It's not your fitness tracker -- it's you
When it comes to measuring fitness, no one gets it right
April 12, 2018
Science Daily/University of Southern California
An international study reveals that no one defines physical activity the same way when they are asked to report how much they exercise. The findings are a caution for researchers trying to make cross-cultural comparisons about exercise.
An American, a Brit and a Dutch guy go for a walk. That may sound like the beginning of a joke, but it's actually the end of a USC-led study that could impact future research on physical activity.
With the help of fitness-tracking devices, an international team of scientists studied how physically active people consider themselves to be, versus how physically active they really are.
The research has revealed that no one gets it right. The American responses suggest they are as active as the Dutch or the English. Older people think they are as active as young people. In reality, though, Americans are much less active than the Europeans and older people are less active than the young.
Does this mean Americans are liars about their physical activity, or the Dutch and the English humbly underestimate theirs?
"It means people in different countries or at different age groups can have vastly different interpretations of the same survey questions," says Arie Kapteyn, the study's lead author and executive director of the Center for Economic and Social Research at the USC Dornsife College of Letters, Arts and Sciences.
Kapteyn believes the differences in fitness perceptions are driven by cultural and environmental differences.
For instance, Americans are largely dependent on cars while the Dutch frequently walk or ride bicycles to work and for simple errands, Kapteyn says.
The study was published on April 11 in the Journal of Epidemiology & Community Health.
Perception vs. reality
For the study, the scientists tracked 540 participants from the United States, 748 people from the Netherlands and 254 from England.
Men and women in the study, ages 18 and up, were asked in a survey to report their physical activity on a five-point scale, ranging from inactive to very active. They also wore a fitness-tracking device on their wrist (an accelerometer) so that scientists could measure their actual physical activity over a seven-day period.
The researchers found that the Dutch and English were slightly more likely to rate themselves toward the "moderate" center of the scale, while Americans tended to rate themselves at the extreme ends of the scale, either as "very active" or "inactive." But overall, the differences in how people from all three countries self-reported their physical activity was modest or non-existent.
The wearable devices revealed hard truths: Americans were much less physically active than both the Dutch and English. In fact, the percentage of Americans in the inactive category was nearly twice as large as the percentage of Dutch participants.
Reality bytes by age group
A comparison of fitness tracker data by age group reveals that people in all three countries are generally less active as they get older. That said, inactivity appeared more widespread among older Americans than participants in the other countries: 60 percent of Americans were inactive, compared to 42 percent of the Dutch and 32 percent of the English.
The researchers found that, in all three countries, the disparities between perceived and real activity levels were greatest among participants who reported that they were either "very active" or "very inactive."
"Individuals in different age groups simply have different standards of what it means to be physically active," said Kapteyn. "They adjust their standards based on their circumstances, including their age."
Kapteyn says that since physical activity is so central to a healthy life, accurate measurements are important to science. The findings indicate that scientists should proceed with caution when interpreting and comparing the results of international fitness studies that have utilized standardized questionnaires.
"When you rely on self-reported data, you're not only relying on people to share a common understanding of survey terms, but to accurately remember the physical activity that they report," says Kapteyn. "With the wide availability of low-cost activity tracking devices, we have the potential to make future studies more reliable."
https://www.sciencedaily.com/releases/2018/04/180412102746.htm
Brain differences in athletes playing contact vs. non-contact sports
April 5, 2018
Science Daily/Indiana University
A study has found differences in the brains of athletes who participate in contact sports compared to those who participate in non-contact sports.
The differences were observed as both groups were given a simple visual task. The results could suggest that a history of minor but repeated blows to the head can result in compensatory changes to the brain as it relates to eye movement function. Or it could show how the hundreds of hours that contact sport players spend on eye-hand coordination skills leads to a reorganization of the brain in the areas dedicated to eye movements.
While more research is needed, senior author Nicholas Port said the findings contribute important information to research on subconcussive blows -- or "microconcussions" -- that are common in sports such as football, soccer, ice hockey, snowboarding and skiing. Interest in subconcussions has grown significantly in recent years as the long- and short-term risks of concussions -- or mild traumatic brain injury -- have become more widely known and understood.
"The verdict is still out on the seriousness of subconcussions, but we've got to learn more since we're seeing a real difference between people who participate in sports with higher risk for these impacts," said Port, an associate professor in the IU School of Optometry. "It's imperative to learn whether these impacts have an actual effect on cognitive function -- as well as how much exposure is too much."
To conduct the study, Port and researchers in the IU Bloomington Department of Psychological and Brain Sciences scanned the brains of 21 football players and 19 cross-country runners using fMRI technology.
The researchers focused on these sports because football is a physical game in which small but repeated blows to the head are common, whereas cross-country is extremely low risk for such impacts. The contact sport players did not have a history of concussion, but these sports are known to lead to repeat subconcussive blows.
The researchers also scanned the brains of 11 non-college-level athletes from socioeconomic backgrounds similar to the football players to ensure their scan results were not rooted in factors unrelated to their sport.
The differences in football players' versus cross-country runners' brains were specifically seen in regions of the brain responsible for visual processing. These regions were much more active in football players versus cross-country runners or volunteers who did not play college sports.
"We focused on these brain regions because physicians and trainers regularly encounter large deficits in players' ability to smoothly track a moving point with their eyes after suffering an acute concussion," Port said.
Although there were clear differences between the brains of the football players and the cross-country runners, Port said interpretation of the study's results is challenging.
"Everyone from musicians to taxi drivers has differences in brain activity related to their specific skills," he said. "The differences in this study may reflect a lifetime exposure of subconcussive blows to the head, or they could simply be the result of playing a visually demanding sport where you're constantly using your hands and tracking the ball."
The ideal way to find the root cause of these differences would be a similar analysis using only football players, he said. The next generation of wearable accelerometers to measure physical impact during play will greatly enhance researchers' ability to confidently sort players of the same sport into groups based on exposure to subconcussions.
https://www.sciencedaily.com/releases/2018/04/180405120319.htm
Stopping exercise can increase symptoms of depression
March 22, 2018
Science Daily/University of Adelaide
PhD student Julie Morgan from the University of Adelaide's Discipline of Psychiatry has reviewed the results of earlier studies that examined the effects of stopping exercise in regularly active adults.
The results of her review are now published online ahead of print in the Journal of Affective Disorders.
"Adequate physical activity and exercise are important for both physical and mental health," says Ms Morgan.
"Current public health guidelines recommend being active on most if not all days of the week. At least 150 minutes of moderate intensity exercise a week is recommended to maintain health and prevent depression, or 75 minutes of vigorous intensity exercise for added health benefits.
"An extensive body of clinical evidence shows that regular exercise can reduce and treat depression. However, there is limited research into what happens with depressive symptoms when exercise is stopped," she says.
Ms Morgan reviewed studies that investigated the cessation of exercise in 152 adults. They had each undertaken at least 30 minutes of exercise, three times a week, for a minimum of three months.
"In some cases, ceasing this amount of exercise induced significant increases in depressive symptoms after just three days," says Professor Bernhard Baune, Head of Psychiatry at the University of Adelaide and senior author on the paper.
"Other studies showed that people's depressive symptoms increased after the first one or two weeks, which is still quite soon after stopping their exercise."
Professor Baune says the depressive symptoms arising from stopping exercise occurred in the absence of the typical biological markers commonly involved with depressive symptoms.
"This suggests some kind of novel effect in these cases, although we should add some caution here, as the number of people included in the studies we examined was small. Such findings would need to be replicated in additional trials," he says.
Professor Baune says the lack of research in this specific area points to the need for further studies, to help better understand the way in which stopping exercise affects depressive symptoms.
"For now, it is important that people understand the potential impact on their mental well-being when they suddenly cease regular exercise," he says.
https://www.sciencedaily.com/releases/2018/03/180322112720.htm
Poor fitness linked to weaker brain fiber, higher dementia risk
February 14, 2018
Science Daily/UT Southwestern Medical Center
Scientists have more evidence that exercise improves brain health and could be a lifesaving ingredient that prevents Alzheimer's disease.
In particular, a new study from UT Southwestern's O'Donnell Brain Institute suggests that the lower the fitness level, the faster the deterioration of vital nerve fibers in the brain. This deterioration results in cognitive decline, including memory issues characteristic of dementia patients.
"This research supports the hypothesis that improving people's fitness may improve their brain health and slow down the aging process," said Dr. Kan Ding, a neurologist from the Peter O'Donnell Jr. Brain Institute who authored the study.
White matter
The study published in the Journal of Alzheimer's Disease focused on a type of brain tissue called white matter, which is composed of millions of bundles of nerve fibers used by neurons to communicate across the brain.
Dr. Ding's team enrolled older patients at high risk to develop Alzheimer's disease who have early signs of memory loss, or mild cognitive impairment (MCI). The researchers determined that lower fitness levels were associated with weaker white matter, which in turn correlated with lower brain function.
Distinctive tactics
Unlike previous studies that relied on study participants to assess their own fitness, the new research objectively measured cardiorespiratory fitness with a scientific formula called maximal oxygen uptake. Scientists also used brain imaging to measure the functionality of each patient's white matter.
Patients were then given memory and other cognitive tests to measure brain function, allowing scientists to establish strong correlations between exercise, brain health, and cognition.
Lingering mysteries
The study adds to a growing body of evidence pointing to a simple yet crucial mandate for human health: Exercise regularly.
However, the study leaves plenty of unanswered questions about how fitness and Alzheimer's disease are intertwined. For instance, what fitness level is needed to notably reduce the risk of dementia? Is it too late to intervene when patients begin showing symptoms?
Some of these topics are already being researched through a five-year national clinical trial led by the O'Donnell Brain Institute.
The trial, which includes six medical centers across the country, aims to determine whether regular aerobic exercise and taking specific medications to reduce high blood pressure and cholesterol levels can help preserve brain function. It involves more than 600 older adults at high risk to develop Alzheimer's disease.
"Evidence suggests that what is bad for your heart is bad for your brain. We need studies like this to find out how the two are intertwined and hopefully find the right formula to help prevent Alzheimer's disease," said Dr. Rong Zhang of UT Southwestern, who oversees the clinical trial and is Director of the Cerebrovascular Laboratory in the Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas, where the Dallas arm of the study is being carried out.
Prior findings
The research builds upon prior investigations linking healthy lifestyles to better brain function, including a 2013 study from Dr. Zhang's team that found neuronal messages are more efficiently relayed in the brains of older adults who exercise.
In addition, other teams at the O'Donnell Brain Institute are designing tests for the early detection of patients who will develop dementia, and seeking methods to slow or stop the spread of toxic proteins associated with the disease such as beta-amyloid and tau, which are blamed for destroying certain groups of neurons in the brain.
"A lot of work remains to better understand and treat dementia," said Dr. Ding, Assistant Professor of Neurology & Neurotherapeutics. "But, eventually, the hope is that our studies will convince people to exercise more."
https://www.sciencedaily.com/releases/2018/02/180214181952.htm
Everyday activities associated with more gray matter in brains of older adults
Study measured amount of lifestyle physical activity such as house work, dog walking and gardening
February 14, 2018
Science Daily/Rush University Medical Center
Higher levels of lifestyle physical activity are associated with more gray matter in the brains of older adults, according to a new study.
The gray matter in the brain includes regions responsible for controlling muscle movement, experiencing the senses, thinking and feeling, memory and speech and more. The volume of gray matter is a measure of brain health, but the amount of gray matter in the brain often begins to decrease in late adulthood, even before symptoms of cognitive dysfunction appear.
"More gray matter is associated with better cognitive function, while decreases in gray matter are associated with Alzheimer's disease and other related dementias," said Shannon Halloway, PhD, the lead author of the Journal of Gerontology paper and the Kellogg/Golden Lamp Society Postdoctoral Fellow in the Rush University College of Nursing. "A healthy lifestyle, such as participating in lifestyle physical activity, is beneficial for brain health, and may help lessen gray matter atrophy (decreases)."
Study used accelerometer to measure activity of 262 older adults
The study measured the levels of lifestyle physical activity by 262 older adults in Rush's Memory and Aging Project, an ongoing epidemiological cohort study. Participants are recruited from retirement communities and subsidized housing facilities in and around Chicago to participate in annual clinical evaluations and magnetic resonance imaging (MRI) scans, and to donate their brains and other parts of their bodies for research after their deaths.
Participants in the lifestyle study wore a non-invasive device called an accelerometer continuously for seven to ten days. The goal was to accurately measure the frequency, duration and intensity of a participant's activities over that time.
Lifestyle physical activity is "more realistic for older adults" than a structured exercise program that might require them to go to a gym, according to Halloway.
"Accessibility becomes an issue as one ages," Halloway said. "Transportation can be a problem. Gym settings can be intimidating for any individual, but especially so for older adults."
Accelerometers provide more precise measures of activity
The use of accelerometers was only one of the ways in which this analysis differed from some other investigations of the health of older people. Most research that explores the effects of exercise relies on questionnaires, which ask participants to "self-report" their levels of activity, Halloway said. She added that questionnaires tend to ask in a fairly non-specific fashion about types and intensity of exercise.
The real problem with questionnaires, though, is that "sometimes, we get really inaccurate reports of activity," Halloway acknowledged. "People commonly over-estimate, and on the flip side, some underestimate the lifestyle activity they're getting from things they don't consider exercise, like household chores, for example."
As to the accelerometer, she says, "it's not as commonly used (in studies of exercise) as we would like," even though accelerometers provide more precise results than self-reporting.
Study provided insights into activity levels of people past 80
Another departure in Halloway's study from some other investigations was the opportunity she had to assess the effects of exercise on individuals older than 80. In fact, the mean age in this study was 81 years, compared with 70 years for other studies Halloway used as a reference.
"One great strength of the Rush Alzheimer's Disease Center is its amazing ability to follow up with participants, and its high retention rates of participants," Halloway says. As a result, the Memory and Aging Project captures a number of participants in that older age group.
However, no one was included in Halloway's analysis who had a diagnosis or symptoms of dementia, or even mild cognitive impairment; a history of brain surgery; or brain abnormalities such as tumors, as seen on MRIs.
The study compared gray matter volumes as seen in participants' MRIs with readings from the accelerometers and other data, which all were obtained during the same year. Halloway's analysis found the association between participants' actual physical activity and gray matter volumes remained after further controlling for age, gender, education levels, body mass index and symptoms of depression, all of which are associated with lower levels of gray matter in the brain.
"Our daily lifestyle physical activities are supportive of brain health, and adults of all ages should continue to try and increase lifestyle physical activity to gain these benefits," Halloway said. "Moving forward, our goal is to develop and test behavioral interventions that focus on lifestyle physical activity for older adults at increased risk for cognitive decline due to cardiovascular disease,"
https://www.sciencedaily.com/releases/2018/02/180214093828.htm
Running helps brain stave off effects of chronic stress
Exercise protects vital memory and learning functions
February 14, 2018
Science Daily/Brigham Young University
The study finds that running mitigates the negative impacts chronic stress has on the hippocampus, the part of the brain responsible for learning and memory.
Most people agree that getting a little exercise helps when dealing with stress. A new BYU study discovers exercise -- particularly running -- while under stress also helps protect your memory.
The study, newly published in the journal of Neurobiology of Learning and Memory, finds that running mitigates the negative impacts chronic stress has on the hippocampus, the part of the brain responsible for learning and memory.
"Exercise is a simple and cost-effective way to eliminate the negative impacts on memory of chronic stress," said study lead author Jeff Edwards, associate professor of physiology and developmental biology at BYU.
Inside the hippocampus, memory formation and recall occur optimally when the synapses or connections between neurons are strengthened over time. That process of synaptic strengthening is called long-term potentiation (LTP). Chronic or prolonged stress weakens the synapses, which decreases LTP and ultimately impacts memory. Edwards' study found that when exercise co-occurs with stress, LTP levels are not decreased, but remain normal.
To learn this, Edwards carried out experiments with mice. One group of mice used running wheels over a 4-week period (averaging 5 km ran per day) while another set of mice was left sedentary. Half of each group was then exposed to stress-inducing situations, such as walking on an elevated platform or swimming in cold water. One hour after stress induction researchers carried out electrophysiology experiments on the animals' brains to measure the LTP.
Stressed mice who had exercised had significantly greater LTP than the stressed mice who did not run. Edwards and his colleagues also found that stressed mice who exercised performed just as well as non-stressed mice who exercised on a maze-running experiment testing their memory. Additionally, Edwards found exercising mice made significantly fewer memory errors in the maze than the sedentary mice.
The findings reveal exercise is a viable method to protect learning and memory mechanisms from the negative cognitive impacts of chronic stress on the brain.
"The ideal situation for improving learning and memory would be to experience no stress and to exercise," Edwards said. "Of course, we can't always control stress in our lives, but we can control how much we exercise. It's empowering to know that we can combat the negative impacts of stress on our brains just by getting out and running."
https://www.sciencedaily.com/releases/2018/02/180214093823.htm
Caffeine’s sport performance advantage for infrequent tea and coffee drinkers
January 19, 2018
Dublin City University
Sports scientists have found that the performance enhancing benefits of caffeine are more apparent in athletes who do not drink caffeine-rich drinks such as tea, coffee, and energy drinks on a daily basis.
Researchers Dr Brendan Egan and Mark Evans from the DCU School of Health and Human Performance examined the impact of caffeine, in the form of caffeinated chewing gum, on the performance of 18 male team sport athletes during a series of repeated sprints. The athletes undertook 10 repeated sprints under conditions with and without two sticks of the caffeinated gum, which is equivalent to two strong cups of coffee.
They found that the caffeinated gum provided very little advantage to athletes whose bodies may have become desensitised to caffeine through a process called habituation, which occurs by having caffeine frequently.
However, the athletes who had a low habitual caffeine consumption maintained their performance in repeated sprint tests after ingesting a caffeinated chewing gum, while the performance of athletes who consumed the caffeine equivalent of three or more cups of coffee per day worsened over the course of the ten repeated sprints. This indicated that this second group did not benefit from caffeine as a performance aid.
Caffeine is regarded as one of the most popular performance enhancing supplements among athletes. Its benefits include improved muscle strength, mental alertness, as well as reducing the perception of effort during intense activity, therefore helping athletes to perform faster and longer.
The findings from the DCU-led study were published in the International Journal of Sport Nutrition and Exercise Metabolism. They recommended that athletes who consume caffeine on a regular basis should reduce their consumption in the lead-up to a big performance, if they want to receive the benefits of a caffeine supplement as a performance aid.
https://www.sciencedaily.com/releases/2018/01/180119090348.htm
Don’t like going to the gym? It could be your personality
January 10, 2018
Science Daily/British Psychological Society (BPS)
The effectiveness of someone’s exercise regime may depend on their individual personality type, with more creative people better suited to outdoor activities.
That is the key finding of research being presented today, Thursday 11 January, by John Hackston, Chartered Psychologist and Head of Thought Leadership at OPP, at the British Psychological Society's annual conference of the Division of Occupational Psychology in Stratford-upon-Avon.
John Hackston said:
"We were keen to investigate how organisations could help their staff's development through exercise, finding that matching an individual's personality type to a particular type of exercise can increase both the effectiveness and the person's enjoyment of it."
More than 800 people from a range of businesses across several countries were surveyed for the study, which found that people with extraverted personality types were more likely to prefer exercising at the gym.
Staff with a preference for objective logic were also more likely to stick with a regimented exercise plan than those who view feelings and values as being more important.
More creatively minded staff, particularly those who enjoy working with new ideas, were much better suited to outdoor activities such as cycling and running when compared to a structured gym regime.
John Hackston added:
"The most important piece of advice to come out of this research is that there is not one type of exercise that is suited to everyone.
"There can be pressure to follow the crowd to the gym or sign up to the latest exercise fad, but it would be much more effective for them to match their personality type to an exercise plan that is more likely to last the test of time.
"Organisations can help their staff to improve their fitness using this research, with increased fitness potentially leading to lower illness-related absences and increased employee satisfaction."
https://www.sciencedaily.com/releases/2018/01/180110223412.htm
Try exercise to improve memory and thinking, new guideline urges
December 28, 2017
Science Daily/Mayo Clinic
For patients with mild cognitive impairment, don't be surprised if your health care provider prescribes exercise rather than medication. A new guideline for medical practitioners says they should recommend twice-weekly exercise to people with mild cognitive impairment to improve memory and thinking.
The recommendation is part of an updated guideline for mild cognitive impairment published in the Dec. 27 online issue of Neurology, the medical journal of the American Academy of Neurology.
"Regular physical exercise has long been shown to have heart health benefits, and now we can say exercise also may help improve memory for people with mild cognitive impairment," says Ronald Petersen, M.D., Ph.D., lead author, director of the Alzheimer's Disease Research Center, Mayo Clinic, and the Mayo Clinic Study of Aging. "What's good for your heart can be good for your brain." Dr. Petersen is the Cora Kanow Professor of Alzheimer's Disease Research.
Mild cognitive impairment is an intermediate stage between the expected cognitive decline of normal aging and the more serious decline of dementia. Symptoms can involve problems with memory, language, thinking and judgment that are greater than normal age-related changes.
Generally, these changes aren't severe enough to significantly interfere with day-to-day life and usual activities. However, mild cognitive impairment may increase the risk of later progressing to dementia caused by Alzheimer's disease or other neurological conditions. But some people with mild cognitive impairment never get worse, and a few eventually get better.
The academy's guideline authors developed the updated recommendations on mild cognitive impairment after reviewing all available studies. Six-month studies showed twice-weekly workouts may help people with mild cognitive impairment as part of an overall approach to managing their symptoms.
Dr. Petersen encourages people to do aerobic exercise: Walk briskly, jog, whatever you like to do, for 150 minutes a week -- 30 minutes, five times or 50 minutes, three times. The level of exertion should be enough to work up a bit of a sweat but doesn't need to be so rigorous that you can't hold a conversation. "Exercising might slow down the rate at which you would progress from mild cognitive impairment to dementia," he says.
Another guideline update says clinicians may recommend cognitive training for people with mild cognitive impairment. Cognitive training uses repetitive memory and reasoning exercises that may be computer-assisted or done in person individually or in small groups. There is weak evidence that cognitive training may improve measures of cognitive function, the guideline notes.
The guideline did not recommend dietary changes or medications. There are no drugs for mild cognitive impairment approved by the U.S. Food and Drug Administration.
More than 6 percent of people in their 60s have mild cognitive impairment across the globe, and the condition becomes more common with age, according to the American Academy of Neurology. More than 37 percent of people 85 and older have it.
With such prevalence, finding lifestyle factors that may slow down the rate of cognitive impairment can make a big difference to individuals and society, Dr. Petersen notes.
"We need not look at aging as a passive process; we can do something about the course of our aging," he says. "So if I'm destined to become cognitively impaired at age 72, I can exercise and push that back to 75 or 78. That's a big deal."
The guideline, endorsed by the Alzheimer's Association, updates a 2001 academy recommendation on mild cognitive impairment. Dr. Petersen was involved in the development of the first clinical trial for mild cognitive impairment and continues as a worldwide leader researching this stage of disease when symptoms possibly could be stopped or reversed.
https://www.sciencedaily.com/releases/2017/12/171228145026.htm
Short-term exercise equals big-time brain boost
Even a one-time, brief burst of exercise can improve focus, problem-solving
December 21, 2017
Science Daily/University of Western Ontario
A 10-minute, one-time burst of exercise can measurably boost your brain power, at least temporarily, researchers at Western University in London, Canada, have found.
While other studies have showed brain-health benefits after 20-minutes of a single-bout of exercise, or following commitment to a long-term (24-week) exercise program, this research suggests even 10 minutes of aerobic activity can prime the parts of the brain that help us problem-solve and focus.
"Some people can't commit to a long-term exercise regime because of time or physical capacity," said Kinesiology Prof. Matthew Heath, who is also a supervisor in the Graduate Program in Neuroscience and, with master's student Ashna Samani, conducted the study. "This shows that people can cycle or walk briskly for a short duration, even once, and find immediate benefits."
During the study, research participants either sat and read a magazine or did 10 minutes of moderate-to-vigorous exercise on a stationary bicycle. Following the reading and exercise session, the researchers used eye-tracking equipment to examine participants' reaction times to a cognitively demanding eye movement task. The task was designed to challenge areas of the brain responsible for executive function such as decision-making and inhibition.
"Those who had exercised showed immediate improvement. Their responses were more accurate and their reaction times were up to 50 milliseconds shorter than their pre-exercise values. That may seem minuscule but it represented a 14-per-cent gain in cognitive performance in some instances," said Heath, who is also an associate member of Western's Brain and Mind institute. He is conducting a study now to determine how long the benefits may last following exercise.
The work has significance for older people in early stages of dementia who may be less mobile, he said, and for anyone else looking to gain quick a mental edge in their work.
"I always tell my students before they write a test or an exam or go into an interview -- or do anything that is cognitively demanding -- they should get some exercise first," Heath said. "Our study shows the brain's networks like it. They perform better.
https://www.sciencedaily.com/releases/2017/12/171221122543.htm
Working memory positively associated with higher physical endurance, better cognitive function
Suboptimal cardiovascular health, smoking are associated with less cohesive brain network
December 5, 2017
Science Daily/The Mount Sinai Hospital / Mount Sinai School of Medicine
A positive relationship has been found between the brain network associated with working memory -- the ability to store and process information relevant to the task at hand -- and healthy traits such as higher physical endurance and better cognitive function
These traits were associated with greater cohesiveness of the working memory brain network while traits indicating suboptimal cardiovascular and metabolic health, and suboptimal health habits including binge drinking and regular smoking, were associated with less cohesive working memory networks.
This is the first study to establish the link between working memory and physical health and lifestyle choices.
The results of the study will be published online in Molecular Psychiatry.
The research team took brain scans of 823 participants in the Human Connectome Project (HCP), a large brain imaging study funded by the National Institutes of Health, while they performed a task involving working memory, and extracted measures of brain activity and connectivity to create a brain map of working memory. The team then used a statistical method called sparse canonical correlation to discover the relationships between the working memory brain map and 116 measures of cognitive ability, physical and mental health, personality, and lifestyle choices. They found that cohesiveness in the working memory brain map was positively associated with higher physical endurance and better cognitive function. Physical traits such as high body mass index, and suboptimal lifestyle choices including binge alcohol drinking and regular smoking, had the opposite association.
"Working memory accounts for individual differences in personal, educational, and professional attainment," said Sophia Frangou, MD, PhD, Professor of Psychiatry at the Icahn School of Medicine at Mount Sinai. "Working memory is also one of the brain functions that is severely affected by physical and mental illnesses. Our study identified factors that can either support or undermine the working memory brain network. Our findings can empower people to make informed choices about how best to promote and preserve brain health."
https://www.sciencedaily.com/releases/2017/12/171205091531.htm
Exercise increases brain size
November 13, 2017
Science Daily/NICM, Western Sydney University
Aerobic exercise can improve memory function and maintain brain health as we age, a new study has found.
In a first of its kind international collaboration, researchers from Australia's National Institute of Complementary Medicine at Western Sydney University and the Division of Psychology and Mental Health at the University of Manchester in the UK examined the effects of aerobic exercise on a region of the brain called the hippocampus, which is critical for memory and other brain functions.
Brain health decreases with age, with the average brain shrinking by approximately five per cent per decade after the age of 40.
Studies in mice and rats have consistently shown that physical exercise increases the size of the hippocampus but until now evidence in humans has been inconsistent.
The researchers systematically reviewed 14 clinical trials which examined the brain scans of 737 people before and after aerobic exercise programs or in control conditions.
The participants included a mix of healthy adults, people with mild cognitive impairment such as Alzheimer's and people with a clinical diagnosis of mental illness including depression and schizophrenia. Ages ranged from 24 to 76 years with an average age of 66.
The researchers examined effects of aerobic exercise, including stationary cycling, walking, and treadmill running. The length of the interventions ranged from three to 24 months with a range of 2-5 sessions per week.
Overall, the results -- published in the journal NeuroImage -- showed that, while exercise had no effect on total hippocampal volume, it did significantly increase the size of the left region of the hippocampus in humans.
Lead author, NICM postdoctoral research fellow, Joseph Firth said the study provides some of the most definitive evidence to date on the benefits of exercise for brain health.
"When you exercise you produce a chemical called brain-derived neurotrophic factor (BDNF), which may help to prevent age-related decline by reducing the deterioration of the brain," Mr Firth said.
"Our data showed that, rather than actually increasing the size of the hippocampus per se, the main 'brain benefits' are due to aerobic exercise slowing down the deterioration in brain size. In other words, exercise can be seen as a maintenance program for the brain."
Mr Firth said along with improving regular 'healthy' ageing, the results have implications for the prevention of ageing-related neurodegenerative disorders such as Alzheimer's and dementia -- however further research is needed to establish this.
Interestingly, physical exercise is one of the very few 'proven' methods for maintaining brain size and functioning into older age.
https://www.sciencedaily.com/releases/2017/11/171113195024.htm
Should exercise be what the doctor orders for depression?
November 8, 2017
Science Daily/Michigan State University
More mental health providers may want to take a closer look at including exercise in their patients' treatment plans, a new study suggests. Researchers asked 295 patients receiving treatment at a mental health clinic whether they wanted to be more physically active and if exercise helped improve their mood and anxiety. They also asked if patients wanted their therapist to help them become more active.
Michigan State University and University of Michigan researchers asked 295 patients receiving treatment at a mental health clinic whether they wanted to be more physically active and if exercise helped improve their mood and anxiety. They also asked if patients wanted their therapist to help them become more active.
Eighty-five percent said they wanted to exercise more and over 80 percent believed exercise helped improve their moods and anxiety much of the time. Almost half expressed interest in a one-time discussion, with many participants also wanting ongoing advice about physical activity with their mental health provider.
The study is now published in the journal General Hospital Psychiatry.
"Physical activity has been shown to be effective in alleviating mild to moderate depression and anxiety," said Carol Janney, lead author of the study and an MSU assistant professor of epidemiology. "Current physical activity guidelines advise at least 30 minutes, five days a week to promote mental and physical health, yet many of those surveyed weren't meeting these recommendations."
More than half of the participants said their mood limited their ability to exercise, which Janney said provides an opportunity for physicians and therapists in clinics to offer additional support.
"Offering physical activity programs inside the mental health clinics may be one of many patient-centered approaches that can improve the mental and physical health of patients," Janney said.
Marcia Valenstein, senior author and professor emeritus in psychiatry at U-M, agreed.
"Mental health treatment programs need to partner with fitness programs to support their patients' willingness to exercise more," she said. "This support might come from integrating personal trainers into mental health clinics or having strong partnerships with the YMCA or other community recreational facilities."
Both Valenstein and Janney said that psychiatrists and other providers might discuss with patients the general need to exercise, but few actually sit down with patients and create a comprehensive exercise plan for them or regularly make sure they are adhering to a specific goal.
"Mental health providers such as psychiatrists and therapists may not have the necessary training to prescribe physical activity as part of their mental health practice," Janney said. "But by teaming up with certified personal trainers or other exercise programs, it may help them prescribe or offer more recommendations for physical activity in the clinic setting."
Results also showed that over half of the patients surveyed showed interest in getting help from a personal trainer and were willing to pay a bit extra, but that the topic of physical activity was rarely discussed by their physician.
"This is a missed opportunity," Valenstein said. "If we can make it easier for both therapists and their patients to have easier access to physical activity services, then we are likely to help more patients reduce their depression and anxiety."
Once the effectiveness of this approach is proven, she added, health insurers might consider moving in the direction of covering services that help people exercise.
"Several insurers already do this for diabetes prevention, so it's not out of the question."
https://www.sciencedaily.com/releases/2017/11/171108151604.htm
Group exercise improves quality of life, reduces stress far more than individual work outs
October 30, 2017
Science Daily/American Osteopathic Association
Group exercise participants showed significant improvements in all three quality of life measures: mental (12.6 percent), physical (24.8 percent) and emotional (26 percent). They also reported a 26.2 percent reduction in perceived stress levels. By comparison, individual fitness participants on average worked out twice as long, and saw no significant changes in any measure, except in mental quality of life (11 percent increase).
Researchers found working out in a group lowers stress by 26 percent and significantly improves quality of life, while those who exercise individually put in more effort but experienced no significant changes in their stress level and a limited improvement to quality of life, according to a study published in The Journal of the American Osteopathic Association.
"The communal benefits of coming together with friends and colleagues, and doing something difficult, while encouraging one another, pays dividends beyond exercising alone," said Dayna Yorks, DO, lead researcher on this study. "The findings support the concept of a mental, physical and emotional approach to health that is necessary for student doctors and physicians."
Dr. Yorks and her fellow researchers at the University of New England College of Osteopathic Medicine recruited 69 medical students -- a group known for high levels of stress and self-reported low quality of life -- and allowed them to self-select into a twelve-week exercise program, either within a group setting or as individuals. A control group abstained from exercise other than walking or biking as a means of transportation.
Every four weeks, participants completed a survey asking them to rate their levels of perceived stress and quality of life in three categories: mental, physical and emotional.
Those participating in group exercise spent 30 minutes at least once a week in CXWORX, a core strengthening and functional fitness training program. At the end of the twelve weeks, their mean monthly survey scores showed significant improvements in all three quality of life measures: mental (12.6 percent), physical (24.8 percent) and emotional (26 percent). They also reported a 26.2 percent reduction in perceived stress levels.
By comparison, individual fitness participants were allowed to maintain any exercise regimen they preferred, which could include activities like running and weight lifting, but they had to work out alone or with no more than two partners. On average the solitary exercisers worked out twice as long, and saw no significant changes in any measure, except in mental quality of life (11 percent increase). Similarly, the control group saw no significant changes in quality of life or perceived stress.
"Medical schools understand their programs are demanding and stressful. Given this data on the positive impact group fitness can have, schools should consider offering group fitness opportunities," said Dr. Yorks. "Giving students an outlet to help them manage stress and feel better mentally and physically can potentially alleviate some of the burnout and anxiety in the profession."
https://www.sciencedaily.com/releases/2017/10/171030092917.htm
'Selfish brain' wins out when competing with muscle power
October 20, 2017
Science Daily/University of Cambridge
New research on our internal trade-off when physical and mental performance are put in direct competition has found that cognition takes less of a hit, suggesting more energy is diverted to the brain than body muscle. Researchers say the findings support the 'selfish brain' theory of human evolution.
Human brains are expensive -- metabolically speaking. It takes lot of energy to run our sophisticated grey matter, and that comes at an evolutionary cost.
Now, a new investigation into the immediate trade-off that occurs inside us when we have to think fast and work hard at the same time is the first to demonstrate that -- while both are impaired -- our mental ability is less affected than our physical capacity.
Researchers say that the findings suggest a "preferential allocation of glucose to the brain," which they argue is likely to be an evolved trait -- as prioritising quick thinking over fast moving, for example, may have helped our species survive and thrive.
Scientists from the University of Cambridge's PAVE (Phenotypic Adaptability, Variation and Evolution) research group tested 62 male students drawn from the University's elite rowing crews. The participants had an average age of 21.
The rowers performed two separate tasks: one memory, a three minute word recall test, and one physical, a three minute power test on a rowing machine.
They then performed both tasks at once, with individual scores compared to those from previous tests. As expected, the challenge of rowing and remembering at the same time reduced both physical and mental performance.
However, the research team found that change in recall was significantly less than the change in power output.
During the simultaneous challenge, recall fell by an average of 9.7%, while power fell by an average of 12.6%. Across all participants the drop in physical power was on average 29.8% greater than drop in cognitive function.
The team say the results of their new study, published today in the journal Scientific Reports, add evidence to the 'selfish brain' hypothesis: that the brain has evolved to prioritise its own energy needs over those of peripheral organs, such as skeletal muscle.
"A well-fuelled brain may have offered us better survival odds than well-fuelled muscles when facing an environmental challenge," said Dr Danny Longman, the study's lead author from the PAVE team in Cambridge's Department of Archaeology.
"The development of an enlarged and elaborated brain is considered a defining characteristic of human evolution, but one that has come as a result of trade-offs.
"At the evolutionary level, our brains have arguably cost us decreased investment in muscle as well as a shrunken digestive system.
"Developmentally, human babies have more stored fat than other mammals, acting as an energy buffer that feeds our high cerebral requirements.
"On an acute level, we have now demonstrated that when humans simultaneously experience extremes of physical and mental exertion, our internal trade-off preserves cognitive function as the body's priority."
The adult brain derives its energy almost exclusively from the metabolism of glucose. Yet skeletal muscle mass is also energetically expensive tissue, accounting for 20% of the human male 'basal metabolic rate' -- the energy used when doing nothing.
Longman says a limited supply of blood glucose and oxygen means that, when active, skeletal muscle becomes a "powerful competitor" to the brain. "This is the potential mechanism for the fast-acting trade-off in brain and muscle function we see in just a three minute window."
"Trade-offs between organs and tissues allow many organisms to endure conditions of energy deficit through internal prioritising. However, this comes at a cost," said Longman.
He points to examples of this trade-off in humans benefiting the brain. "The selfish nature of the brain has been observed in the unique preservation of brain mass as bodies waste away in people suffering from long-term malnutrition or starvation, as well as in children born with growth restriction."
Study details:
Protocol A -- isolated power test: Participants rowed at maximal effort for 3 minutes, and their average Wattage was recorded.
Protocol B -- isolated recall test: Participants performed a free recall word task in which they were shown 75 words from the Toronto Word Pool for a 3 minute period. They then had 5 minutes to recall and write as many words as possible. The number of words correctly recalled during a given time period was recorded.
Protocol C -- combined 'trade-off' test: Participants did both (but with a different word set), and their average Wattage and number of words correctly recalled was recorded. Researchers used 'paired samples t-tests' to compare power output between Protocols A and C, and for comparing free recall in Protocols B and C. They then compared the two differences, and found that the percentage change in free recall was significantly less than the percentage change in power output -- an average of 29.8%.
https://www.sciencedaily.com/releases/2017/10/171020092221.htm
Brain stimulation can improve athletic performance
Research into the effects of brain stimulation on athletes' performance has demonstrated that it is an effective way to improve endurance
October 12, 2017
Science Daily/University of Kent
Research into the effects of brain stimulation on athletes' performance has demonstrated that it is an effective way to improve endurance. The findings are expected to advance understanding of the brain's role in endurance exercise, how it can alter the physical limits of performance in healthy people and add evidence to the debate on the use of legal methods to enhance performance in competition.
The findings are expected to advance our understanding of the brain's role in endurance exercise, how it can alter the physical limits of performance in healthy people and add further evidence to the debate on the use of legal methods to enhance performance in competition.
The research, which was conducted by Dr Lex Mauger and colleagues at Kent's School of Sport and Exercise Sciences (SSES), set out to investigate how endurance limits are a matter for the mind as well as the body.
By testing cycling time to task failure (TTF) in a group of 12 active participants in a placebo controlled study, Dr Mauger discovered that stimulating the brain by passing a mild electrical current (transcranial direct current stimulation or tDCS) over the scalp to stimulate it increased the activity of the area associated with muscle contraction. This decreased perception of effort and increased the length of time participants could cycle for.
The team explained this is because the exercise felt less effortful following stimulation. tDCS has been used to enhance endurance performance but how it achieved this was previously unknown and this study has helped identify the mechanisms.
Bilateral extracephalic transcranial direct current stimulation improves endurance performance in healthy individuals (Dr Luca Angius, Dr Lex Mauger, Dr James Hopker, and Professor Samule Marcora, University of Kent, with Professor Alvaro Pascual-Leone, Berenson-Allen Center for Non-Invasive Brain Stimulation, Division of Cognitive Neurology, Beth Israel Deaconess Medical Center and Dr Emiliano Santarnecch, Harvard Medical School, Boston, MA, USA) is published in the journal Brain Stimulation.
https://www.sciencedaily.com/releases/2017/10/171012122736.htm
How sleep loss may contribute to adverse weight gain
August 23, 2018
Science Daily/Uppsala University
One night of sleep loss has a tissue-specific impact on the regulation of gene expression and metabolism in humans, according to researchers. This may explain how shift work and chronic sleep loss impairs our metabolism and adversely affects our body composition.
Epidemiological studies have shown that the risk for obesity and type 2 diabetes is elevated in those who suffer from chronic sleep loss or who carry out shift work. Other studies have shown an association between disrupted sleep and adverse weight gain, in which fat accumulation is increased at the same time as the muscle mass is reduced -- a combination that in and of itself has been associated with numerous adverse health consequences. Researchers from Uppsala and other groups have in earlier studies shown that metabolic functions that are regulated by e.g. skeletal muscle and adipose tissue are adversely affected by disrupted sleep and circadian rhythms. However, until now it has remained unknown whether sleep loss per se can cause molecular changes at the tissue level that can confer an increased risk of adverse weight gain.
In the new study, the researchers studied 15 healthy normal-weight individuals who participated in two in-lab sessions in which activity and meal patterns were highly standardised. In randomised order, the participants slept a normal night of sleep (over eight hours) during one session, and were instead kept awake the entire night during the other session. The morning after each night-time intervention, small tissue samples (biopsies) were taken from the participants' subcutaneous fat and skeletal muscle. These two tissues often exhibit disrupted metabolism in conditions such as obesity and diabetes. At the same time in the morning, blood samples were also taken to enable a comparison across tissue compartments of a number of metabolites. These metabolites comprise sugar molecules, as well as different fatty and amino acids.
The tissue samples were used for multiple molecular analyses, which first of all revealed that the sleep loss condition resulted in a tissue-specific change in DNA methylation, one form of mechanism that regulates gene expression. DNA methylation is a so-called epigenetic modification that is involved in regulating how the genes of each cell in the body are turned on or off, and is impacted by both hereditary as well as environmental factors, such as physical exercise.
"Our research group were the first to demonstrate that acute sleep loss in and of itself results in epigenetic changes in the so-called clock genes that within each tissue regulate its circadian rhythm. Our new findings indicate that sleep loss causes tissue-specific changes to the degree of DNA methylation in genes spread throughout the human genome. Our parallel analysis of both muscle and adipose tissue further enabled us to reveal that DNA methylation is not regulated similarly in these tissues in response to acute sleep loss," says Jonathan Cedernaes who led the study.
"It is interesting that we saw changes in DNA methylation only in adipose tissue, and specifically for genes that have also been shown to be altered at the DNA methylation level in metabolic conditions such as obesity and type 2 diabetes. Epigenetic modifications are thought to be able to confer a sort of metabolic "memory" that can regulate how metabolic programmes operate over longer time periods. We therefore think that the changes we have observed in our new study can constitute another piece of the puzzle of how chronic disruption of sleep and circadian rhythms may impact the risk of developing for example obesity," notes Jonathan Cedernaes.
Further analyses of e.g. gene and protein expression demonstrated that the response as a result of wakefulness differed between skeletal muscle and adipose tissue. The researchers say that the period of wakefulness simulates the overnight wakefulness period of many shift workers assigned to nightwork. A possible explanation for why the two tissues respond in the observed manner could be that overnight wakefulness periods exert a tissue-specific effect on tissues' circadian rhythm, resulting in misalignment between these rhythms. This is something that the researchers found preliminary support for also in this study, as well as in an earlier similar but smaller study.
"In the present study we observed molecular signatures of increased inflammation across tissues in response to sleep loss. However, we also saw specific molecular signatures that indicate that the adipose tissue is attempting to increase its capacity to store fat following sleep loss, whereas we instead observed signs indicating concomitant breakdown of skeletal muscle proteins in the skeletal muscle, in what's also known as catabolism. We also noted changes in skeletal muscle levels of proteins involved handling blood glucose, and this could help explain why the participants' glucose sensitivity was impaired following sleep loss. Taken together, these observations may provide at least partial mechanistic insight as to why chronic sleep loss and shift work can increase the risk of adverse weight gain as well as the risk of type 2 diabetes," says Jonathan Cedernaes.
The researchers have only studied the effect of one night of sleep loss, and therefore do not know how other forms of sleep or disruption of circadian misalignment would have affected the participants' tissue metabolism.
"It will be interesting to investigate to what extent one or more nights of recovery sleep can normalise the metabolic changes that we observe at the tissue level as a result of sleep loss. Diet and exercise are factors that can also alter DNA methylation, and these factors can thus possibly be used to counteract adverse metabolic effects of sleep loss," says Jonathan Cedernaes.
https://www.sciencedaily.com/releases/2018/08/180823095946.htm
Food for thought: How the brain reacts to food may be linked to overeating
July 19, 2018
Science Daily/Penn State
The reason why some people find it so hard to resist finishing an entire bag of chips or bowl of candy may lie with how their brain responds to food rewards, according to researchers who found that when certain regions of the brain reacted more strongly to being rewarded with food than being rewarded with money, those people were more likely to overeat.
In a study with children, researchers found that when certain regions of the brain reacted more strongly to being rewarded with food than being rewarded with money, those children were more likely to overeat, even when the child wasn't hungry and regardless of if they were overweight or not.
Shana Adise, a postdoctoral fellow at the University of Vermont who led the study while earning her doctorate at Penn State, said the results give insight into why some people may be more prone to overeating than others. The findings may also give clues on how to help prevent obesity at a younger age.
"If we can learn more about how the brain responds to food and how that relates to what you eat, maybe we can learn how to change those responses and behavior," Adise said. "This also makes children an interesting population to work with, because if we can stop overeating and obesity at an earlier age, that could be really beneficial."
Previous research on how the brain's response to food can contribute to overeating has been mixed. Some studies have linked overeating with brains that are more sensitive to food rewards, while others have found that being less sensitive to receiving food rewards makes you more likely to overeat.
Additionally, other studies have shown that people who are willing to work harder for food than other types of rewards, like money, are more likely to overeat and gain weight over time. But the current study is the first to show that children who have greater brain responses to food compared to money rewards are more likely to overeat when appealing foods are available.
"We know very little about the mechanisms that contribute to overeating," Adise said. "The scientific community has developed theories that may explain overeating, but whether or not they actually relate to food intake hadn't yet been evaluated. So we wanted to go into the lab and test whether a greater brain response to anticipating and winning food, compared to money, was related to overeating."
For the study, 59 children between the ages of 7 and 11 years old made four visits to the Penn State's Children's Eating Behavior Laboratory.
During the first three visits, the children were given meals designed to measure how they eat in a variety of different situations, such as a typical meal when they're hungry versus snacks when they're not hungry. How much the children ate at each meal was determined by weighing the plates before and after the meals.
On their fourth visit, the children had fMRI scans as they played several rounds of a game in which they guessed if a computer-generated number would be higher or lower than five. They were then told that if they were right, they would win either money, candy or a book, before it was revealed if they were correct or not.
The researchers found that when various regions of the brain reacted more to anticipating or winning food compared to money, those children were more likely to overeat.
"We also found that the brain's response to food compared to money was related to overeating regardless of how much the child weighed," Adise said. "Specifically, we saw that increased brain responses in areas of the brain related to cognitive control and self control when the children received food compared to money were associated with overeating."
Adise added that this is important because it suggests there may be a way to identify brain responses that can predict the development of obesity in the future.
Kathleen Keller, associate professor of nutritional sciences, Penn State, said the study -- recently published in the journal Appetite -- backs up the theory that an increased brain response in regions of the brain related to rewards is associated with eating more food in a variety of situations.
"We predicted that kids who had an increased response to food relative to money would be the ones to overeat, and that's what we ended up seeing," Keller said. "We specifically wanted to look at kids whose brains responded to one type of a reward over another. So it wasn't that they're overly sensitive to all rewards, but that they're highly sensitive to food rewards."
Keller said the findings give insight into how the brain influences eating, which is important because it could help identify children who are at risk for obesity or other poor eating habits before those habits actually develop.
"Until we know the root cause of overeating and other food-related behaviors, it's hard to give good advice on fixing those behaviors," Keller said. "Once patterns take over and you overeat for a long time, it becomes more difficult to break those habits. Ideally, we'd like to prevent them from becoming habits in the first place."
https://www.sciencedaily.com/releases/2018/07/180719085413.htm
Obesity + aging linked to Alzheimer's markers in the brain
Study finds most neurodegeneration in hippocampus of overweight, middle-age mice
June 28, 2018
Science Daily/American Physiological Society
A new study suggests that when a high-fat, high-sugar diet that leads to obesity is paired with normal aging, it may contribute to the development of Alzheimer's disease. In addition, researchers discovered that certain areas of the brain respond differently to risk factors associated with Alzheimer's.
Alzheimer's disease, the most common form of dementia, is a progressive brain disorder that leads to loss of cognitive skills and memory and causes significant changes in behavior. Aging is a significant risk factor for Alzheimer's. Previous studies suggest that diet-related obesity is also associated with development of the disease.
Researchers from Brock University in Ontario, Canada, looked at the effects of an obesity-inducing diet on insulin signaling (the process that tells the body how to use sugar), and markers of inflammation and cellular stress. These factors have been found to be involved in the progression of Alzheimer's disease during the aging process in mice. One group of mice received a high-fat, high-sugar diet ("HFS"), while the control group ate a normal diet. The researchers measured the animals' inflammation and stress levels in the hippocampus and the prefrontal cortex in the brain after 13 weeks on the assigned diets. They compared the brains of aged mice to those of a younger set of baseline mice. The hippocampus is near the center of the brain and is responsible for long-term memory. The prefrontal cortex, at the front of the brain, oversees complex cognitive, emotional and behavioral function.
Compared to the control group, the HFS group had significantly higher markers of inflammation, insulin resistance (altered insulin signaling) and cellular stress in areas of the hippocampus thought to be involved in the progression of Alzheimer's disease. The prefrontal cortex region of the HFS group showed more signs of insulin resistance, but inflammation and cellular stress markers did not change. The "region specific differences between the prefrontal cortex and hippocampus in response to aging with a HFS diet [indicates] that the disease pathology is not uniform throughout the brain," the researchers wrote.
The control group's inflammation levels were also increased after the trial when compared to the baseline readings. These results supports the theory that aging alone plays a role in the progression of Alzheimer's disease, and obesity exacerbates the effects of aging on brain function.
"This study provides novel information in relation to the mechanistic link between obesity and the transition from adulthood to middle age and signaling cascades that may be related to [Alzheimer's] pathology later in life," the research team wrote. "These results add to our basic understanding of the pathways involved in the early progression of [Alzheimer's] pathogenesis and demonstrate the negative effects of a HFS diet on both the prefrontal cortex and hippocampal regions."
https://www.sciencedaily.com/releases/2018/06/180628151649.htm
Adolescents who consume diet high in saturated fats may develop poor stress skills
Rat study provides insights into impact of diet on brain functioning during critical developmental period
June 13, 2018
Science Daily/Loma Linda University Adventist Health Sciences Center
Adolescents who consume a diet high in saturated fats may develop poor stress coping skills, signs of post-traumatic stress disorder as adults.
"The teen years are a very critical time for brain maturation, including how well (or not) we'll cope with stress as adults," said Dr. Johnny Figueroa, Assistant Professor, Division of Physiology, Department of Basic Sciences and Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine. "The findings of our research support that the lifestyle decisions made during adolescence -- even those as simple as your diet -- can make a big difference in our ability to overcome every day challenges."
The study, "Exposure to an obesogenic diet during adolescence leads to abnormal maturation of neural and behavioral substrates underpinning fear and anxiety," investigated the impact of an obesogenic Western-like high-saturated fat diet on the development of brain areas involved in responding to fear and stress. Study findings demonstrate that the consumption of an obesogenic diet during adolescence has a profound effect on phasic and sustained components of fear in the adult rat. Notably, the rats that consumed the high-saturated fat diet exhibited more anxiety, problems with associative and non-associative learning processes and an impaired fear-startle response.
Startle reflexes, which are studied in humans and lab animals, have a prominent role in anxiety and PTSD research. In this study, consumption of an obesogenic diet during adolescence reduced the extinction of fear memories -- a major impairment observed in people suffering from PTSD. In addition to not properly learning fear associations, the rats on the high-saturated fat diet incorrectly assessed the level of threat. This suggests that obesity and associated metabolic alterations may predispose individuals to PTSD-related psychopathology.
Researchers reported that the animals in the high-saturated fat diet group exhibited alterations in the structure of brain regions associated with PTSD, including the amygdala and the prefrontal cortex. Notably, the group found that the left-brain hemisphere seems to be more vulnerable to the effects of high-saturated fat diet consumption and obesity-related metabolic alterations. Understanding the neural networks that predispose obese adolescents to developing anxiety and stress-related disorders may help target metabolic measures to alleviate the burden of mental illness in this growing population.
Figueroa said the study leaves other questions open for further investigation, such as replicability in human subjects and if the alterations seen in the brain structures are permanent or whether the effects can be reversed. Study limitations include lack of clarity on how the high-saturated fat diet impacts the adult brain, and whether the effects of the obesogenic diet on the fear response are related to deficits in fear memory consolidation, retrieval and expression.
https://www.sciencedaily.com/releases/2018/06/180613113738.htm