John J. Ratey, MD

How Exercise Revs Up Your Brain U.S. News & World Report

April 17, 2008 12:09 PM ET | Katherine Hobson | Permanent Link

When I'm in a blue funk, going for a run helps me feel a lot better. And prolonged periods of inactivity—say, after a big race—make me anxious, and something close to depressed. There are certainly a host of reasons why exercise seems to improve my mood (the Justin Timberlake on my iPod and the view from the Brooklyn Bridge, for example), but one potential factor is the idea, supported by a growing body of research, that physical exertion itself has a much bigger influence on the brain than previously thought. Just this week, a survey of existing research published by the Cochrane Library concluded that the same aerobic exercise that is good for your heart also improves cognitive function—specifically, motor function, auditory attention, and memory—in healthy older adults.

That's only one piece of what has become a burgeoning field. In Spark: The Revolutionary New Science of Exercise and the Brain, published earlier this year, psychiatrist John Ratey explores the neuroscience behind potential beneficial effects of aerobic exercise on anxiety, stress, depression, learning, aging, and even attention deficit disorder. (Research hasn't as fully explored the effects of anaerobic exercise or more passive activities like stretching and yoga.) "Even people who are overweight and who start exercising see improvements in mood and cognition in as little as 12 weeks," he says. One study found that exercise improved depression symptoms as well as medication.

A host of mechanisms are thought to be responsible. As U.S. News reported earlier this year in a story about keeping your brain fit, studies in rodents showed that running led to an increase in new brain cells in a part of the brain called the hippocampus that plays a large role in learning and memory. Researchers don't count brain cells in studies of live humans, but one study of regularly exercising adults did show increased blood flow to the same area. Because of the obvious implications for age-related memory lapses and dementia, much of the human research in this area has been in the elderly, says Henriette van Praag, a researcher in the neuroplasticity and behavior unit in the laboratory of neurosciences at the National Institute on Aging. She's now studying (in rodents) whether the progression of neurodegenerative diseases like Alzheimer's can be slowed by exercise.

Some studies have looked at kids. They haven't yet shown that getting exercise causes improvements in concentration and learning, but "what we agree on at this point is that there's a strong association between aerobic fitness and performance on standardized testing, grades, and other measures of cognitive performance," says Darla Castelli, a researcher in the department of kinesiology and community health at the University of Illinois-Urbana-Champaign. She was an investigator on a study published last year in the Journal of Sport & Exercise Psychology that looked at the relationship between physical fitness and academic performance in 259 third and fifth graders. Aerobic exercise (as well as BMI) was related to achievement in reading and math. Now she's preparing to start a study in August that will compare cognition in a group of kids who participate in an after-school physical activity program with a group that does not.

Chemicals influenced by exercise, including neurotransmitters and growth factors, are being investigated for their role in mood and brain function. Even runner's high, that elusive euphoria that some people experience after prolonged or intensive running, is becoming clearer—literally. A study done in Germany, published in March in Cerebral Cortex, used PET scans to look at the brains of 10 athletes following a two-hour run. The scans confirmed that during the run, endorphins were released in certain parts of the brain known to be involved with the processing of emotions. But while endorphins may cause the runner's high, they're not the sole regulators of mood and emotions during a workout. "A lot of things contribute to us feeling better when we exercise," says Ratey. "Endorphins are one of them, but so are norepinephrine, serotonin, dopamine, and brain-derived neurotrophic factor (BDNF)."

So you're sold. How much do you need to work out to get these fabulous brain benefits? "Something is better than nothing," says Ratey. As little as 10 minutes of brisk walking can quench the urge for a cigarette for over an hour, he says, and Castelli notes that a single 10-minute bout of physical activity in an academic setting boosts attention and problem-solving skills in kids. A study published online earlier this month in the British Journal of Sports Medicine found that mental health benefits were observed after 20 minutes of physical activity, though the more exercise and higher intensity, the better the effects. Which means that doing the recommended 30 minutes a day of aerobic activity will cover your brain as well as your heart.

http://www.usnews.com/blogs/on-fitness/2008/04/17/how-exercise-revs-up-your-brain.html

John's Comments

Since Spark was published there have been a number of new studies that support the fact that exercise improves cognition in school children. Most recently a study from the CDC shows that especially in girls those that had the most physical activity per week consistently scored higher on tests with the greatest impact on math scores.

http://www.usatoday.com/news/health/2008-03-04-phys-ed-study_N.htm

Another study looking at the effects of 20 and 40 minutes a day of exercise showed an improvement on executive function scores and possibly on math tests in both boys and girls who participated in a study to help see how exercise can help reduce obesity in our children.

http://www.eurekalert.org/pub_releases/2007-10/mcog-eit102207.php

Anecdotal studies are pouring in and larger more well planned studies are underway to further study the effect of exercise on cognition in children, a fact that has been studied and deemed so in the elderly by a report out yesterday by the Cochrane Library an international organization that evaluates medical research . This report by a very conservative and  cautious review board now deems that along with the obvious positive  effects on the body,  taking up exercise improves the cognitive function in people over 55 years of age, regardless of whether or not they show  signs of cognitive impairment.

http://www.news-medical.net/?id=37449

http://mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD005381/frame.html

Third Age: Health and Wellness

Train Your Brain

 

  By Simon Usborne

We don't need to be told that exercise is good for us. We know that it combats cholesterol, we know boosts our hearts and we know it stops the pounds from piling on. But, beyond the obvious physical benefits of a good cycle, run or swim, a growing body of evidence suggests that getting breathless can also build the brain.

"Spark: The Revolutionary New Science of Exercise and the Brain," which will be published later this year, shows how even regular brisk walks can boost memory, alleviate stress, enhance intelligence and allay aggression. John Ratey, an associate professor of psychiatry at Harvard Medical School in Boston and the book's author, says that exercise stimulates our gray matter to produce what he calls "Miracle-Gro" for the brain. "I can't understate how important regular exercise is in improving the function and performance of the brain," he says. "It's such a wonderful medicine."

Happiness
If the mere thought of trudging round ice-bound playing fields at school was enough to bring you out in a cold sweat, the idea that exercise makes us happy might sound perverse. But, beyond the (potential) mood-lifting effects of fresh air and scenery, evidence suggests that pounding the pavement can also change the way our brains work to make us happier, or even stave off depression. "Exercise is as good as any anti-depressant I know," Ratey claims.

Last December, scientists from Yale University wrote in the journal Nature Medicine that regular exertion affects the hippocampus, the area of the brain responsible for mood. Tests on mice showed that exercise activated a gene there called VGF, which is linked to a "growth factor" chemical involved in the development of new nerve cells. Tests show that this brain activation lifts a person's mood. Participants in one recent German survey were asked to walk quickly on a treadmill for 30 minutes a day over a 10-day period. At the end of the experiment, researchers recorded a significant drop in depression scores. Scientists are now working on a drug that mimics the effects of the VGF gene to market it as an alternative to conventional antidepressants.

Stress
If, by around 4pm, it feels as if a stressful day at work has turned your brain to blancmange, it might not only be due to overwork or a shortage of double espressos. We respond to stress in the same way our ancestors did -- by adopting a "fight or flight" response. Adrenalin and other hormones are released into our bloodstreams and our muscles are primed for response. The problem is that, these days, stress is more likely to be brought on by a tricky PowerPoint presentation or a job interview than an attack by marauding lions, so the toxins that build up for a physical response have no outlet. The results can be good; the cardiovascular system is accelerated and we can work harder (for a while, at least), but others are not so good; stress slows down the gastrointestinal system and reduces appetite, and can overexcite the brain, fuzzing our thought. By responding to or anticipating stress with fight (kickboxing or judo, say) or flight (30 minutes on the treadmill, say, or 50 lengths of the pool), blood flow to the brain is increased, allowing the body to purge the potentially toxic by-products of stress. According to Ratey, exercise also helps in the long term. "It builds up armies of antioxidants such as Vitamins E and C," he says. "These help brain cells protect us from future stress."

Intelligence
Observers of sports might refute the claim that exercise leads to greater intelligence -- and they would be partly right, says Ratey. "Exercise doesn't make you smarter, but what it does do is optimise the brain for learning."

Physical activity boosts the flow of blood to the part of the brain that is responsible for memory and learning, promoting the production of new brain cells. Several schools in the U.S. and the Netherlands have taken note. Pupils at Naperville Central High School near Chicago, for example, start the day with a fitness class they call "Zero Hour PE". Equipped with heart monitors, they run laps of the playground, and teachers say exam results have soared since the keep-fit initiative kicked off.

Meanwhile, in Amsterdam, a test involving 241 people, aged 15-71, compared physical activity with the results of cognitive tasks. The researchers documented improved results among people who were more active, especially those in younger age groups.

Yet more research suggests that exercise boosts intelligence in the very, very young. Experiments on rats at the Delbrck Centre for Molecular Medicine in Berlin showed that baby rats born to mothers who were more active during pregnancy had 40 percent more cells in the hippocampus, the area of the brain responsible for intelligence. If the same is true in humans, we can expect Paula Radcliffe's baby, Isla, to be a genius; Radcliffe was training for the New York marathon until the day before she went in to hospital to be induced -- and won the race just nine months after giving birth.

Aggression
A few rounds with a punching bag or a game of squash are great ways to release pent-up aggression, but exercise does more than "get it out your system," says John Ratey. "People assume exercise reduces aggression by burning energy. In fact, exercise changes your brain so you don't feel aggressive in the first place."

The frontal cortex is the part of the brain that decides whether you throw a punch or take something on the chin. Reduced activity in the region, a trauma or abnormal development can result in an inability to control violent urges. "This area makes us evaluate the consequences of our actions," Ratey says. "It's the part of the brain that puts the brakes on when the ref makes a terrible decision and you want to beat him up." Exercise increases activity in that area, boosting rational thought, which makesus less likely to lash out.

Memory
Most of the competitors at the annual World Memory Championships could hardly be described as the epitome of physical fitness but, according to Ratey and other scientists in the field, a good workout does much to boost recall, especially as we clock up the years.

"When we're exercising, we're using nerve cells in the brain which help build up what I call brain fertilizer," he says. Ratey is talking about new research that suggests exercise increases blood flow to the part of the brain responsible for memory, and improves its function. In MRI scans on mice, conducted last year by neurologists at Columbia University Medical Center in New York, the animals were shown to grow new brain cells in the dentate gyrus, which is affected in age-related memory decline.

Research on humans is ongoing but Ratey is convinced that physical activity has a similar effect. He says: "Exercise does more than anything we know of to boost memory."

Addiction
Smokers keen to quit cigarettes probably won't celebrate the news that exercise could be the key to a cigarette-free life. But research by British scientists suggests that as little as five minutes of brisk walking can reduce the intensity of nicotine withdrawal symptoms. In the tests, researchers asked participants to rate their need for a cigarette after various types of physical exertion. Those who had exercised reported a reduced desire to smoke. "If we found the same effects in a drug, it would immediately be sold as an aid to help people quit smoking," Adrian Taylor, the study's lead author at the University of Exeter, said last year.

The principle is that exercise can stimulate production of the mood-enhancing hormone dopamine, which can, in turn, reduce smokers' dependence on nicotine. "Dopamine works by replacing or satisfying the need for nicotine," Ratey explains.

Whether the findings will lead office-based smokers to dash out for a jog remains to be seen. After all, you wouldn't want to get addicted to exercise.

How Much Do You Need?
You don't have to become a marathon runner to benefit your brain. The mainstay of exercise is simple, brisk walking, Professor Ratey says.

You'll feel the benefit even from a 30-minute walk. "That's what people need to be doing as a minimum, ideally four or five times a week. If you want to do more, then great."

Professor Ratey also recommends interval training -- really pushing yourself hard for between 20 and 30 seconds while running, cycling or swimming, so that you are momentarily exhausted.

Do, say, two minutes of walking, 30 seconds' sprinting, then two minutes of walking again. It doesn't have to be a lot for a long time, but you will really notice the difference. "The side effects on the body aren't bad either -- I lost 10 pounds in no time," Professor Ratey says.

Fellow soldiers in the aging battle meet!

Dr. Ratey presented the Denham Harman, M.D., Ph.D., Lectureship in Biomedical Gerontology Friday to a full house in the Durham Research Center Auditorium.

During the lecture, Dr. Ratey said exercise and constant challenges are beneficial for the mind. Even stress -- if it has a recovery period-- is productive, he said, noting that growth occurs at that time. It is similar, he said, to weight lifting, which challenges muscles and then makes them stronger during recovery. Physical and mental exercise is a challenge to the brain, Dr. Ratey said.    

"Going out for a run is like a little Prozac and Ritalin," he said. "We feel more focused, calm and motivated afterward. The more activity you are doing, the less cognitive decline."