Just 30 minutes of exercise has benefits for the brain

University of Adelaide neuroscientists have discovered that just one session of aerobic exercise is enough to spark positive changes in the brain that could lead to improved memory and coordination of motor skills.

A study conducted by researchers in the University’s Robinson Research Institute has found changes in the brain that were likely to make it more “plastic” after only 30 minutes of vigorous exercise.

The study involved a small group of healthy people aged in their late 20s to early 30s who rode exercise bikes. They were monitored for changes in the brain immediately after the exercise and again 15 minutes later.

"We saw positive changes in the brain straight away, and these improvements were sustained 15 minutes after the exercise had ended," says research leader Associate Professor Michael Ridding.

"Plasticity in the brain is important for learning, memory and motor skill coordination. The more ‘plastic’ the brain becomes, the more it’s able to reorganise itself, modifying the number and strength of connections between nerve cells and different brain areas."

Associate Professor Ridding says past research has shown that regular physical activity can have positive effects on brain function and plasticity, but it was unknown whether a stand-alone session of exercise would also have similar positive effects.

"We now have evidence suggesting that it does," he says. "This exercise-related change in the brain may, in part, explain why physical activity has a positive effect on memory and higher-level functions."

Associate Professor Ridding says there is now mounting evidence that engaging in aerobic exercise positively influences brain function in many ways - at cellular and molecular levels, as well as in the brain’s architecture.

"Although this was a small sample group, it helps us to better understand the overall picture of how exercise influences the brain," he says.

"We know that plasticity is also important for recovery from brain damage, so this opens up potential therapeutic avenues for patients.

"Further research will be required to see what the possible long-term benefits could be for patients as well as healthy people."

Physical exercise in old age can stimulate brain fitness, but effect decreases with advancing age

Physical exercise in old age can improve brain perfusion as well as certain memory skills. This is the finding of Magdeburg neuroscientists who studied men and women aged between 60 and 77. In younger individuals regular training on a treadmill tended to improve cerebral blood flow and visual memory. However, trial participants who were older than 70 years of age tended to show no benefit of exercise. Thus, the study also indicates that the benefits of exercise may be limited by advancing age. Researchers of the German Center for Neurodegenerative Diseases (DZNE), the University of Magdeburg and the Leibniz Institute for Neurobiology have published these results in the current edition of the journal “Molecular Psychiatry”. Scientists at the Karolinska Institute in Stockholm and the Max Planck Institute for Human Development were also involved in the study.

Lift weights, improve your memory

The Georgia Tech research isn’t the first to find that exercise can improve memory. But the study, which was just published in the journal Acta Psychologica, took a few new approaches. While many existing studies have demonstrated that months of aerobic exercises such as running can improve memory, the current study had participants lift weights just once two days before testing them. The Georgia Tech researchers also had participants study events just before the exercise rather than after workout. They did this because of extensive animal research suggesting that the period after learning (or consolidation) is when the arousal or stress caused by exercise is most likely to benefit memory.

The study began with everyone looking at a series of 90 photos on a computer screen. The images were evenly split between positive (i.e. kids on a waterslide), negative (mutilated bodies) and neutral (clocks) pictures. Participants weren’t asked to try and remember the photos. Everyone then sat at a leg extension resistance exercise machine. Half of them extended and contracted each leg at their personal maximum effort 50 times. The control group simply sat in the chair and allowed the machine and the experimenter to move their legs. Throughout the process, each participant’s blood pressure and heart rate were monitored. Every person also contributed saliva samples so the team could detect levels of neurotransmitter markers linked to stress.

The participants returned to the lab 48 hours later and saw a series of 180 pictures – the 90 originals were mixed in with 90 new photos. The control group recalled about 50 percent of the photos from the first session. Those who exercised remembered about 60 percent.

“Our study indicates that people don’t have to dedicate large amounts of time to give their brain a boost,” said Lisa Weinberg, the Georgia Tech graduate student who led the project.

Although the study used weight exercises, Weinberg notes that resistance activities such as squats or knee bends would likely produce the same results. In other words, exercises that don’t require the person to be in good enough to shape to bike, run or participate in prolonged aerobic exercises.

While all participants remembered the positive and negative images better than the neutral images, this pattern was greatest in the exercise participants, who showed the highest physiological responses. The team expected that result, as existing research on memory indicates that people are more likely to remember emotional experiences especially after acute (short-term) stress.

But why does it work? Existing, non-Georgia Tech human research has linked memory enhancements to acute stress responses, usually from psychological stressors such as public speaking. Other studies have also tied specific hormonal and norepinephrine releases in rodent brains to better memory. Interestingly, the current study found that exercise participants had increased saliva measures of alpha amylase, a marker of central norepinephrine.

“Even without doing expensive fMRI scans, our results give us an idea of what areas of the brain might be supporting these exercise-induced memory benefits,” said Audrey Duarte, an associate professor in the School of Psychology. “The findings are encouraging because they are consistent with rodent literature that pinpoints exactly the parts of the brain that play a role in stress-induced memory benefits caused by exercise.”

The collaborative team of psychology and applied physiology faculty and students plans to expand the study in the future, now that the researchers know resistance exercise can enhance episodic memory in healthy young adults.

“We can now try to determine its applicability to other types of memories and the optimal type and amount of resistance exercise in various populations,” said Minoru Shinohara, an associate professor in the School of Applied Physiology. “This includes older adults and individuals with memory impairment.”

How physical exercise protects the brain from stress-induced depression

Physical exercise has many beneficial effects on human health, including the protection from stress-induced depression. However, until now the mechanisms that mediate this protective effect have been unknown. In a new study in mice, researchers at Karolinska Institutet in Sweden show that exercise training induces changes in skeletal muscle that can purge the blood of a substance that accumulates during stress, and is harmful to the brain. The study is being published in the prestigious journal Cell.

“In neurobiological terms, we actually still don’t know what depression is. Our study represents another piece in the puzzle, since we provide an explanation for the protective biochemical changes induced by physical exercise that prevent the brain from being damaged during stress,” says Mia Lindskog, researcher at the Department of Neuroscience at Karolinska Institutet.

It was known that the protein PGC-1a1 (pronounced PGC-1alpha1) increases in skeletal muscle with exercise, and mediates the beneficial muscle conditioning in connection with physical activity. In this study researchers used a genetically modified mouse with high levels of PGC-1a1 in skeletal muscle that shows many characteristics of well-trained muscles (even without exercising).

These mice, and normal control mice, were exposed to a stressful environment, such as loud noises, flashing lights and reversed circadian rhythm at irregular intervals. After five weeks of mild stress, normal mice had developed depressive behaviour, whereas the genetically modified mice (with well-trained muscle characteristics) had no depressive symptoms.

“Our initial research hypothesis was that trained muscle would produce a substance with beneficial effects on the brain. We actually found the opposite: well-trained muscle produces an enzyme that purges the body of harmful substances. So in this context the muscle’s function is reminiscent of that of the kidney or the liver,” says Jorge Ruas, principal investigator at the Department of Physiology and Pharmacology, Karolinska Institutet.

The researchers discovered that mice with higher levels of PGC-1a1 in muscle also had higher levels of enzymes called KAT. KATs convert a substance formed during stress (kynurenine) into kynurenic acid, a substance that is not able to pass from the blood to the brain. The exact function of kynurenine is not known, but high levels of kynurenine can be measured in patients with mental illness. In this study, the researchers demonstrated that when normal mice were given kynurenine, they displayed depressive behaviour, while mice with increased levels of PGC-1a1 in muscle were not affected. In fact, these animals never show elevated kynurenine levels in their blood since the KAT enzymes in their well-trained muscles quickly convert it to kynurenic acid, resulting in a protective mechanism.

“It’s possible that this work opens up a new pharmacological principle in the treatment of depression, where attempts could be made to influence skeletal muscle function instead of targeting the brain directly. Skeletal muscle appears to have a detoxification effect that, when activated, can protect the brain from insults and related mental illness,” says Jorge Ruas.

Depression is a common psychiatric disorder worldwide. The World Health Organization (WHO) estimates that more than 350 million people are affected.

Study links physical activity in older adults to brain white-matter integrity

Like everything else in the body, the white-matter fibers that allow communication between brain regions also decline with age. In a new study, researchers found a strong association between the structural integrity of these white-matter tracts and an older person’s level of daily activity – not just the degree to which he or she engaged in moderate or vigorous exercise, but also whether the person was sedentary the rest of the time.

The study, reported in the journal PLOS ONE, tracked physical activity in 88 healthy but “low-fit” participants aged 60 to 78. The participants agreed to wear accelerometers during most of their waking hours over the course of a week, and also submitted to brain imaging.

“To our knowledge, this is the first study of its kind that uses an objective measure of physical activity along with multiple measures of brain structure,” said University of Illinois postdoctoral researcher Agnieszka Burzynska, who conducted the research with U. of I. Beckman Institute director Arthur Kramer and kinesiology and community health professor Edward McAuley.

Most studies ask subjects to describe how much physical activity they get, which is subjective and imprecise, Burzynska said. The accelerometer continuously tracks a person’s movement, “so it’s not what they say they do or what they think they do, but we have measured what they are actually doing,” she said.

The researchers assumed that participants’ activity levels over a week accurately reflected their overall engagement, or lack of engagement, in physical activity.

The study also relied on two types of brain imaging. The first, diffusion tensor imaging, offers insight into the structural integrity of a tissue by revealing how water is diffused in the tissue. The second method looks for age-related changes in white matter, called lesions. Roughly 95 percent of adults aged 65 and older have such lesions, Burzynska said. While they are a normal part of aging, their early onset or rapid accumulation may spell trouble, she said.

The team found that the brains of older adults who regularly engaged in moderate-to-vigorous exercise generally “showed less of the white-matter lesions,” Burzynska said.

The association between physical activity and white-matter structural integrity was region-specific, the researchers reported. Older adults who engaged more often in light physical activity had greater structural integrity in the white-matter tracts of the temporal lobes, which lie behind the ears and play a key role in memory, language, and the processing of visual and auditory information.

In contrast, those who spent more time sitting had lower structural integrity in the white-matter tracts connecting the hippocampus, “a structure crucial for learning and memory,” Burzynska said.

“This relationship between the integrity of tracts connecting the hippocampus and sedentariness is significant even when we control for age, gender and aerobic fitness,” she said. “It suggests that the physiological effect of sitting too much, even if you still exercise at the end of the day for half an hour, will have a detrimental effect on your brain.”

The findings suggest that engaging in physical activity and avoiding a sedentary lifestyle are both important for brain health in older age, Burzynska said.

“We hope that this will encourage people to take better care of their brains by being more active,” she said.

Brain signals link physical fitness to better language skills in children

Children who are physically fit have faster and more robust neuro-electrical brain responses during reading than their less-fit peers, researchers report.

These differences correspond with better language skills in the children who are more fit, and occur whether they’re reading straightforward sentences or sentences that contain errors of grammar or syntax.

The new findings, reported in the journal Brain and Cognition, do not prove that higher fitness directly influences the changes seen in the electrical activity of the brain, the researchers say, but offer a potential mechanism to explain why fitness correlates so closely with better cognitive performance on a variety of tasks.

“All we know is there is something different about higher and lower fit kids,” said University of Illinois kinesiology and community health professor Charles Hillman who led the research with graduate student Mark Scudder and psychology professor Kara Federmeier. “Now whether that difference is caused by fitness or maybe some third variable that (affects) both fitness and language processing, we don’t know yet.”

The researchers used electroencephalography (EEG), placing an electrode cap on the scalp to capture some of the electrical impulses associated with brain activity. The squiggly readouts from the electrodes look like seismic readings captured during an earthquake, and characteristic wave patterns are associated with different tasks.

These patterns are called “event-related potentials” (ERPs), and vary according to the person being evaluated and the nature of the stimulus, Scudder said.

For example, if you hear or read a word in a sentence that makes sense (“You wear shoes on your feet”), the component of the brain waveform known as the N400 is less pronounced than if you read a sentence in which the word no longer makes sense (“At school we sing shoes and dance,” for example), Scudder said.

“We focused on the N400 because it is associated with the processing of the meaning of a word,” he said. “And then we also looked at another ERP, the P600, which is associated with the grammatical rules of a sentence.” Federmeier, a study co-author, is an expert in the neurobiological basis of language. Her work inspired the new analysis.

The researchers found that children who were more fit (as measured by oxygen uptake during exercise) had higher amplitude N400 and P600 waves than their less-fit peers when reading normal or nonsensical sentences. The N400 also had shorter latency in children who were more fit, suggesting that they processed the same information more quickly than their peers.

Most importantly, the researchers said, these differences in brain activity corresponded to better reading performance and language comprehension in the children who were more fit.

“Previous reports have shown that greater N400 amplitude is seen in higher-ability readers,” Scudder said.

“Our study shows that the brain function of higher fit kids is different, in the sense that they appear to be able to better allocate resources in the brain towards aspects of cognition that support reading comprehension,” Hillman said.

More work must be done to tease out the causes of improved cognition in kids who are more fit, Hillman said, but the new findings add to a growing body of research that finds strong links between fitness and healthy brain function.

Many studies conducted in the last decade, on children and older adults, ”have repeatedly demonstrated an effect of increases in either physical activity in one’s lifestyle or improvements in aerobic fitness, and the implications of those health behaviors for brain structure, brain function and cognitive performance,” Hillman said.

What Our Ancestors Can Teach Us About Exercise, Alzheimer’s and Human Longevity

Our ancient ancestors’ exercise routines could provide important clues about how best to prevent and treat Alzheimer’s disease and other modern age-related diseases, according to a new paper by two University of Arizona researchers.

The article, featured on the cover of the May issue of the journal Trends in Neurosciences, explores the evolutionary links between physical activity, brain aging and the lifespan of humans, who outlive all other primates.

"This is an effort to try to understand the relationship between exercise and an important genetic risk factor for Alzheimer’s disease and vascular disease, and how the human lifespan evolved, which is a fundamental question that’s been considered in the scientific literature for many years," said UA psychology professor Gene Alexander, who co-authored the paper with David Raichlen, a UA associate professor of anthropology.

While many studies today tout the health benefits of exercise, Alexander and Raichlen consider the link between physical activity and health from an evolutionary perspective, beginning about 2 million years ago. It was around that time that humans made the shift from a more apelike, sedentary lifestyle to a highly active hunter-gatherer lifestyle and began living longer.

During that period, humans likely carried two copies of a genotype known as ApoE4, which is directly linked to higher risk for Alzheimer’s disease and cardiovascular disease. Yet, despite the presence of the problematic gene variation, longer lifespans began to evolve.

"Having this risk allele (ApoE4) is our ancestral condition," Raichlen said. "The lower risk alleles evolved relatively recently, so our question was: How do you evolve a long lifespan when you have this ApoE4 risk allele?"

The answer, Raichlen and Alexander believe, lies in humans’ high level of physical activity 2 million years ago.

"To engage in this hunter-gatherer lifestyle you have to be an aerobically active organism. There’s no way around it. You have to go long distances to find your food," Raichlen said.

"We developed a hypothesis that suggests that exercise may be an important modulating factor that helps to compensate for the negative impact of the (genetic) risk factor for Alzheimer’s and vascular disease, and ultimately might help us to understand why humans are able to live much longer than other primate species," said Alexander, who also teaches in the UA Graduate Interdisciplinary Programs in Neuroscience and Physiological Sciences.

As the human lifestyle today has become increasingly sedentary, this evolutionary link may be important in the development of new prevention therapies and treatments for Alzheimer’s and other age-related diseases, Alexander said.

"We are fundamentally endurance athletes, based on our ancestry. Our recent change, to a more sedentary lifestyle, may have led to a situation where this (ApoE4) genotype has become a problem for us, where it might not have been before," he said.

"With our current tendencies towards less active lifestyles, we need to be thinking about exercise as a potentially important intervention. Considering the evolutionary significance of ApoE4 also gives us some clues about why exercise might be especially important for us."

Today, it has been estimated that about 25 percent of the general U.S. population carries the ApoE4 genotype, and only about 2 percent have two copies of it, putting them at even greater risk for Alzheimer’s or vascular disease. However, the prevalence of the genotype in subgroups of the U.S. population and in some other parts of the world is much higher. 

"There are parts of equatorial Africa where the frequency of the ApoE4 allele is something like 40 percent of the population," Raichlen said, "so thinking about how to use exercise to alter risk around the world is important."

Raichlen has studied in-depth the evolution and effects of physical activity in humans. His research covers a range of topics, including the effects of exercise on happiness, the link between aerobic activity and brain size, the walking patterns of human hunter-gatherers and the role of the runners’ high in human evolution.

Alexander, a member of the UA’s Evelyn F. McKnight Brain Institute and the Arizona Alzheimer’s Consortium, has done extensive research on aging and age-related diseases.

The two came together to explore the connection between their two areas of study by considering research literature in anthropology, brain imaging and neuroscience.

"We’ve generated a new hypothesis from these different scientific literatures that typically don’t cross over," Alexander said. "We are drawing on these different disciplines to look at this question in a new way, and I think it really has important implications for how we understand health issues today. Using what we know about ancestral genotypes, their risks, and how our behaviors evolved over time may help us to gain a better understanding of the underlying mechanisms of Alzheimer’s and age-related cognitive decline."

How Inactivity Changes the Brain

A number of studies have shown that exercise can remodel the brain by prompting the creation of new brain cells and inducing other changes. Now it appears that inactivity, too, can remodel the brain, according to a notable new report.

The study, which was conducted in rats but likely has implications for people too, the researchers say, found that being sedentary changes the shape of certain neurons in ways that significantly affect not just the brain but the heart as well. The findings may help to explain, in part, why a sedentary lifestyle is so bad for us.

Until about 20 years ago, most scientists believed that the brain’s structure was fixed by adulthood, that you couldn’t create new brain cells, alter the shape of those that existed or in any other way change your mind physically after adolescence.

But in the years since, neurological studies have established that the brain retains plasticity, or the capacity to be reshaped, throughout our lifetimes. Exercise appears to be particularly adept at remodeling the brain, studies showed.

But little has been known about whether inactivity likewise alters the structure of the brain and, if so, what the consequences might be.

So for a study recently published in The Journal of Comparative Neurology, scientists at Wayne State University School of Medicine and other institutions gathered a dozen rats. They settled half of them in cages with running wheels and let the animals run at will. Rats like running, and these animals were soon covering about three miles a day on their wheels.

The other rats were housed in cages without wheels and remained sedentary.

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Study examines change in cognitive function following physical, mental activity in older adults

A randomized controlled trial finds that 12 weeks of physical plus mental activity in inactive older adults with cognitive complaints was associated with significant improvement in cognitive function but there was no difference between intervention and control groups, according to a report published Online First by JAMA Internal Medicine, a JAMA Network publication.

An epidemic of dementia worldwide is anticipated during the next 40 years because of longer life expectancies and demographic changes. Behavioral interventions are a potential strategy to prevent or delay dementia in asymptomatic individuals, but few randomized controlled trials have studied the effects of physical and mental activity together, according to the study background.

"We found that cognitive scores improved significantly over the course of 12 weeks, but there were no significant differences between the intervention and active control groups. These results may suggest that in this study population, the amount of activity is more important than the type of activity, because all groups participated in both mental activity and exercise for [60 minutes/per day, three days/per week] for 12 weeks. Alternatively, the cognitive improvements observed may be due to practice effects," the authors note.

The study by Deborah E. Barnes, Ph.D., M.P.H., of the University of California, San Francisco, and colleagues included 126 inactive, community-dwelling older adults with cognitive complaints. All the individuals engaged in home-based mental activity (1 hour/per day, 3 days/per week) plus class-based physical activity (1 hour/per day, 3 days/per week) for 12 weeks and were assigned to either mental activity intervention (MA-I, intensive computer work); or mental activity control (MA-C, educational DVDs) plus exercise intervention (EX-1, aerobic) or exercise control (EX-C, stretching and toning). The study design meant there were four groups: MA-I/EX-I, MA-I/EX-C, MA-C/EX-1 and MA-C/EX-C.

Global cognitive scores improved significantly over time but did not differ between groups in the comparison between MA-I and MA-C (ignoring exercise), the comparison between EX-I and EX-C (ignoring mental activity), or across all four randomization groups, according to the study results.

"The prevalence of cognitive impairment and dementia are projected to rise dramatically during the next 40 years, and strategies for maintaining cognitive function with age are critically needed. Physical or mental activity alone result in small, domain-specific improvements in cognitive function in older adults; combined interventions may have more global effects," the study concludes.

(Image: Getty Images)