It is something of a cliché among runners, how the activity never fails to clear your head. Does some creative block have you feeling stuck? Go for a run. Are you deliberating between one of two potentially life-altering decisions? Go for a run. Are you feeling mildly mad, sad, or even just vaguely meh? Go for a run, go for a run, go for arun.
The author Joyce Carol Oates once wrote in a column for the New York Times that “in running the mind flees with the body … in rhythm with our feet and the swinging of our arms.” Filmmaker Casey Neistat toldRunner’s World last fall that running is sometimes the only thing that gives him clarity of mind. “Every major decision I’ve made in the last eight years has been prefaced by a run,” he told the magazine. But I maybe like the way a runner named Monte Davis phrased it best, as quoted in the 1976 book The Joy of Running: “It’s hard to run and feel sorry for yourself at the same time,” he said. “Also, there are those hours of clear-headedness that follow a longrun.”
A good run can sometimes make you feel like a brand-new person. And, in a way, that feeling may be literally true. About three decades of research in neuroscience have identified a robust link between aerobic exercise and subsequent cognitive clarity, and to many in this field the most exciting recent finding in this area is that of neurogenesis. Not so many years ago, the brightest minds in neuroscience thought that our brains got a set amount of neurons, and that by adulthood, no new neurons would be birthed. But this turned out not to be true. Studies in animal models have shown that new neurons are produced in the brain throughout the lifespan, and, so far, only one activity is known to trigger the birth of those new neurons: vigorous aerobic exercise, said Karen Postal, president of the American Academy of Clinical Neuropsychology. “That’s it,” she said. “That’s the only trigger that we knowabout.”
The other fascinating thing here is where these new cells pop up: in the hippocampus, a region of the brain associated with learning and memory. So this could help explain, at least partially, why so many studies have identified a link between aerobic exercise and improvement in memory. “If you are exercising so that you sweat — about 30 to 40 minutes — new brain cells are being born,” added Postal, who herself is a runner. “And it just happens to be in that memoryarea.”
Other post-run changes have been recorded in the brain’s frontal lobe, with increased activity seen in this region after people adopt a long-term habit of physical activity. This area of the brain — sometimes called the frontal executive network system — is located, obviously enough, at the very front: It’s right behind your forehead. After about 30 to 40 minutes of a vigorous aerobic workout – enough to make you sweat – studies have recorded increased blood flow to this region, which, incidentally, is associated with many of the attributes we associate with “clear thinking”: planning ahead, focus and concentration, goal-setting, timemanagement.
But it’s this area that’s also been linked to emotion regulation, which may help explain the results of one recent study conducted by Harvard psychology professor Emily E. Bernstein. Like Postal, Bernstein is also a runner, and was curious about a pattern she saw in her own mind after a run. “I notice in myself that I just feel better when I’m active,” she said. She started to become really interested in the intervention studies that have popped up in recent years that suggest if you can get people who are having trouble with mood or anxiety to exercise, it helps. “But why?” she wanted to know. “What is exercise actuallydoing?”
To find out, she did a version of a classic experiment among researchers who study emotion: She and her colleague — Richard J. McNally, also of Harvard — played a reliable tearjerker of a clip: the final scene of the 1979 film The Champ. Here, why don’t you watch it for yourself and try not tocry:
Before watching the film clip, some of the 80 participants were made to jog for 30 minutes; others just stretched for the same amount of time. Afterward, all of them filled out surveys to indicate how bummed out the film had made them. Bernstein kept them busy for about 15 minutes after that, and surveyed them again about how they were feeling. Those who’d done the 30-minute run were more likely to have recovered from the emotional gut-punch than those who’d just stretched — and, her results showed, the people who’d initially felt worse seemed to especially benefit from the run. Bernstein is currently doing a few follow-up research projects to determine exactly why this works the way it does. (In the meantime, it helps prove my poor boyfriend right, who, when I am not acting very nicely toward him, will often patiently ask me, “Hey, have you been on a run yettoday?”)
But there’s another big mental benefit to gain from running, one that scientists haven’t quiet yet managed to pin down to poke at and study: the wonderful way your mind drifts here and there as the miles go by. Mindfulness, or being here now, is a wonderful thing, and there is a seemingly ever-growing stack of scientific evidence showing the good it can bring to your life. And yet mindlessness — daydreaming, or getting lost in your own weird thoughts — is important, too. Consider, for example, this argument, taken from a 2013 article by a trio of psychologists in the journal Frontiers in Psychology:
We mind wander, by choice or by accident, because it produces tangible reward when measured against goals and aspirations that are personally meaningful. Having to reread a line of text three times because our attention has drifted away matters very little if that attention shift has allowed us to access a key insight, a precious memory or make sense of a troubling event. Pausing to reflect in the middle of telling a story is inconsequential if that pause allows us to retrieve a distant memory that makes the story more evocative and compelling. Losing a couple of minutes because we drove past our off ramp is a minor inconvenience if the attention lapse allowed us to finally understand why the boss was so upset by something we said in last week’s meeting. Arriving home from the store without the eggs that necessitated the trip is a mere annoyance when weighed against coming to a decision to ask for a raise, leave a job, or go back toschool.
Just because the benefits of losing yourself in your own thoughts are not easily measured doesn’t mean they’re not of value, and there are few ways I know of that induce this state of mind more reliably than a long run. A handful of recent studieshave tried to answer what every runner, whether pro or hobbyist, has no doubt been asked by friends and family: What on earth do you think about while you’re out there for so many miles? This, as the writer Haruki Murakami noted in his What I Talk About When I Talk About Running, is almost beside the point. Sometimes he thinks while on the run; sometimes, he doesn’t. It doesn’t really matter. “I just run. I run in void,” he writes. “Or maybe I should put it the other way: I run in order to acquire avoid.”
Boost your brainpower. Train your brain. These days it's hard not to become distracted by ads for the latest program that promises to help you learn faster and hold onto memories longer.
Run for your life! Regular aerobic exercise has been associated with increased cognitive abilities, including benefits to learning and memory. But, even as scientists continue to explore the effects of various brain-training programs, a wealth of evidence makes one thing quite clear: physical exercise benefits the brain. Over a decade of research in animals and people shows that engaging in regular aerobic activity leads to changes in the brain associated with improved cognition.
Exercise increases birth of new nerve cells
One of the earliest clues about exercise-induced changes in the brain came in the late 1990s, when a group of scientists decided to compare the brains of mice given unlimited access to an exercise wheel (runners) to those of mice without exercise wheels in their cages (non-runners).
Compared with the non-runners, the researchers discovered that physically fit mice had double the number of new nerve cells in a region of the hippocampus — an area of the brain involved in learning and memory. When the scientists later taught the runners and non-runners to navigate a water maze, they found the runners learned the task faster than the non-runners and took a more direct route to the maze end.
Fred Gage, a neuroscientist at the Salk Institute for Biological Studies who led both studies, explained that the researchers were "very surprised" to find that the physical activity of a mouse "affects the number of new brain cells and impacts its ability to remember things." At the time, scientists largely agreed the brain affects behavior. Gage's studies suggested the opposite was also true.
Exercising monkeys learn faster
Rodents are avid runners. In fact, with access to the exercise wheel, they will run for hours, racking up several miles each day. Since most people don't put in the hours or mileage running that rodents do, some scientists began to ask: Are long hours of aerobic activity required to see the positive effects of exercise on the brain, or might a more moderate exercise routine do the trick?
To test whether moderate exercise changes the brain, Judy Cameron, a neuroscientist at the University of Pittsburgh, trained a group of middle-aged and older monkeys to run on a treadmill for one hour each day, five days per week for five months — a running regimen similar to that recommended for average, middle-aged adults. As the one group of monkeys ran, a second group of monkeys sat on the treadmills. Over the course of the study the researchers evaluated the monkeys' ability to learn new things.
Regardless of the age of the monkeys, Cameron's group discovered that the monkeys on the running regimen learned new things twice as fast as the sedentary animals.
"We were excited to see that the same moderate level of exercise that is recommended for middle-aged people is able to improve how the brain works in monkeys — increasing alertness, attentiveness, and leading to faster learning," Cameron says.
According to Cameron, it's possible that the cognitive improvements associated with exercise are the result of increased blood flow to the brain. The greater the blood flow, the faster oxygen and other important nutrients can reach nerve cells.
When Cameron's group compared the brains of the monkeys that ran to the brains of sedentary animals they found that the older runners developed more brain blood vessels. However, when the scientists examined the brains of older runners that stopped exercising for three months, they found that the older runners had no more brain blood vessels than their sedentary counterparts.
"These findings suggest that it's important to keep exercising to retain the benefits of exercise," Cameron says.
Brain benefits across lifespan
Studies of animals and people show an association between physical activity and improved cognitive performance across the lifespan, says Art Kramer, who studies how fitness can change the aging brain at the University of Illinois at Urbana-Champaign. According to recent human studies, even people who hold off on regular aerobic activity until later in life may still be able to gain from exercise in their senior years.
As people get older, it is natural for some regions of the brain to begin to shrink. For instance, studies show the hippocampus shrinks one to two percent annually in people without dementia — a loss that is associated with an increased risk for developing cognitive difficulties. Curious about whether exercise could help slow or reverse these changes, Kramer and his colleagues recruited a group of healthy, sedentary adults from ages 55 to 80 to participate in a yearlong exercise program.
These adults were divided into two teams — one spent their time walking for 40 minutes three days per week while the other performed a variety of strength and balance exercises during this time. At the start, middle, and completion of the study, the researchers used magnetic resonance imaging (MRI) to measure the volume of the hippocampus.
The size of the hippocampus increased by 2 percent on average in the adults that completed the walking regimen and memory improved. In contrast, the participants who completed a yearlong balance and strength training program experienced a 1 percent decrease in the volume of the hippocampus.
"These findings suggest that brain and cognitive health can benefit from very modest increases in exercise and physical activity," Kramer says. "It's never too late to reap the benefits of exercise."
References
Colcombe SJ, Kramer AF, Erickson KI, Scalf P, McAuley E, et al. Cardiovascular fitness, cortical plasticity, and aging. Proceedings of the National Academy of Sciences USA. Mar 2; 101(9):3316-21 (2004).
Cotman C, Berchtold N, Christie L. Exercise builds brain health: key roles of growth factor cascades and inflammation. Trends in Neuroscience. 9: 464-72 (2007).
Eriksson P, Perfilieva E, Björk-Eriksson T, Alborn A, Nordborg C, et al. Neurogenesis in the adult human hippocampus. Nature Medicine. 4: 1313 – 1317 (1998).
Gómez-Pinilla F, Hillman C. The influence of exercise on cognitive abilities. Comprehensive Physiology. 3:403-428 (2013).
Haskell WL, Lee IM, Pate RR, Powell KE, Blair SN, et al. Physical activity and public health: updated recommendation for adults from the American College of Sports Medicine and the American Heart Association. Medicine and Science in Sports and Exercise. Aug;39(8):1423-34 (2007).
Pereira A, Huddleston D, Brickman A, Sosunov A, Hen R, et al. An in vivo correlate of exercise-induced neurogenesis in the adult dentate gyrus. Proceedings of the National Academy of Sciences. 13: 5638-5643 (2007).
Raz N, Lindenberger U, Rodrigue KM, Kennedy KM, Head D, et al. Regional brain changes in aging healthy adults: General trends, individual differences and modifiers. Cerebral Cortex 15:1676–1689 (2005).
Rhyu IJ, Bytheway JA, Kohler SJ, Lange H, Lee KJ, et al. Effects of aerobic exercise training on cognitive function and corticol vascularity in monkeys. Neuroscience. 4: 1239-1248 (2010).
van Praag H, Kempermann G, Gage F. Running increases cell proliferation and neurogenesis in the adult mouse dentate gyrus. Nature Neuroscience. 2: 266-270 (1999).
Voss M, Nagamatsu, L, Liu-Ambrose T, Kramer A. Exercise, brain, and cognition across the life span. Journal of Applied Physiology. 5: 1505-1513 (2011).
Further Reading
Ratey J. Spark: The Revolutionary New Science of Exercise and the Brain. Boston, 2008.
Jen Uscher is a freelance science writer based in Brooklyn, New York. She has written for ScientificAmerican.com, Popular Science, APA Monitor on Psychology, the Dana Foundation, the American Committee for the Weizmann Institute of Science, and the web site of the PBS science series NOVA.
Jennifer Carr is the former manager of science writing at the Society for Neuroscience. While working as a technician at a neuroscience lab at the University of Pennsylvania, Jennifer discovered she is happiest when communicating the excitement of scientific discovery to the general public. She has written for Kaiser Health News, The Scientist, and The Times-Picayune.
A lifetime of speaking two or more languages appears to pay off in old age, with recent research showing the symptoms of dementia can be delayed by an average of four years in bilingual people.
Multilingualism doesn't delay the onset of dementia—the brains of people who speak multiple languages still show physical signs of deterioration—but the process of speaking two or more languages appears to enable people to develop skills to better cope with the early symptoms of memory-robbing diseases, including Alzheimer's.
At Le Petit Paradis, preschoolers are learning their ABCs in both English and French. Aside from bilingualism's practical benefits, parents and experts alike say speaking multiple languages offer other advantages. WSJ's Christina Tsuei reports.
Scientists for years studied children and found that fluently speaking more than one language takes a lot of mental work. Compared with people who speak only one language, bilingual children and young adults have slightly smaller vocabularies and are slower performing certain verbal tasks, such as naming lists of animals or fruits.
But over time, regularly speaking more than one language appears to strengthen skills that boost the brain's so-called cognitive reserve, a capacity to work even when stressed or damaged. This build-up of cognitive reserve appears to help bilingual people as they age.
"Speaking two languages isn't going to do anything to dodge the bullet" of getting Alzheimer's disease or dementia, says Ellen Bialystok, a bilingualism researcher at York University in Toronto. But greater cognitive reserve means the "same as the reserve tank in a car: Once the brain runs out of fuel, it can go a little farther," she says.
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Specifically, the advantages of bilingualism are thought to be related to a brain function known as inhibitory or cognitive control: the ability to stop paying attention to one thing and focus on something else, says Dr. Bialystok. Fluent speakers of more than one language have to use this skill continually to silence one language in their minds while communicating in another.
The idea of building up cognitive reserve has led to the popular advice that doing crossword puzzles or brain teasers, anything to remain mentally active, helps stave off dementia symptoms. A panel convened by the National Institutes of Health in July cautioned, however, that there isn't enough evidence to conclude that such activities prevent Alzheimer's disease or related dementias.
Researchers don't know whether it is beneficial for people to learn more than one language if one doesn't speak them fluently or nearly every day. The age at which the second language needs to be acquired to yield the protective effect is also unknown.
ENLARGE
Tamar Gollan, a researcher on bilingualism at the University of California San Diego and at the university's Alzheimer's Disease Research Center, says people can, of course, learn a new language if they want to, regardless of age. "But there's no magic point," Dr. Gollan cautions.
Dr. Bialystok began her decades-long research by studying how children learn a second language.
In 2004, she and her colleague Fergus Craik shifted to conduct three studies looking at the cognitive effects in some 150 monolingual and bilingual people between 30 and 80 years old. They found that in both middle and old age, the bilingual subjects were better able to block out distracting information than the single-language speakers in a series of computerized tests. The advantage was even more pronounced in the older subjects.
Dr. Bialystok says other research also shows better performance from bilingual people on tests requiring cognitive control, such as when they are instructed to determine whether a sentence is grammatically correct, even if the content doesn't make sense. For example, in distinguishing, "apples grow on trees" from "apple trees on grow" and "apples grow on noses," the third sentence requires people to focus on the structure and suppress paying attention to the meaning of the words.
The findings from the 2004 study led Dr. Bialystok to wonder whether these benefits might help older people compensate for age-related losses in learning.
She and her colleagues examined the medical records of 228 memory-clinic patients who had been diagnosed with different kinds of dementia, two-thirds with Alzheimer's disease. The results, published in the journal Neuropsychologia in 2007, suggested that bilingual patients exhibit problematic memory problems later than those who only spoke one language.
Bilingual patients were, on average, four years older than single-language speakers when their families first noticed memory problems, or when the patient first came to the clinic seeking treatment.
Moreover, bilingual patients' memories were no worse than those of single-language speakers by the time they arrived at the clinic, and there was no difference in the length of time between the detection of symptoms and when the patients were first checked in.
In a subsequent study, Dr. Bialystok and her colleagues looked at brain images of monolingual and bilingual Alzheimer's patients at the same age and stage of disease. They found that the brains of the bilingual people appeared to be in worse physical condition. This suggests that bilingualism doesn't delay the disease process itself, but rather helps bilingual individuals better handle memory deficits, Dr. Bialystok says.
Their group has confirmed the finding in a further study that will be published later this year, says Dr. Craik, a senior scientist at the Rotman Research Institute of Baycrest, which is affiliated with the University of Toronto.
Other research, however, complicates the picture of the potential benefits of multilingualism. A recent review of the medical records of some 600 people at a Montreal memory clinic showed a protective benefit for people who were fluent in more than two languages and for bilingual people who learned French before they learned English.
English-only speakers, however, fared just as well as multilingual people who learned English first. This anomaly might be explained by the English-speakers' particular genetics, nutrition, stress levels and environmental exposure, says Howard Chertkow, a cognitive neurologist at Jewish General Hospital in Montreal and a professor at McGill University, one of the authors on the study.
Researchers in Europe, such as Wouter Duyck, a professor at the University of Ghent in Belgium, are also working on similar studies to replicate the effect in other bilingual populations.
Kids put in institutions have different brain compositions than kids in foster care
Childhood neglect leads to harmful changes in the brain,a new study says.
In new research published in the journal JAMA Pediatrics, researchers looked at brain differences between Romanian children who were either abandoned and institutionalized, sent to institutions and then to foster families, or were raised in biological families.
Kids who were not raised in a family setting had noticeable alterations in the white matter of their brains later on, while the white matter in the brains of the children who were placed with a foster family looked pretty similar to the brains of the children who were raised with their biological families.
Researchers were interested in white matter, which is largely made up of nerves, because it plays an important role in connecting brain regions and maintaining networks critical for cognition. Prior research has shown that children raised in institutional environments have limited access to language and cognitive stimulation, which could hinder development.
These findings suggest that even if a child were at a risk for poor development due to their living circumstances at an early age, placing them in a new caregiving environment with more support could prevent white matter changes or perhaps even heal them.
More studies are needed, but the researchers believe their findings could help public health efforts aimed at children experiencing severe neglect, as well as efforts to build childhood resiliency.
What would Stewart Little make of it? Mice have been created whose brains are half human. As a result, the animals are smarter than their siblings.
The idea is not to mimic fiction, but to advance our understanding of human brain diseases by studying them in whole mouse brains rather than in dishes.
"It's still a mouse brain, not a human brain," says Steve Goldman of the University of Rochester Medical Center in New York. "But all the non-neuronal cells are human."
Rapid takeover
Goldman's team extracted immature glial cells from donated human fetuses. They injected them into mouse pups where they developed into astrocytes, a star-shaped type of glial cell.
Within a year, the mouse glial cells had been completely usurped by the human interlopers. The 300,000 human cells each mouse received multiplied until they numbered 12 million, displacing the native cells.
"We could see the human cells taking over the whole space," says Goldman. "It seemed like the mouse counterparts were fleeing to the margins."
Astrocytes are vital for conscious thought, because they help to strengthen the connections between neurons, called synapses. Their tendrils (see image) are involved in coordinating the transmission of electrical signals across synapses.
Human astrocytes are 10 to 20 times the size of mouse astrocytes and carry 100 times as many tendrils. This means they can coordinate all the neural signals in an area far more adeptly than mouse astrocytes can. "It's like ramping up the power of your computer," says Goldman.
Intelligence leap
A battery of standard tests for mouse memory and cognition showed that the mice with human astrocytes are much smarter than their mousy peers.
In one test that measures ability to remember a sound associated with a mild electric shock, for example, the humanised mice froze for four times as long as other mice when they heard the sound, suggesting their memory was about four times better. "These were whopping effects," says Goldman. "We can say they were statistically and significantly smarter than control mice."
Goldman first reported last year that mice with human glial cells are smarter. But the human cells his team injected then were mature so they simply integrated into the mouse brain tissue and stayed put.
This time, he injected the precursors of these cells, glial progenitor cells, which were able to divide and multiply. That, he says, explains how they were able to take over the mouse brains so completely, stopping only when they reached the physical limits of the space.
Species cross
"It would be interesting to find out whether the human astrocytes function the same way in the mice as they do in humans," says Fred Gage, a stem cell researcher at the Salk Institute in La Jolla, California. "It would show whether the host modifies the fate of cells, or whether the cells retain the same features in mice as they do in humans," he says.
"That the cells work at all in a different species is amazing, and poses the question of which properties are being driven by the cell itself and which by the new environment," says Wolfgang Enard of Ludwig-Maximilians University Munich in Germany, who has shown that mice are better at learning if they have the human Foxp2 gene, which has been linked with human language development.
In a parallel experiment, Goldman injected immature human glial cells into mouse pups that were poor at making myelin, the protein that insulates nerves. Once inside the mouse brain, many of the human glial cells matured into oligodendrocytes, brain cells that specialise in making the insulating material, suggesting that the cells somehow detected and compensated for the defect.
This could be useful for treating diseases in which the myelin sheath is damaged, such as multiple sclerosis, says Goldman, and he has already applied for permission to treat MS patients with the glial progenitor cells, and hopes to start a trial in 12 to 15 months.
Still a mouse
To explore further how the human astrocytes affect intelligence, memory and learning, Goldman is already grafting the cells into rats, which are more intelligent than mice. "We've done the first grafts, and are mapping distributions of the cells," he says.
Although this may sound like the work of science fiction – think Deep Blue Sea, where researchers searching for an Alzheimer's cure accidently create super-smart sharks, or Algernon, the lab mouse who has surgery to enhance his intelligence, or even the pigoons, Margaret Atwood's pigs with human stem cells – and human thoughts – Goldman is quick to dismiss any idea that the added cells somehow make the mice more human.
"This does not provide the animals with additional capabilities that could in any way be ascribed or perceived as specifically human," he says. "Rather, the human cells are simply improving the efficiency of the mouse's own neural networks. It's still a mouse."
However, the team decided not to try putting human cells into monkeys. "We briefly considered it but decided not to because of all the potential ethical issues," Goldman says.
Enard agrees that it could be difficult to decide which animals to put human brain cells into. "If you make animals more human-like, where do you stop?" he says.
