so varied, it’s hard to sum them up in a simple list. Taken together, they illustrate the power of a more nutritious diet in general, especially one with many plant-based foods, much like the diet Dr. Head fed to her study dogs.
Whatever fruits, vegetables, whole grains, or nuts you happen to find convenient and affordable, start eating them when you can. By doing that, you’ll be making microscopic changes to your cells that will help your brain stay healthier in the long run. It doesn’t matter if you can only do a little bit here or there at first—just get started now. The earlier you start, the more time you have to accumulate the benefits, one strawberry at a time.
“The earlier you start, the more time you have to accumulate the benefits, one strawberry at a time.”
Inflammation Information
Among the changes that positive dietary and exercise habits bring to your brain—and your body—is the suppression of inflammation. Chronic inflammation is a condition identified as a factor in aging and age-related diseases, yet it’s not well understood. The science is so new—even unclear—that some aging experts are unwilling to call inflammation a clear-cut risk factor in the aging process. Yet countless other scientists, doctors, and health experts regularly identify it as one.
What is clear is that inflammation appears in aging brains. What’s not so clear is the role it plays in developing brain disease and cognitive decline.
When most people think of inflammation, they think of their ankle swelling after twisting it or some other obvious response of the immune system to an injury. Chronic inflammation is more insidious: it’s a low-level but near-constant immune system response, at the cellular level, to damage inflicted on cells and tissues by oxidative stress, cell senescence, and cell death.
When poor lifestyle habits cause these kinds of microscopic damage, you can’t see it with the naked eye and probably won’t even notice it until it builds up enough that you’re visibly aging—or you get sick. But don’t be fooled; as soon as your less-than-ideal behaviors disrupt your body’s carefully balanced environment, damaged cells start releasing signaling proteins called cytokines that alert the immune system something is wrong. The immune system mobilizes to repair whatever damage it might find, and the process of repairing or cleaning out that damage causes microscopic inflammation.
Chronically poor lifestyle habits (overeating, for example, or not getting enough vitamins, minerals, and antioxidants) turn this cycle of damage and repair into a constant assault on your cells. This creates a continuous state of low-level inflammation wherever the damage is happening, or possibly throughout the body.
Testing for certain proteins in the blood, such as c-reactive protein, can detect the presence of inflammation. It’s a warning sign when c-reactive protein is elevated in your blood because it suggests systemic inflammation, or low-level tissue-swelling somewhere in your body. Over long periods of time, this kind of continued immune response is associated with greater risk of heart disease, cancer, and other conditions of aging.
But here’s the problem scientists are struggling with: does inflammation contribute to the development of disease, or is it just another repercussion of an unhealthy choice, such as smoking or eating too much fatty food? Many scientists would say the jury is still out on that. “There’s increasing evidence that it’s linked to aging, but it’s hard to pin down what’s going on,” says Dr. Brian Kennedy, president of the Buck Institute for Research on Aging.
Either way, it’s clear that if you have elevated levels of inflammation, something in your lifestyle isn’t right. Cellular damage is happening inside you, somewhere, and you should find a way to slow it down.
“If you have elevated levels of inflammation, something in your lifestyle isn’t right. Cellular damage is happening inside you, somewhere, and you should find a way to slow it down.”
This process of inflammation also happens in the brain. The brain doesn’t swell from chronic inflammation, but it does get an increased level of cytokines, protein molecules that are a marker for inflammation, explains Donna M. Wilcock, neuroscientist at the Sanders-Brown Center on Aging at the University of Kentucky. Those levels of cytokines are higher in the presence of dementia and Alzheimer’s disease, and scientists like Dr. Wilcock are trying to figure out why.
“We think what’s happening is there may be a two-hit process going on in Alzheimer’s disease, which is that if you have inflammation processes early in your life, from an unhealthy lifestyle, a bad diet, and a lot of chronic inflammation, then you start to develop some of the Alzheimer’s pathologies when you’re old,” she says. In other words, having chronic inflammation when you’re young makes you vulnerable to inflammation in the brain when you’re older, which appears to play a role in the development of Alzheimer’s disease and other types of cognitive impairment that comes with aging.
“If you can change the inflammation that’s happening in your body, you’re going to change the inflammation in your brain,” says Dr. Wilcock. “This is a whole body phenomenon.”
Brain Healing
How can you heal your brain? You need to start with an understanding of how the brain works and responds to the signals it gets and the nutrition it’s given. Hopefully, this chapter has clarified some of the factors that matter the most.
In a presentation at a 2012 brain health forum sponsored by the American Society on Aging, Dr. Paul D. Nussbaum, clinical neuropsychologist from the University of Pittsburgh School of Medicine, summed up five lifestyle components that lead to brain health:
You’ve read about the first four at length, and you’ll find plenty of useful tips at the end of the book on ways to get started in all these areas.
But what does Nussbaum mean by spirituality? He means inner peace—however you can achieve it. Too many people walk around feeling stressed, angry, and frustrated, which has obvious physical effects on cognitive health, as shown in Dr. Bennett’s studies on populations of older people.
Inner peace is about becoming just as aware of what’s going on inside your body as outside. “We’re not so good at that—a heart attack may feel like jaw pain or arm pain,” Dr. Nussbaum explains. “We don’t have the same sensitivity as we do when we see there’s a snake three inches from our leg.”
But it is possible to become more in tune with your body’s inner signals, once you shut off the faucet of stress. “Whether it’s deep prayer or deep meditation … that seems to bring the brain into an electrical state of stabilization,” he says. “It’s about how do we think about getting the brain to reduce its stress so that it functions in an efficient way. You’ll never maximize mental stimulation, or physical activity, or nutrition unless the brain is in a state where it can do what it does best.”