The Athlete's Way

Sweat and the biology of bliss

The Brain Drain of Inactivity

An active lifestyle boosts learning and memory at any age.

Every week new studies come out reconfirming the benefits of physical activity. In this entry I will highlight some recent studies that link regular physical activity to improved learning and memory. Throughout our lives, regular physical activity stimulates the growth of new neurons through a process called neurogenesis. This entry focuses on how the daily lifestyle choices you make improve the architecture of your mind. 

A study published on December 6, 2012 in the Journal of Sports Medicine and Physical Fitness shows that Middle school students who are in the best physical shape outscored their classmates on standardized tests and brought home better report cards. This is the first study linking children's fitness to both improved scores on objective tests and better grades. The results showed the fittest children got the highest test scores and the best grades, regardless of gender or whether they'd yet gone through puberty.

This Michigan State University study is also among the first to examine how academic performance relates to all aspects of physical fitness—including body fat, muscular strength, flexibility and endurance—according to lead researcher Dawn Coe. "We looked at the full range of what's called health-related fitness," said Coe. "Kids aren't really fit if they're doing well in just one of those categories."

The findings suggest that cutting physical education and recess may backfire by undermining students' academic performance and success on the standardized tests that affect school funding and prestige, said co-author James Pivarnik, who advised Coe on the project.

"Look, your fitter kids are the ones who will do better on tests, so that would argue against cutting physical activity from the school day," said Pivarnik, an MSU professor of kinesiology. "That's the exciting thing, is if we can get people to listen and have some impact on public policy.” Making fitness a bigger part of children's lives also sets them up for future success,” Pivarnik added."Fit kids are more likely to be fit adults," he said. "And now we see that fitness is tied to academic achievement. So hopefully the fitness and the success will both follow.”

How does physical activity improve learning and memory?

Until the late 1990s scientists did not believe that we could grow new brain cells. But in 1998, the journal Nature Medicine published a report indicating that neurogenesis (the growth of new brain cells) does indeed occur in humans. As Sharon Begley remarked in her book, Train Your Mind, Change Your Brain, "The discovery overturned generations of conventional wisdom in neuroscience. The human brain is not limited to the neurons it is born with, or even the neurons that fill in after the explosion of brain development in early childhood." Within each of our brains there are neural stem cells which are continually replenished and can regenerate into brain neurons.

The process of neurogenesis is controlled by specific gene codes which triggers the production of a protein called, Brain-Derived Neurotrophic Factor (BDNF). BDNF plays a key role in creating new neurons. The gene that turns on BDNF is activated by a variety of factors, including physical exercise. Lab rats that exercise have been shown to produce far more BDNF in their brains when compared to sedentary animals. And, there is a direct relationship between elevation of BDNF levels in these animals and their ability to learn and remember.

Researchers in a report in the Journal of the American Medical Association, entitled "Effect of Physical Activity in Cognitive Function in Older Adults at Risk for Alzheimer's Disease," found that elderly individuals who engaged in regular physical exercise for a 24-week period had an improvement of an astounding 1,800 percent on measures of memory, language ability, attention and other important cognitive functions compared to an age-matched group not involved in the exercise program.

The mechanism by which exercise enhances brain performance is described in these and other studies as being directly linked with increased production of BDNF.

Neurogenesis in the Hippocampus

Researchers in 2010 found an association between physical fitness levels and the hippocampus size of 9 and 10-year-old children. The children who were more fit had a larger hippocampus and performed better on a test of memory than their less-fit peers. The hippocampus is a structure tucked deep in the brain, which is known to be important in learning and memory.

"This is the first study I know of that has used MRI measures to look at differences in brain between kids who are fit and kids who aren't fit," said University of Illinois psychology professor and Beckman Institute director Art Kramer, who led the study with doctoral student Laura Chaddock and kinesiology and community health professor Charles Hillman. "Beyond that, it relates those measures of brain structure to cognition."

When they analyzed the MRI data, the researchers found that the physically fit children tended to have bigger hippocampal volume — about 12 percent bigger relative to total brain size — than their out-of-shape peers. The children who were in better physical condition also did better on tests of relational memory — the ability to remember and integrate various types of information — than their less-fit peers.

Other studies in older adults and in animals have also shown that exercise can increase the size of the hippocampus. A larger hippocampus is associated with better performance on spatial reasoning and other cognitive tasks. "In animal studies, exercise has been shown to specifically affect the hippocampus, significantly increasing the growth of new neurons and cell survival, enhancing memory and learning, and increasing molecules that are involved in the plasticity of the brain," Chaddock said.

An active lifestyle preserves gray matter and slows Alzheimer's 

According to a study presented on November 26, 2012 an active lifestyle helps preserve gray matter in the brains of older adults and could reduce the burden of dementia and Alzheimer's disease. Alzheimer's disease currently has no cure and is the most common cause of dementia. More than 35 million people worldwide live with dementia, according to the World Health Organization, and the prevalence is expected to double by 2030. 

Cyrus Raji, M.D., Ph.D., radiology resident at the University of California in Los Angeles, and colleagues recently examined how an active lifestyle can influence brain structure in 876 adults, with an average age of 78 years. The patients' conditions ranged from normal cognition to Alzheimer's dementia. "We had 20 years of clinical data on this group, including body mass index and lifestyle habits," Dr. Raji said. "We drew our patients from four sites across the country, and we were able to assess energy output in the form of kilocalories per week."

The lifestyle factors examined included recreational sports, gardening and yard work, bicycling, dancing and riding an exercise cycle. The researchers used magnetic resonance imaging (MRI) and a technique called voxel-based morphometry to model the relationships between energy output and gray matter volume.

Dr. Raji said, "Gray matter volume is a key marker of brain health. Larger gray matter volume means a healthier brain. Shrinking volume is seen in Alzheimer's disease. Gray matter includes neurons that function in cognition and higher order cognitive processes. The areas of the brain that benefited from an active lifestyle are the ones that consume the most energy and are very sensitive to damage."
The researchers found a strong association between energy output and gray matter volumes in areas of the brain crucial for cognitive function.

Greater caloric expenditure was related to larger gray matter volumes in the frontal, temporal and parietal lobes, including the hippocampus, posterior cingulate and basal ganglia. There was a strong association between high energy output and greater gray matter volume in patients with mild cognitive impairment and Alzheimer's disease.

A key aspect of the study was its focus on having a variety in lifestyle choices, Dr. Raji noted. "What struck me most about the study results is that it is not one but a combination of lifestyle choices and activities that benefit the brain," he said. "Virtually all of the physical activities examined in this study are some variation of aerobic physical activity, which we know from other work can improve cerebral blood flow and strengthen neuronal connections," he said. "Additional work needs to be done," Dr. Raji added. "However, our initial results show that brain aging can be alleviated through an active lifestyle."

Conclusion

Homo Sapiens evolved for millenia to be physically active from childhood into our senior years. Our current sedentary lifestyle is causing our collective waist-lines to swell and our brain cells to shrink. Each of us needs to move our bodies a little bit each day to keep our brains healthy and our minds strong. The Greeks had it right: "A Sound Mind in a Sound Body."  I'm much less concerned about the "Body Mass Index" of Americans than the "Brain Mass Index" that is atrophying due to inactivitiy.

People talk a lot about the skyrocketing health care costs linked to unhealthy lifestyle choices and obesity. But what will the trickle down of the 'Brain Drain' caused by inactivity be on American ingenuity, innovation, entrepreneurship, trademarks, patents, etc? How much does our collective lack of physical activity stunt creative thinking and new ideas en masse? How much does inactivity impact our Gross Domestic Product? Can we remain a "Super Power" if our citizens remain sedentary? These are questions Americans from all walks of life should be asking ourselves as we approach the fiscal cliff. 

Regardless of any altruistic motives, business and government leaders need to focus on ways to inspire and facilitate Americans of all generations to stay active throughout their lifetimes. As a nation we are only as strong as our weakest link. Inactivity and obesity could sink the U.S.A. in a global economy. 

 

Christopher Bergland is a world-class endurance athlete, coach, author, and political activist.

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