New biomarkers show exercise helps reduce daytime sleep disorder
August 11, 2015
Science Daily/UT Southwestern Medical Center
Aerobic exercise can help alleviate excessive daytime sleepiness among depressed individuals, researchers have found. Researchers looking at blood samples identified two biological markers for the condition, called hypersomnia, which is characterized by sleeping too much at night as well as excessive daytime sleepiness, in those with Major Depressive Disorder.
Researchers looking at blood samples identified two biological markers for the condition, called hypersomnia, which is characterized by sleeping too much at night as well as excessive daytime sleepiness, in those with Major Depressive Disorder. Exercise reduced the levels of the two biomarker proteins, resulting in reduced excessive sleepiness, the researchers found.
"Hypersomnia, as well as insomnia, have been linked in the development, treatment, and recurrence of depression. Sleep disturbances are also some of the most persistent symptoms in depression. Identifying these biomarkers, combined with new understanding of the important role of exercise in reducing hypersomnia, have potential implications in the treatment of major depressive disorder," said senior author Dr. Madhukar Trivedi, Director of UT Southwestern's Center for Depression Research and Clinical Care, and Chief of the Mood Disorders Division of Psychiatry at UT Southwestern.
People with hypersomnia are compelled to nap repeatedly during the day, often at inappropriate times such as at work, during a meal, or in conversation. They often have difficulty waking from a long sleep, and may feel disoriented upon waking, according to the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health (NIH). Other symptoms may include anxiety, increased irritation, decreased energy, restlessness, slow thinking, slow speech, loss of appetite, hallucinations, and memory difficulty. Some patients lose the ability to function in family, social, occupational, or other settings.
Researchers had previously found a negative loop in which sleep, inflammation and depression interact and progressively worsen. The results of the current and previous research on insomnia suggest that exercise may be resetting this negative feedback loop, said Dr. Trivedi, who holds the Betty Jo Hay Distinguished Chair in Mental Health, and received the 2015 American Psychiatric Association Award for Research, the Association's most significant award for research.
The researchers were able to identify the biomarkers based on blood samples provided by participants in the Treatment with Exercise Augmentation for Depression (TREAD) study, who were randomly assigned to two types of aerobic exercise to determine the effects of exercise on their depression. More than 100 subjects ages 18 to 70 who had Major Depression Disorder participated, and as part of the study had also agreed to provide blood samples.
In this study, researchers examined four biomarkers − brain-derived neurotrophic factor (BDNF) and inflammatory cytokines called tumor necrosis factor alpha, and two interleukins, IL-1β and IL-6, from blood samples collected before and after the 12-week exercise intervention.
Researchers found that reductions in two biomarkers, BDNF and IL-1β, are related to reductions in hypersomnia. "Identification of biomarkers that uniquely predict or correlate with improvements in hypersomnia and insomnia is an important step toward more effective treatment of MDD," said lead author Dr. Chad Rethorst, Assistant Professor of Psychiatry with the Center for Depression Research and Clinical Care.
Previous analysis of the TREAD data demonstrated significant reductions in insomnia symptoms with exercise, but the two biomarkers identified above did not correlate to changes in insomnia, Dr. Rethorst said. They did find, however, that lower baseline levels of IL-1β were predictive of greater improvements in insomnia. The findings suggest distinct mechanisms are involved in insomnia versus hypersomnia, and that further research will be needed to identify the appropriate biomarkers for insomnia.
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/08/150811160431.htm
Cardiorespiratory fitness linked to thinner gray matter and better math skills in kids
August 12, 2015
Science Daily/University of Illinois at Urbana-Champaign
A new study reveals that 9- and 10-year-old children who are aerobically fit tend to have significantly thinner gray matter and do better on math tests than their 'lower-fit' peers.
The study suggests, but does not prove, that cardiorespiratory fitness contributes to gray matter thinning -- a normal process of child brain development. The study also offers the first evidence that fitness enhances math skills by aiding the development of brain structures that contribute to mathematics achievement.
"Gray-matter loss during child development is part of healthy maturation," said University of Illinois postdoctoral researcher Laura Chaddock-Heyman, who led the research with U. of I. Beckman Institute for Science and Technology director Art Kramer and kinesiology and community health professor Charles Hillman. "Gray-matter thinning is the sculpting of a fully formed, healthy brain. The theory is that the brain is pruning away unnecessary connections and strengthening useful connections."
Previous studies have shown that gray-matter thinning is associated with better reasoning and thinking skills, Chaddock-Heyman said.
"We show, for the first time, that aerobic fitness may play a role in this cortical thinning," she said. "In particular, we find that higher-fit 9- and 10-year-olds show a decrease in gray-matter thickness in some areas known to change with development, specifically in the frontal, temporal and occipital lobes of the brain."
The analysis included 48 children, all of whom had completed a maximal oxygen-uptake fitness test on a treadmill. Half of the children (the higher-fit kids) were at or above the 70th percentile for aerobic fitness, and half (the lower-fit kids) were at or below the 30th percentile. The researchers imaged the children's brains using MRI, and tested their math, reading and spelling skills using the Wide Range Achievement Test-3, which correlates closely with academic achievement in these fields.
The team found differences in math skills and cortical brain structure between the higher-fit and lower-fit children. In particular, thinner gray matter corresponded to better math performance in the higher-fit kids. No significant fitness-associated differences in reading or spelling aptitude were detected.
"These findings arrive at an important time. Physical activity opportunities during the school day are being reduced or eliminated in response to mandates for increased academic time," Hillman said. "Given that rates of physical inactivity are rising, there is an increased need to promote physical activity. Schools are the best institutions to implement such health behavior practices, due to the number of children they reach on a daily basis."
"An important next step in this research is to establish a causal relationship between brain changes, changes in physical fitness and changes in cognition and school achievement -- something we are currently doing with a longitudinal study of children participating in a physical activity training program," Kramer said.
The National Institute on Aging, the National Institute of Child Health and Human Development, and the National Institute of Diabetes and Digestive and Kidney Diseases at the National Institutes of Health supported this research. The National Institute of Food and Agriculture at the U.S. Department of Agriculture also provided funding.
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/08/150812151229.htm
Higher intelligence score means better physical performance
August 14, 2015
Science Daily/University of Copenhagen The Faculty of Health and Medical Sciences
New research reveals a distinct association between male intelligence in early adulthood and their subsequent midlife physical performance. The higher intelligence score, the better physical performance, the study reveals.
We would all like to stay independent, as we get older. In order to succeed, we need to be in good physical shape. This includes being able to cope with everyday physical activities such as getting dressed and carrying our own shopping. Scientists employ a number of tests, e.g. handgrip strength, balance and chair-rise, when measuring physical performance.
Researchers at the Center for Healthy Aging and the Department of Public Health at the University of Copenhagen have studied the association between male intelligence in early adulthood and their subsequent physical performance, aged 48-56. The study comprised 2,848 Danish males born in 1953 and in 1959-61, and the results have just been published in the scientific Journal of Aging and Health.
Avoiding decrease in physical performance in old age
"Our study clearly shows that the higher intelligence score in early adulthood, the stronger the participants' back, legs and hands are in midlife. Their balance is also better. Former studies have taught us that the better the results of these midlife tests, the greater the chance of avoiding a decrease in physical performance in old age," says PhD student Rikke Hodal Meincke from the Center for Healthy Aging and the Department of Public Health.
With a 10-point increase in intelligence score, the results revealed a 0,5 kg increase in lower back force, 1 cm increase in jumping height -- an expression of leg muscle power, 0.7 kg increase in hand-grip strength, 3.7% improved balance, and 1.1 more chair-rises in 30 seconds.
Easier to stay physically active throughout life
"A feasible explanation for this connection between male intelligence in early adulthood and their midlife physical performance could be that people with a higher intelligence score find it easier to understand and interpret health information and thus have a healthier lifestyle, they may, for instance, exercise more regularly. Exercise can thus be viewed as a mechanism that explains the connection between intelligence and physical performance," Rikke Hodal Meincke elaborates.
She believes that the study's results are important for the future planning and targeting of initiatives that may help improve or maintain elderly peoples' physical performance. By way of example, this could include making it easier for everybody, regardless of abilities, to remain physically active throughout their lives. She does, however, stress that more studies are needed, in order to examine mechanisms that reveal exactly where to set in.
Previous research has shown that exercise, health status and socio-economics influence physical performance. Furthermore, childhood factors may also influence physical performance in later life.
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/08/150814101523.htm
Why does running make us happy?
September 1, 2015
Science Daily/University of Montreal
The joy of running. That sense of well-being, freedom and extra energy that runners often experience is not just a matter of endorphins. A new study shows that the "runner's high" phenomenon is also caused by dopamine, an important neurotransmitter for motivation.
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A new study shows that the "runner's high" phenomenon is also caused by dopamine, an important neurotransmitter for motivation.
Credit: © Martinan / Fotoli
"We discovered that the rewarding effects of endurance activity are modulated by leptin, a key hormone in metabolism. Leptin inhibits physical activity through dopamine neurons in the brain," said Stephanie Fulton, a researcher at the CRCHUM and lead author of an article published in the journal Cell Metabolism.
Secreted by adipose tissue, leptin helps control the feeling of satiety. This hormone also influences physical activity. "The more fat there is, the more leptin there is and and the less we feel like eating. Our findings now show that this hormone also plays a vital role in motivation to run, which may be related to searching for food," explained Stephanie Fulton, who is also a professor at Université de Montréal's Department of Nutrition.
Hormone signals that modulate feeding and exercise are in fact believed to be closely linked. Endurance running capacity in mammals, particularly humans, is thought to have evolved to maximize the chances of finding food. This study suggests that leptin plays a critical role both in regulating energy balance and encouraging behaviours that are "rewarding" for the person's metabolism, i.e., engaging in physical activity to find food.
The researchers studied voluntary wheel running in mice in cages. These mice can run up to seven kilometres a day. In a laboratory, the physical activity of normal mice was compared with that of mice who underwent a genetic modification to suppress a molecule activated by leptin, STAT3 (signal transducer and activator of transcription-3). The STAT3 molecule is found in the neurons that synthesize dopamine in the midbrain. This "mesolimbic dopaminergic pathway" is a like a motivational highway in the brain.
"Mice that do not have the STAT3 molecule in the dopaminergic neurons run substantially more. Conversely, normal mice are less active because leptin then activates STAT3 in the dopamine neurons, signalling that energy reserves in the body are sufficient and that there is no need to get active and go looking for food," explained Maria Fernanda Fernandes, first author of the study.
And is leptin as important for motivation to be active in humans? Yes. "Previous studies have clearly shown a correlation between leptin and marathon run times. The lower leptin levels are, the better the performance. Our study on mice suggests that this molecule is also involved in the rewarding effects experienced when we do physical exercise. We speculate that for humans, low leptin levels increase motivation to exercise and make it easier to get a runner's high," summed up Stephanie Fulton.
Mice, humans and mammals in general are thought to have evolved to increase the return on effective food acquisition behaviours. Ultimately, hormones are sending the brain a clear message: when food is scarce, it's fun to run to chase some down.
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/08/150831085456.htm
Types of athletic training affect how brain communicates with muscles
September 18, 2015
Science Daily/University of Kansas
The brains of endurance trainers communicate with muscles differently than those of strength trainers or sedentary individuals, new research shows. While it is not immediately clear why the communication between the brain and muscle was different as a result of different types of exercise, one researcher said it offers leads for new means of research into neuromechanical differences in muscle function, muscle performance, muscle stiffness and other areas.
Using endurance training or strength and resistance training not only prepares an athlete for different types of sports, they can also change the way the brain and muscles communicate with each other.
A University of Kansas study shows that the communication between the brain and quadriceps muscles of people who take part in endurance training, such as running long distances, is different than those who regularly took part in resistance training and those who were sedentary. The findings may offer clues to the type of physical activity humans are most naturally suited to.
Trent Herda, assistant professor of health, sport and exercise sciences, and Michael Trevino, a doctoral student, conducted studies in which they measured muscle responses of five people who regularly run long distances, five who regularly lift weights and five sedentary individuals who regularly do neither. The studies have been published in the Journal of Sports Sciences and Muscle and Nerve.
Among the findings, Herda and Trevino showed that the quadriceps muscle fibers of the endurance trainers were able to fire more rapidly.
"The communication between the brains and their muscles was slightly different than the resistance trainers and sedentary individuals," Herda said of endurance trainers. "This information also suggested that resistance trainers and those who are sedentary were more likely to fatigue sooner, among other things."
Survey participants were 15 healthy volunteers. The endurance trainers had consistently taken part in a structured running program for at least three years prior to the study and ran an average of 61 miles a week and did not take part in resistance training. The resistance trainers had consistently taken part in a weight-training program for at least four years prior to the study. They took part in resistance training four to eight hours per week and reported doing at least one repetition of a back squat of twice their body mass. One reported doing a squat of 1.5 times his or her body weight, but none engaged in aerobic activity such as swimming, jogging or cycling. The sedentary participants did not take part in any structured physical exercise for three years prior to the study.
Participants wore mechanomyographic and electromyographic electrode sensors on their quadriceps muscle and extended their leg while seated. The researchers measured submaximal contraction and total force by having participants extend their leg, then exert more force, attempting to achieve from 40 to 70 percent of total force, which they could see represented in real time on a computer screen.
While it is not immediately clear why the communication between the brain and muscle was different as a result of different types of exercise as evidenced by the difference in rates of muscle fibers firing, Herda said it offers leads for new means of research into neuromechanical differences in muscle function, muscle performance, muscle stiffness and other areas. It also provides several clues into the type of exercise humans are more naturally built for. While not claiming that one type of exercise or sport is superior to another, Herda said the findings suggest that the human body's neuromuscular system may be more naturally inclined to adapt to aerobic exercise than resistance training for strength as the communication between the brain and muscles was similar between resistance training and sedentary individuals.
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/09/150918132022.htm
The link between imagery and performance
December 23, 2015
Science Daily/New Mexico State University (NMSU)
Imagine standing on a basketball court, throwing the basketball and watching it arc into the net. Chances are you’ll make that shot without a problem if you’ve been practicing, according to new research.
https://images.sciencedaily.com/2015/12/151223165503_1_540x360.jpg
Former NMSU soccer player Katelyn Smith participates in an anticipation timing study in professor Phillip Post’s laboratory. Post is exploring the link between athletic performance and imagery in hopes of using his research in clinical settings.
Credit: NMSU photo by Adriana M. Chavez
Chances are you'll make that shot without a problem if you've been practicing on the court regularly, according to research by Phillip Post, associate professor in the Kinesiology and Dance Department in the College of Education at New Mexico State University. Post is studying the link between imagery and how it impacts motor learning and sport performance. Recently, Post presented his research at an international conference at Universidad Autónoma de Chihuahua.
"Specifically, I presented research, mostly research that I conducted, on the efficacy of using imagery to enhance learning or motor performance of well-rehearsed tasks," Post said. "The research presented suggests that imagery might be effective for enhancing learner's skill acquisition of tasks that contain greater cognitive elements, such as tasks that require decision making or remembering a sequence or pattern, as opposed to motor elements, or tasks that require correct skill execution, like a soccer kick. However, with more experienced performers imagery appears to be effective on a range of tasks, including both motor and cognitive. In addition to this research I discussed imagery theories and how to best apply the mental skill."
At his lab on campus, Post is exploring two different lines of research. One looks at the application of imagery, particularly looking at allowing learners to acquire new skills and seeing how mentally rehearsing a particular sports skill or motor task affects their skill acquisition of it. The other looks at how imagery enhances the performance of well-rehearsed skills.
"We look at that in terms of the mental strategy of learning and also in terms of sport performance. We also do some basic motor learning types of experiments in here to see what practice conditions facilitate skill acquisition," Post said. "We want to apply these not only to instructional settings but also to rehab settings, where practitioners need to design practice protocols that are going to facilitate their patients' skill acquisition skills or help them relearn skills."
As part of his research, Post uses an anticipation timing device where participants use a ping pong paddle to time their swing as a line of light bulbs turn on, mimicking the path of a ping pong ball.
"When you try to catch a baseball or an object, you have to be able to time it so that when the object arrives to you, you have your hands up with the arrival of that particular ball or object," Post said. "It's pretty prominent with a lot of daily skills, things such as driving or sports. We want to be on target so that we are arriving at the location of where that ball or that object is going to be."
Post said the device allows him to measure to the millisecond how good participants are at timing their responses. He uses three groups to conduct his research: a group that physically practices their timing, a group that images their timing and a "combo" group that prepares both physically and mentally. He also uses a control group.
"With this apparatus, we want to know can learners improve their ability to intercept a light upon its arrival at a target location," Post said. "How does mentally rehearsing affect a participant's ability to learn this particular task?"
Ray Delgado, an NMSU kinesiology major and Post's undergraduate research assistant, said he became interested in the research after playing college baseball for three years.
"I was taking sports psychology with Dr. Post and he talked about the different things we've worked on in here. It really sparked my interest," said Delgado, who plans to pursue a doctoral degree in physical therapy. "In the long run, this helps me see how I can apply some of these strategies in therapy to see how we can use imagery in therapy and assist the rehab process."
Post said he hopes that in the near future, his research will help patients who have suffered a stroke or have been diagnosed with diseases such as Parkinson's.
"We hope to run interventions or studies to help the various clinical populations reacquire tasks faster and reduce their physical therapy time," Post said.
Robert Wood, the interim associate dean of research for the College of Education, said he's impressed with Post's work.
"The imagery work has many important applications, including human performance and rehabilitation," Wood said. "I am very excited about Dr. Post's work, not only because of the relevance to contemporary issues, but also because of the high quality of the work. We are quite fortunate to have him."
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/12/151223165503.htm
Early-life exercise alters gut microbes, promotes healthy brain and metabolism
December 29, 2015
Science Daily/University of Colorado at Boulder
The human gut harbors a teeming menagerie of over 100 trillion microorganisms, and researchers have discovered that exercising early in life can alter that microbial community for the better, promoting healthier brain and metabolic activity over the course of a lifetime.
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This is a picture of microbes under a microscope.
Credit: Photo by NIAID
The research, which was recently published in the journal Immunology and Cell Biology, indicates that there may be a window of opportunity during early human development to optimize the chances of better lifelong health.
"Exercise affects many aspects of health, both metabolic and mental, and people are only now starting to look at the plasticity of these gut microbes," said Monika Fleshner, a professor in CU-Boulder's Department of Integrative Physiology and the senior author of the new study. "That is one of the novel aspects of this research."
Microbes take up residence within human intestines shortly after birth and are vital to the development of the immune system and various neural functions. These microbes can add as many 5 million genes to a person's overall genetic profile and thus have tremendous power to influence aspects of human physiology.
While this diverse microbial community remains somewhat malleable throughout adult life and can be influenced by environmental factors such as diet and sleep patterns, the researchers found that gut microorganisms are especially 'plastic' at a young age.
The study found that juvenile rats who voluntarily exercised every day developed a more beneficial microbial structure, including the expansion of probiotic bacterial species in their gut compared to both their sedentary counterparts and adult rats, even when the adult rats exercised as well.
The researchers have not, as of yet, pinpointed an exact age range when the gut microbe community is likeliest to change, but the preliminary findings indicate that earlier is better.
A robust, healthy community of gut microbes also appears to promote healthy brain function and provide anti-depressant effects, Fleshner said. Previous research has shown that the human brain responds to microbial signals from the gut, though the exact communication methods are still under investigation.
"Future research on this microbial ecosystem will hone in on how these microbes influence brain function in a long-lasting way," said Agniezka Mika, a graduate researcher in CU-Boulder's Department of Integrative Physiology and the lead author of the new study.
Going forward, the researchers also plan to explore novel means of encouraging positive gut microbe plasticity in adults, who tend to have stable microbial communities that are more resistant to change.
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/12/151229204252.htm
Exercise reduces suicide attempts by 23 percent among bullied teens
September 21, 2015
Science Daily/University of Vermont
As high schools across the country continue to reduce physical education, recess, and athletic programs, a new study shows that regular exercise significantly reduces both suicidal thoughts and attempts among students who are bullied.
Using data from the CDC's National Youth Risk Behavior Survey of 13,583 high school students, researchers at the University of Vermont found that being physically active four or more days per week resulted in a 23 percent reduction in suicidal ideation and attempts in bullied students. Nationwide nearly 20 percent of students reported being bullied on school property.
Previous studies have shown that exercise has positive effects on various mental health measures. This is the first, however, to show a link between physical activity and a reduction in suicidal thoughts and attempts by bullied students, who are also at increased risk for poor academic performance, low self-esteem, anxiety, depression, sadness and substance abuse.
Overall, 30 percent of students in the study reported feeling sad for two or more weeks in the previous year while more than 22 percent reported suicidal ideation and 8.2 percent reported actual suicidal attempts during the same time period. Bullied students were twice as likely to report sadness, and three times as likely to report suicidal ideation or attempt when compared to peers who were not bullied. Exercise on four or more days per week was also associated with significant reductions in sadness.
"I was surprised that it was that significant and that positive effects of exercise extended to kids actually trying to harm themselves," said lead author Jeremy Sibold, associate professor and chair of the Department Rehabilitation and Movement Science. "Even if one kid is protected because we got them involved in an after-school activity or in a physical education program it's worth it."
High schools cutting physical edcuation programs nationwide
The release of Sibold's study in the Journal of the American Academy of Child & Adolescent Psychiatry comes at a time when 44 percent of the nation's school administrators have cut significant amounts of time from physical education, arts and recess so that more time could be devoted to reading and mathematics since the passage of No Child Left Behind in 2001, according to a report by the Institute of Medicine of the National Academies. The same report showed that the percentage of schools offering physical education daily or at least three days a week has declined dramatically between 2001 and 2006.
Overall, it is estimated that only about half of America's youth meet the current evidence-based guideline of the U.S. Health and Human Services Department of at least 60 minutes of vigorous or moderate-intensity physical activity daily. In its biennial survey of high school students across the nation, the Center for Disease Control and Prevention reported that nearly half said they had no physical education classes in an average week.
"It's scary and frustrating that exercise isn't more ubiquitous and that we don't encourage it more in schools," says Sibold. "Instead, some kids are put on medication and told 'good luck.' If exercise reduces sadness, suicide ideation, and suicide attempts, then why in the world are we cutting physical education programs and making it harder for students to make athletic teams at such a critical age?"
Sibold and his co-authors, Erika Edwards, research assistant professor in the College of Engineering and Mathematical Sciences, Dianna Murray-Close, associate professor in psychology, and psychiatry professor James J. Hudziak, who has published extensively on the positive effects of exercise on mental health outcomes, say they hope their paper increases the consideration of exercise programs as part of the public health approach to reduce suicidal behavior in all adolescents.
"Considering the often catastrophic and long lasting consequences of bullying in school-aged children, novel, accessible interventions for victims of such conduct are sorely needed," they conclude.
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/09/150921095433.htm
Lack of exercise linked to alcohol misuse
African-Americans who did not engage in physical activity were nearly twice as likely to abuse alcohol
November 2, 2015
Science Daily/Johns Hopkins University Bloomberg School of Public Health
A large-scale survey of African-American men and women found that those who rarely or never exercised had about twice the odds of abusing alcohol than those who exercised frequently, a finding that could have implications across all groups.
The survey of 5,002 African-American men and women found that those who did not engage in physical activity at all or only occasionally had nearly double the chance -- between a 84 percent and 88 percent higher odds -- of abusing alcohol than those who regularly engaged in some form of physical activity. This was after adjusting for demographic factors such as income and neighborhood characteristics.
Survey participants were drawn from the National Survey of American Life (NSAL), a study that took place between 2001 and 2003 and aimed to identify racial and ethnic differences in mental disorders and other psychological distress, including those used by the Diagnostic and Statistical Manual of Mental Disorders. The study used the DSM-IV definition of alcohol abuse, which is defined as drinking that has negative social, professional and/or legal consequences.
The survey finding will be presented at the American Public Health Association meeting in Chicago on Nov. 2.
"There have been studies of the association between substance use and related comorbid health conditions, such as depression and anxiety," notes April Joy Damian, a doctoral student in the Department of Mental Health at the Johns Hopkins Bloomberg School of Public Health and the study's author. "There has been little research that has examined the connection between exercise and decreased odds of alcohol use disorder.
"Because the NSAL study was essentially a snapshot that was taken at one point in time, we can't say that engaging in physical activity will prevent people from developing alcohol use disorder or that alcohol use disorder can be treated with physical activity," Damian says. "Given that alcohol use disorder has a high rate of co-occurrence for depression and anxiety, it merits further study all around, for African Americans as well as others. We should consider how physical activity contributes to alcohol-related behavior and design interventions for people who are at risk."
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/11/151102152548.htm
Faster brain waves make shorter gaps in visual stream
November 10, 2015
Science Daily/University of Wisconsin-Madison
'Blink and you'll miss it' isn't only for eyelids. The human brain also blinks, dropping a few frames of visual information here and there. Those lapses of attention come fast -- maybe just once every tenth of a second. But some people may be missing more than others, according to psychologists.
Those lapses of attention come fast -- maybe just once every tenth of a second. But some people may be missing more than others, according to psychologists at the University of Wisconsin-Madison.
"Intuitively we have this sense that we're viewing the world in a continuous stream, constantly taking in the same amount of information," says Jason Samaha, a UW-Madison doctoral student in psychology. "So if I told people that every 100 milliseconds their brains were taking a bit of a break, I think that would surprise a lot of them."
Samaha and UW-Madison psychology Professor Brad Postle have drawn a connection between that quick blink in the visual processing system and a rhythmic pattern in the brain's electrical activity called the alpha oscillation.
Alpha oscillations are regular fluctuations in the electrical activity in the back of the human brain -- an area that includes the visual cortex, responsible for processing signals from the eyes. These alpha oscillations rise and fall endlessly, tracing a wave-like thrum of brain activity.
Recently, brain researchers demonstrated that our visual acuity is at its best when a visual stimulus appears as the alpha wave is near a certain peak. The farther from that peak, the more likely a flash of visual information falls on the retina without consciously registering on the viewer.
"That made us wonder: Maybe this is a neural marker that can predict the rate at which we sample the world visually," says Samaha, whose work on that marker was published recently in the journal Current Biology. "Someone with a faster alpha oscillation has more of those peaks. It's almost as if they're sampling the world more frequently than someone with a slower alpha oscillation."
To test that idea, Samaha sat people in front of a screen and asked them to watch closely spaced flashes of light. Their alpha oscillations were recorded before and during the task.
"The flashes can be so close together that they appear to be one," Samaha says. "A delay of 10 milliseconds (just one-hundredth of a second), for example, is just too fast for you to perceive two flashes."
The longer the delay between flashes, the more likely the test subjects could correctly discern two flashes from one. But the subjects began to sort themselves out based on alpha frequency.
"People with a faster alpha frequency can perceive two flashes with a significantly shorter gap between them -- maybe 25 milliseconds," says Samaha, "whereas someone with a slower alpha frequency can't perceive two flashes until they have closer to 45 milliseconds delay."
The faster the regular rhythm of the working brain (represented by alpha oscillation), the more fine-grained the resolution in visual perception.
Of course, precious few discrete events take place within a couple dozen milliseconds. Blinking eyelids can take 400 milliseconds -- a relatively pregnant pause -- to close and reopen. But in cases where physical reaction time is at a premium, every bit helps.
Samaha thinks of a baseball player. In the 400 milliseconds it takes a professionally thrown fastball to reach the plate, the batter has to budget time for locating the baseball, identifying its spin, deciding whether and where to swing, and actually whipping the bat around to the right spot.
"In a very brief window of time, you have to choose to begin a reaction and where to direct it," says Samaha. "Having finer resolution may help in cases like that. Maybe good hitters -- and other people who can react quickly to a visual stimulus -- have very fast alpha oscillations."
World Series outcomes aside, Samaha sees the study's results contributing to deeper discussions of how we relate to the world around us.
"The more interesting implications of the research concern what constitutes our conscious visual perception of the world," he says. "We seem to find a neural marker of conscious visual updating, and that's interesting to a lot of people who are looking for neural correlates of consciousness."
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/11/151110171354.htm
How exercise may energize brain cell function
November 19, 2015
Science Daily/Johns Hopkins Medicine
As we age or develop neurodegenerative diseases such as Alzheimer's, our brain cells may not produce sufficient energy to remain fully functional. Researchers have discovered that an enzyme called SIRT3 that is located in mitochondria — the cell's powerhouse — may protect mice brains against the kinds of stresses believed to contribute to energy loss. Furthermore, mice that ran on a wheel increased their levels of this protective enzyme.
Researchers led by Mark Mattson, Ph.D., of the National Institute on Aging Intramural Research Program and Johns Hopkins University School of Medicine, used a new animal model to investigate whether they could aid neurons in resisting the energy-depleting stress caused by neurotoxins and other factors. They found the following:
• Mice models that did not produce SIRT3 became highly sensitive to stress when exposed to neurotoxins that cause neurodegeneration and epileptic seizures.
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* Running wheel exercise increased the amount of SIRT3 in neurons of normal mice and protected them against degeneration; in those lacking the enzyme, running failed to protect the neurons.
* Neurons could be protected against stress through use of a gene therapy technology to increase levels of SIRT3 in neurons.
These findings suggest that bolstering mitochondrial function and stress resistance by increasing SIRT3 levels may offer a promising therapeutic target for protecting against age-related cognitive decline and brain diseases. The research team report their findings online Nov. 19 in the journal Cell Metabolism.
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/11/151119122623.htm
Improving fitness may counteract brain atrophy in older adults
Exercise may help to reverse neurodegeneration in those with mild cognitive impairment, an early stage of Alzheimer's disease
November 19, 2015
Science Daily/University of Maryland
Older adults that improved their fitness through a moderate intensity exercise program increased the thickness of their brain's cortex, the outer layer of the brain that typically atrophies with Alzheimer's disease, according to a new study. These effects were found in both healthy older adults and those diagnosed with mild cognitive impairment, an early stage of Alzheimer's disease.
"Exercise may help to reverse neurodegeneration and the trend of brain shrinkage that we see in those with MCI and Alzheimer's," says Dr. J. Carson Smith, associate professor of kinesiology and senior author of the study, published in the Journal of the International Neuropsychological Society on Nov. 19, 2015. "Many people think it is too late to intervene with exercise once a person shows symptoms of memory loss, but our data suggest that exercise may have a benefit in this early stage of cognitive decline."
The previously physically inactive participants (ages 61-88) were put on an exercise regimen that included moderate intensity walking on a treadmill four times a week over a twelve-week period. On average, cardiorespiratory fitness improved by about 8% as a result of the training in both the healthy and MCI participants.
The atrophy of the brain's cortical layer is a marker of Alzheimer's disease progression and correlates with symptoms including cognitive impairment. Dr. Smith and colleagues found that the study participants who showed the greatest improvements in fitness had the most growth in the cortical layer, including both the group diagnosed with MCI and the healthy elders. While both groups showed strong associations between increased fitness and increased cortical thickness after the intervention, the MCI participants showed greater improvements compared to healthy group in the left insula and superior temporal gyrus, two brain regions that have been shown to exhibit accelerated neurodegeneration in Alzheimer's disease.
Dr. Smith previously reported that the participants in this exercise intervention showed improvements in neural efficiency during memory recall, and these new data add to the evidence for the positive impact of exercise on cognitive function. Other research he has published has also shown that moderate intensity physical activity, such as walking for 30 minutes 3-4 days per week, may protect brain health by staving off shrinkage of the hippocampus in older adults.
This is the first study to show that exercise and improved fitness can impact cortical thickness in older adults diagnosed with mild cognitive impairment. Dr. Smith plans future studies that include more participants engaging in a longer-term exercise intervention to see if greater improvements can be seen over time, and if the effects persist over the long term. The key unanswered question is if regular moderate intensity physical activity could reverse or delay cognitive decline and help keep people out of nursing homes and enable them to maintain their independence as they age.
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/11/151119113458.htm
Physical activity linked to better memory among older adults
November 24, 2015
Science Daily/Boston University Medical Center
Could staying physically active improve quality of life by delaying cognitive decline and prolonging an independent lifestyle? A new study has found that older adults who take more steps either by walking or jogging perform better on memory tasks than those who are more sedentary.
The study examines the relationship between physical activity, memory and cognition in young and old adults. It appears online in the Journal of the International Neuropsychological Society.
The study included 29 young adults (ages 18-31) and 31 older adults (ages 55-82) who wore a small device called an ActiGraph, which recorded information including how many steps each took, how vigorous the steps were and how much time it involved. Participants also completed neuropsychological testing to assess their memory, planning and problem-solving abilities. In addition to standardized neuropsychological tasks of executive function (planning and organization abilities) and long-term memory, participants engaged in a laboratory task in which they had to learn face-name associations.
The researchers found that older adults who took more steps per day had better memory performance. The association between the number of steps taken was strongest with a task that required recalling which name went with a person's face--the same type of everyday task that older adults often have difficulty with. In young adults, the number of steps taken was not associated with memory performance.
According to the researchers these findings demonstrate that the effects of physical activity extend to long-term memory--the same type of memory that is negatively impacted by aging and neurodegenerative dementias such as Alzheimer's disease. ''Our findings that physical activity is positively associated with memory is appealing for a variety of reasons. Everyone knows that physical activity is a critical component to ward off obesity and cardiovascular-related disease. Knowing that a lack of physical activity may negatively impact one's memory abilities will be an additional piece of information to motivate folks to stay more active," explained corresponding author Scott Hayes, PhD, assistant professor of psychiatry at Boston University School of Medicine and the Associate Director of the Neuroimaging Research for Veterans Center at the VA Boston Healthcare System.
The authors point out that staying physically active can take a variety of forms from formal exercise programs to small changes, such as walking or taking the stairs. "More research is needed to explore the specific mechanisms of how physical activity may positively impact brain structure and function as well as to clarify the impact of specific exercise programs (e.g., strength, aerobic, or combined training) or dose of exercise (frequency, intensity, duration) on a range of cognitive functions,'' added Hayes.
The authors emphasize that the objective measurement of physical activity was a key component of the current study, as the majority of studies to date have used self-report questionnaires, which can be impacted by memory failures or biases.
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/11/151124155437.htm
Physical activity may leave the brain more open to change
December 7, 2015
Science Daily/Cell Press
Learning, memory, and brain repair depend on the ability of our neurons to change with experience. Now, researchers have evidence from a small study in people that exercise may enhance this essential plasticity of the adult brain.
https://images.sciencedaily.com/2015/12/151207131508_1_540x360.jpg
This is an artistic representation of the take home messages in Lunghi and Sale: "A cycling lane for brain rewiring," which is that physical activity (such as cycling) is associated with increased brain plasticity.
Credit: Dafne Lunghi Art
The findings focused on the visual cortex come as hopeful news for people with conditions including amblyopia (sometimes called lazy eye), traumatic brain injury, and more, the researchers say.
"We provide the first demonstration that moderate levels of physical activity enhance neuroplasticity in the visual cortex of adult humans," says Claudia Lunghi of the University of Pisa in Italy.
"By showing that moderate levels of physical activity can boost the plastic potential of the adult visual cortex, our results pave the way to the development of non-invasive therapeutic strategies exploiting the intrinsic brain plasticity in adult subjects," she adds.
The plastic potential of the cerebral cortex is greatest early in life, when the developing brain is molded by experience. Brain plasticity is generally thought to decline with age. This decline in the brain's flexibility over time is especially pronounced in the sensory brain, which displays far less plasticity in adults than in younger people.
Lunghi and colleague Alessandro Sale of the National Research Council's Neuroscience Institute were inspired to explore the role of physical activity in brain plasticity by experiments that Sale conducted previously in laboratory animals. Those studies showed that animals performing physical activity--for example rats running on a wheel--showed elevated levels of plasticity in the visual cortex and improved recovery from amblyopia in comparison to more sedentary animals.
To find out whether the same might hold true for people, the researchers measured the residual plastic potential of the adult visual cortex in humans using a simple test of binocular rivalry. Most of the time, our eyes work together. But when people have one eye patched for a short period of time, the closed eye becomes stronger as the visual brain attempts to compensate for the lack of visual input. The strength of the resulting imbalance between the eyes is a measure of the brain's visual plasticity and can be tested by presenting each eye with incompatible images.
In the new study, Lunghi and Sale put 20 adults through this test twice; in one deprivation test, participants with one eye patched watched a movie while relaxing in a chair. In the other test, participants with one eye patched exercised on a stationary bike for ten-minute intervals during the movie. The results were clear: brain plasticity was enhanced by the exercise.
"We found that if, during the two hours of eye patching, the subject intermittently cycles, the perceptual effect of eye patching on binocular rivalry is stronger compared to a condition in which, during the two hours of patching, the subject watches a movie while sitting on a chair. That is, after physical activity, the eye that was patched is strongly potentiated, indicating increased levels of brain plasticity."
While further study is needed, the researchers think that this effect may result from a decrease with exercise in an inhibitory neurotransmitter called GABA. As concentrations of this inhibitory nerve messenger decline, the brain becomes more responsive.
Regardless of the mechanism, the findings suggest that exercise plays an important role in brain health and recovery. They come as especially good news for people with amblyopia, which is generally considered to be untreatable in adults.
"Our study suggests that physical activity, which is also beneficial for the general health of the patient, could be used to increase the efficiency of the treatment in adult patients," Lunghi says. "So, if you have a lazy eye, don't be lazy yourself!"
Lunghi and Sale say they now plan to investigate the effects of moderate levels of physical exercise on visual function in amblyopic adult patients and to look deeper into the underlying neural mechanisms.
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/12/151207131508.htm
Intensive training affects the sleep, performance and mood of athletes, but more carbs may help
December 11, 2015
Science Daily/Taylor & Francis
Getting enough sleep is an essential part of any athlete’s training program, but a new study reveals intensive bouts of exercise can make it hard to get 40 winks. Suspecting that intense exercise can lead to sleep disturbance, scientists studied the effects of two nine day periods of heavy training on 13 highly trained cyclists. The researchers monitored the athletes’ moods, sleep patterns and performance before, during and after exercise.
S.C. Killer and her colleagues discovered that even as little as nine days of intense training can cause 'significant and progressive decline in sleep quality'. They also noticed that the athletes' moods and capacity for exercise both worsened over the period of observation.
Interestingly, the data collected also indicated that the cyclists spent more time in bed during the intense training -- suggesting that they were indeed tired out. But, the extra time under the covers didn't result in any more actual sleep. "Sleep efficiency was significantly reduced during the intensified training period," the researchers observed, with the number of times the athletes woke throughout the night significantly increased. In addition, the cyclists reported changes in their moods as the study went on, including higher tension, anger, fatigue, confusion, depression and increased feelings and symptoms of stress.
As for the additional carbs, the team concluded that a high carbohydrate regime reduced some, but not all, of the effects of hard training. The moderate-carb athletes recorded more sleep time, but this may demonstrate higher levels of fatigue and a greater need for recovery when following that diet.
This study is a key reminder of the importance of sleep to the recovery and performance for all athletes -- as well as the effect that hard training can have on sleep.
As the authors note: "The cycle of successful training must involve overload to a state of acute fatigue, followed by a period of rest. The results of such training are positive adaptations and improvements in performance. However, if overloaded training is not followed by sufficient rest, overreaching may occur."
This study is also a reminder to all coaches of the need to build ample time for rest, including naps, into their athletes' training plans.
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2015/12/151211131723.htm
Exercise reduces heart disease risk in depressed patients
Further evidence regular physical activity is beneficial
January 11, 2016
Science Daily/American College of Cardiology
Symptoms of mild to minimal depression were associated with early indicators of heart disease, say researchers. However, the study found regular exercise seems to reduce the adverse cardiovascular consequences of depression.
Depression has been linked to an increased risk of heart disease and other physical ailments, and depression is commonly associated with worse outcomes for patients with heart disease and other conditions. In addition, as many as 20 percent of people hospitalized with a heart attack report symptoms of depression, while patients with heart disease have three times the risk of developing depression compared to the general population.
Researchers from Emory University Hospital in Atlanta set out to learn more about the relationship between depressive symptoms and heart disease. They studied 965 people who were free of heart disease and who had no prior diagnosis of an affective, psychotic or anxiety disorder. Researchers used questionnaires to evaluate patients for depression and levels of physical activity. They also looked a several early indicators of heart disease.
Researchers found arterial stiffening and inflammation--the early heart disease indicators--that accompany worsening depressive symptoms were more pronounced in people who were inactive. The indicators were less common in subjects engaging in regular physical activity.
"Our findings highlight the link between worsening depression and cardiovascular risk and support routinely assessing depression in patients to determine heart disease risk. This research also demonstrates the positive effects of exercise for all patients, including those with depressive symptoms," said study author Arshed A. Quyyumi, M.D., co-director of the Emory Clinical Cardiovascular Research Institute in Atlanta. "There are many patients with heart disease who also experience depression -- we need to study whether encouraging them to exercise will reduce their risk of adverse outcomes."
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2016/01/160111152808.htm
Exercise for people with dementia improves balance and reduces dependence
January 20, 2016
Science Daily/Umea University
Regular exercise improves balance for people with dementia and reduces dependence on assistance. This according to new research on healthcare for people suffering from dementia.
In a unique study on people with dementia living in residential care facilities, researchers from Umeå University have found that regular functional exercise, similar to everyday activities and performed at high intensity, can improve balance and reduce dependence on assistance in activities of daily living, such as for instance mobility or toilet visits. Training sessions lasting 45 minutes, two to three times per week, can lead to an improved quality of life for individuals suffering from dementia -- a progressive illness leading to gradual reduction in cognitive and physical function.
In 2012, the number of individuals with dementia in Sweden stretched to 150,000 according to the National Board of Health and Welfare (Socialstyrelsen). This is a number expected to reach at least 250,000 in 2050 at the speed of population aging. Having an increased proportion of individuals with dementia in society increases the demand and costs for healthcare. At present, the cost of dementia in Sweden reaches around SEK 60 billion per annum, according to the National Board of Health and Welfare.
"Regular exercise has a positive effect on people with dementia and should, therefore, be included in the care in residential care facilities. Studies such as the present one are rare, but provide important knowledge to further build upon in order to develop care of people with dementia as a cost-effective means of meeting future challenges, and help individuals to maintain independence longer," says Annika Toots, PhD student at the Department of Community Medicine and Rehabilitation at Umeå University, and first author of the article.
The study, described in the article Effects of a high-intensity functional exercise program on dependence in activities of daily living and balance in older adults with dementia, is a part of the greater Umeå Dementia and Exercise Study (UMDEX), performed involving people with dementia in residential care facilities. As a next step, research groups at the Unit of Physiotherapy and Geriatric medicine will analyse which effect exercise has on for instance ability to walk and cognitive ability in the target group, as well as how participants and physiotherapists experienced the exercise programme.
The published study involved 186 people with dementia in 16 different residential care facilities in the Umeå area. All participants were 65 years of age or above and in need of personal care. The participants were randomly allocated into two groups, where one group undertook a high-intensive, functional exercise programme led by physiotherapists. The programme included various functional exercises that aimed to improve leg strength, balance and walking, which are part of everyday activities. The workout covered 45 minutes, two to three times per week for a duration of four months.
Instead of training, the sedentary control group took part in stimulating activities of group conversations, singing and reading aloud sessions. The purpose of this was to control the positive effects that stimulation through togetherness and attention have. All participants were tested before, as well as four and seven months after the completion of the programme.
Due to the progressive course of dementia, a deterioration was noted in all participants' abilities to independently manage everyday activities. The deterioration occurred at a slower pace in the exercise group and they showed an improved balance. The positive effects of the exercise varied depending on the type of dementia, where the group with vascular dementia experienced better effects of exercising than participants with Alzheimer's disease. To better plan and carry out exercise for people with dementia, it can, therefore, be of importance to identify the type of dementia.
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2016/01/160120115733.htm
Sustained aerobic exercise increases adult neurogenesis in brain
February 8, 2016
Suomen Akatemia (Academy of Finland)
It may be possible to increase the neuron reserve of the hippocampus – and thus improve preconditions for learning – by promoting neurogenesis via sustained aerobic exercise such as running, say researchers.
Aerobic exercise, such as running, has positive effects on brain structure and function, for example, the generation of neurons (neurogenesis) in the hippocampus, a brain structure important in learning. It has been unclear whether high-intensity interval training (HIT), referring to alternating short bouts of very intense anaerobic exercise with recovery periods, or anaerobic resistance training has similar effects on hippocampal neurogenesis in adulthood. In addition, individual genetic variation in the overall response to physical exercise likely plays a part in the effects of exercise on adult neurogenesis but is less studied.
Researchers from the Department of Psychology and from the Department of Biology of Physical Activity at the University of Jyväskylä studied the effects of sustained running exercise, HIT and resistance training on adult hippocampal neurogenesis in adult male rats. In addition to the commonly used Sprague-Dawley rats, rat lines developed by collaborators at the University of Michigan were also used: Rats with a genetically high response to aerobic training (HRT) and those with a low response to aerobic training (LRT). The exercise training period was 6 to 8 weeks (running, HIT or resistance training) during which control animals of the same rat line/strain remained in sedentary conditions in the home cage.
The results indicate that the highest number of new hippocampal neurons was observed in rats that ran long distances and that also had a genetic predisposition to benefit from aerobic exercise: Compared to sedentary animals, HRT rats that ran voluntarily on a running wheel had 2-3 times more new hippocampal neurons at the end of the experiment. Resistance training had no such effect. Also the effects of HIT were minor. To conclude, only sustained aerobic exercise improved hippocampal neurogenesis in adult animals.
The result is important because, according to previous research, the new hippocampal neurons produced as a result of neurogenesis are needed among other things for learning temporally and/or spatially complex tasks. It is possible that by promoting neurogenesis via sustained aerobic exercise, the neuron reserve of the hippocampus can be increased and thus also the preconditions for learning improved -- also in humans
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2016/02/160208083606.htm
Aerobic fitness may protect liver against chronic alcohol use
Higher metabolism from aerobic activity could prevent liver inflammation
February 16, 2016
Science Daily/University of Missouri-Columbia
Excessive alcohol use is responsible for more than 80,000 deaths in the United States each year. Over time, excessive drinking can lead to several chronic conditions, such as fatty liver disease and cirrhosis. Now, a study shows that aerobic exercise may protect the liver against alcohol-related inflammation and injury.
"Excessive alcohol consumption is one of the most common causes of chronic liver failure," said Jamal Ibdah, M.D., Ph.D., professor of medicine, Raymond E. and Vaona H. Peck Chair in Cancer Research at the MU School of Medicine and lead author of the study. "We know from previous research that chronic and binge drinking causes modifications to protein structures within the liver, resulting in irreversible damage. In our current study we wanted to see whether increased levels of aerobic fitness could prevent alcohol-related liver damage."
Ibdah's research team used rats bred for high activity, or "runner rats," to test if increased metabolism protected the liver against fatty deposits and inflammation. One group of rats was exposed to chronic alcohol use for six weeks and compared to a second group that was not exposed to alcohol during the same time period.
"As expected, we found that fatty deposits were greater in the livers of the chronic alcohol group," said Ibdah, who also serves as director of the Division of Gastroenterology and Hepatology at the MU School of Medicine. "However, chronic alcohol ingestion did not cause significant inflammation in the liver. Higher physical activity levels seemed to protect against the metabolic dysfunction that eventually leads to irreversible liver damage."
Ibdah's team also found that chronic alcohol ingestion caused no discernable increase in free fatty acids, triglycerides, insulin or glucose in the blood of the group exposed to alcohol as compared to the control group.
"This is significant because chronic alcohol ingestion may reduce insulin effectiveness over time, leading to elevated blood insulin and sugar levels," Ibdah said. "With chronic use, we would expect to see these levels much higher than the control group, yet surprisingly, they were about the same."
Ibdah said more research is needed to better understand how increased aerobic fitness provides oxidative protection against chronic alcohol use. However, understanding this mechanism may lead to eventual treatments for chronic alcohol-related liver damage.
Science Daily/SOURCE :https://www.sciencedaily.com/releases/2016/02/160216123453.htm
How a waste product of exercise protects neurons from trauma damage
February 19, 2016
Science Daily/Ecole Polytechnique Fédérale de Lausanne
Researchers have found how lactate, a waste product of glucose metabolism can protect neurons from damage following acute trauma such as stroke or spinal cord injury.
https://images.sciencedaily.com/2016/02/160219092202_1_540x360.jpg
Step-by-step description of how lactate protects neurons against excitotoxicity: (1) Excessive glutamate activity triggers a strong influx of calcium (Ca2+) into the neuron through NMDA receptors, which leads to cell death. (2) Lactate is transported into the neuron and (3) converted to pyruvate by the enzyme lactate dehydrogenase (LDH). (4) Pyruvate is then transported into mitochondria by the mitochondrial pyruvate carrier (MPC) where it generates ATP. (5) ATP is then released through pannexins and activates the receptor P2Y, which (6) activates the PI3K pathway. (7) This triggers the opening of potassium channels (K+), which causes the neuron to hyperpolarize, decreasing the neuron's excitability, and thus protecting it from excitotoxic damage.
Credit: Pascal Jourdain (EPFL)
Stroke or spinal cord injury can cause nerve cells to receive excessive stimulation, which ultimately damages and even kills them. This process is known as excitotoxicity, and it is one of the reasons why time following such trauma is critical, while it also implicated in progressive neurodegenerative diseases, e.g. Alzheimer's disease. A team of scientists led by EPFL has now discovered that lactate, which is produced in the brain and even muscles after intense exercise, can be used to protect neurons against excitotoxicity. The study is published in the Nature journal Scientific Reports.
Following acute trauma such as a stroke or spinal cord injury, a certain type of receptors go into overdrive and overwhelm the target neuron with a barrage of electrical signals. This causes a build-up of calcium ions inside the neuron, which triggers toxic biochemical pathways that ultimately damage or kill it.
The receptors that cause this are called NMDA receptors, and interact with the neurotransmitter glutamate. NMDA receptors are a major target in research and medicine, as they are implicated in a number of disorders, including epilepsy, schizophrenia, Parkinson's and even Alzheimer's.
A team of researchers led by Pierre Magistretti from EPFL and the King Abdullah University of Science and Technology, investigated the effects of glutamate on cultured neurons from the brains of mice. The scientists used a new, non-invasive imaging technique called Digital Holographic Microscopy that can visualize cells structure and dynamics with nanometer-level resolution.
Previous studies have suggested that, lactate could protect neurons against excitotoxicity. Lactate is produced in the brain and in muscles after intense exercise as a waste product of glucose metabolism. Nonetheless, how lactate protects neurons has eluded scientists until now.
The researchers tested the effects of glutamate on the mouse neurons with and without lactate. The results were revealing: glutamate killed 65% of the neurons, but when with lactate, that number dropped to 32%.
The researchers then aimed to determine how lactate protects neurons. By using different receptor blockers on the mouse neurons, they determined that lactate triggers the production of ATP, the cell's energy molecule. In turn, the produced ATP binds and activates another type of receptor in the neuron, which turns on a complex cascade of defense mechanisms. As a result, the neuron can withstand the onslaught of signals from the NMDA receptor.
The breakthrough can advance our understanding of neuroprotection, which could lead to improved pharmacological ways to ameliorate the irreparable damage caused by stroke, spinal cord injury, and other trauma.
Science Daily/SOURCE :https://www.sciencedaily.com/releases/2016/02/160219092202.htm