Chapter 13. Memory, Learning, and Development
Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.
Learning a musical instrument as a child gives the brain a boost that lasts long into adult life, say scientists. Adults who used to play an instrument, even if they have not done so in decades, have a faster brain response to speech sounds, research suggests. The more years of practice during childhood, the faster the brain response was, the small study found. The Journal of Neuroscience work looked at 44 people in their 50s, 60s and 70s. The volunteers listened to a synthesised speech syllable, "da", while researchers measured electrical activity in the region of the brain that processes sound information - the auditory brainstem. Despite none of the study participants having played an instrument in nearly 40 years, those who completed between four and 14 years of music training early in life had a faster response to the speech sound than those who had never been taught music. Lifelong skill Researcher Michael Kilgard, of Northwestern University, said: "Being a millisecond faster may not seem like much, but the brain is very sensitive to timing and a millisecond compounded over millions of neurons can make a real difference in the lives of older adults." As people grow older, they often experience changes in the brain that compromise hearing. For instance, the brains of older adults show a slower response to fast-changing sounds, which is important for interpreting speech. Musical training may help offset this, according to Dr Kilgard's study. BBC © 2013
by Catherine de Lange Speak more than one language? Bravo! It seems that being bilingual helps delay the onset of several forms of dementia. Previous studies of people with Alzheimer's disease in Canada showed that those who are fluent in two languages begin to exhibit symptoms four to five years later than people who are monolingual. Thomas Bak at the University of Edinburgh, UK, wanted to know whether this was truly down to language, or whether education or immigration status might be driving the delay, since most bilingual people living in Toronto, where the first studies were conducted, tended to come from an immigrant background. He also wondered whether people suffering from other forms of dementia might experience similar benefits. He teamed up with Suvarna Alladi, a neurologist working on memory disorders at Nizam's Institute of Medical Sciences (NIMSH) in Hyderabad, India. "In India, bilingualism is part of everyday life," says Bak. The team compared the age that dementia symptoms appeared in some 650 people who visited the NIMSH over six years. About half spoke at least two languages. This group's symptoms started on average four and a half years later than those in people who were monolingual. "Incredibly the number of years in delay of symptom onset they reported in the Indian sample is identical to our findings," says Ellen Bialystok, at Toronto's York University, who conducted the original Canadian studies. What's more, the same pattern appeared in three different types of dementia: Alzheimer's, frontotemporal and vascular. The results also held true for a group of people who were illiterate, suggesting that the benefits of being bilingual don't depend on education. © Copyright Reed Business Information Ltd.
by Anil Ananthaswamy THE first clinical trial aimed at boosting social skills in people with autism using magnetic brain stimulation has been completed – and the results are encouraging. "As a first clinical trial, this is an excellent start," says Lindsay Oberman of the Beth Israel Deaconess Medical Centre in Boston, who was not part of the study. People diagnosed with autism spectrum disorder often find social interactions difficult. Previous studies have shown that a region of the brain called the dorsomedial prefrontal cortex (dmPFC) is underactive in people with autism. "It's also the part of the brain linked with understanding others' thoughts, beliefs and intentions," says Peter Enticott of Monash University in Melbourne, Australia. Enticott and his colleagues wondered whether boosting the activity of the dmPFC using repetitive transcranial magnetic stimulation (rTMS), which involves delivering brief but strong magnetic pulses through the scalp, could help individuals with autism deal with social situations. So the team carried out a randomised, double-blind clinical trial – the first of its kind – involving 28 adults diagnosed with either high-functioning autism or Asperger's syndrome. Some participants received 15 minutes of rTMS for 10 days, while others had none, but experienced all other aspects, such as having coils placed on their heads and being subjected to the same sounds and vibrations. © Copyright Reed Business Information Ltd.
Link ID: 18863 - Posted: 11.02.2013
A new report released today by the Institute of Medicine (IOM) may help dispel some common misconceptions about sport-related concussions in youth—for example, that wearing helmets can prevent them. First and foremost, however, it highlights the large gaps in knowledge that make it difficult for parents, coaches, and physicians to navigate decisions about prevention and treatment. The report also suggests where federal research agencies should focus their attention. The study, by a 17-member committee assembled by the Washington, D.C.-based IOM, which advises the government on health issues, comes amid growing concern about sports-related brain injuries. Although much of the attention has focused on adult professional athletes playing American football, health professionals have highlighted the need to understand risks among young athletes as well. To help clarify matters, a number of agencies, including the Centers for Disease Control and Prevention (CDC), the Department of Defense, and the Department of Education, asked IOM to conduct its study. The most glaring obstacle to understanding youth concussion at this point is a lack of data, the report finds. Most published research on sports-related concussions has been conducted in adults, and “there’s little-to-no information about concussions in youth,” particularly for ages 5 to 21, says panel member Susan Margulies, a bioengineer at the University of Pennsylvania. It’s dangerous to assume that findings in adults can be mapped onto children, she says, because of the changes that occur during brain development. “It’s possible that the threshold for injury might be different across different age ranges.” © 2013 American Association for the Advancement of Science
By Ajai Raj Football has become notorious for the degeneration it causes in players' brains. Now a preliminary study of soccer players has found that frequently hitting the ball with the head may adversely affect brain structure and cognition. The study imaged the brains of 37 amateur soccer players, 21 to 44 years old, and found that players who reported “heading the ball” more frequently had microstructural changes in the white matter of their brains similar to those observed in patients with traumatic brain injury. These players also performed poorly on cognitive tests, compared with players who reported heading the ball less. The study, published online in June in Radiology, found evidence of a threshold—1,800 headings—above which the effects on memory begin to manifest. Neuroradiologist Michael Lipton of the Albert Einstein College of Medicine of Yeshiva University, who led the study, says the findings may indicate that heading causes mild concussions, even when players do not show symptoms. The results are noteworthy but far from conclusive, comments Jonathan French, a neuropsychologist in the Sports Medicine Concussion Program at the University of Pittsburgh Medical Center, who was not involved in the study. “The majority of soccer players who are concussed don't have any functional problems in everyday life,” he says. The structural changes detected in the study, he points out, are "so microscopic that we don't know what they actually mean” for long-term function. Lipton agrees more work is needed to determine the significance of the brain changes, but he hopes to call attention to the potential risk because soccer is the most popular sport in the world. © 2013 Scientific American
A mother's level of education has strong implications for a child's development. Northwestern University researchers show in a new study that low maternal education is linked to a noisier nervous system in children, which could affect their learning. "You really can think of it as static on your radio that then will get in the way of hearing the announcer’s voice," says Nina Kraus, senior author of the study and researcher at the Auditory Neuroscience Laboratory at Northwestern University. The study, published in the Journal of Neuroscience, is part of a larger initiative working with children in public high schools in inner-city Chicago. The adolescents are tracked from ninth to 12th grade. An additional group of children in the gang-reduction zones of Los Angeles are also being tracked. Kraus and colleagues are more broadly looking at how music experience, through classroom group-based musical experience, could offset certain negative effects of poverty. But first, they wanted to see what biological effects poverty may have on the adolescents' brain. In this particular study, 66 children - a small sample - in Chicago participated. Those whose mothers had a "lower education" tended to have not graduated from high school. Kraus's study did not directly track income of families, but most children in the study qualified for free lunch (to be eligible, a family of four must have income of about $29,000 or less). Researchers found "children from lower-SES (socioeconomic status) backgrounds are exposed to less complex and linguistically rich input in addition to hearing fewer words per hour from their caregivers," according to the study. © 2012 Cable News Network
Early childhood poverty has been linked to smaller brain size by U.S. researchers who are pointing to the importance of nurturing from caregivers as a protective factor. Children exposed to poverty tend to have poorer cognitive outcomes and school performance. To learn more about the biology of how, researchers started tracking the emotional and brain development of 145 preschoolers in metropolitan St. Louis for 10 years. Household poverty was measured by the income-to-needs ratio. Children were assessed each year for thee to six years before they received an MRI and questionnaires. A parent and child were also observed during a lab task that required the child (age four to seven) to wait for eight minutes before opening a brightly wrapped gift within arm's reach while the parent filled in questionnaires. "These study findings demonstrated that exposure to poverty during early childhood is associated with smaller white matter, cortical grey matter, and hippocampal and amygdala volumes," Dr. Joan Luby of the psychiatry department at Washington University School of Medicine in St. Louis and her co-authors concluded in Monday's issue of the journal JAMA Pediatrics. The findings were consistent with an earlier study by the same team that suggested supportive parenting also plays an important role in the development of the hippocampus in childhood independent of income. The brain's hippocampus is important for learning and memory and how we respond to stress. In the study, the effects of poverty on hippocampal volume was influenced by caregiving support or hospitality in the brain's light and right hemispheres and stressful life events on the left. Caregiver education was not a significant mediator. © CBC 2013
By David Dobbs If you want a look at a high-profile field dealing with a lot of humbling snags, peer into #ASHG2013, the Twitter hashtag for last week’s meeting of the American Society of Human Genetics, held in Boston. You will see successes, to be sure: Geneticists are sequencing and analyzing genomes ever faster and more precisely. In the last year alone, the field has quintupled the rate at which it identifies genes for rare diseases. These advances are leading to treatments and cures for obscure illnesses that doctors could do nothing about only a few years ago, as well as genetic tests that allow prospective parents to bear healthy children instead of suffering miscarriage after miscarriage. But many of the tweets—or any frank geneticist—will also tell you stories of struggle and confusion: The current list of cancer-risk genes, the detection of which leads some people to have “real organs removed,” likely contains many false positives, even as standard diagnostic sequencing techniques are missing many disease-causing mutations. There’s a real possibility that the “majority of cancer predisposition genes in databases are wrong.” And a sharp team of geneticists just last week cleanly dismantled a hyped study from last year that claimed to find a genetic signature of autism clear enough to diagnose the risk of it in unborn children. This sample reads like an abstract of the entire field of genetics. In researching a book about genetics over the past four years, I’ve found a field that stands in a bizarre but lovely state of confusion—taken aback, but eager to advance; balanced tenuously between wild ambition and a deep but troubling humility. In the 13 years since the sequencing of the first human genome, the field has solved puzzles that 14 years ago seemed hopeless. Yet geneticists with any historical memory hold a painful awareness that their field has fallen short of the glory that seemed close at hand when Francis Collins, Craig Venter, and Bill Clinton announced their apparent triumph in June 2000. © 2013 The Slate Group, LLC
Keyword: Genes & Behavior
Link ID: 18846 - Posted: 10.29.2013
By Amanda Mascarelli, When my son was in preschool, I did what many parents of excessively energetic and impulsive preschoolers have surely done: I worried whether his behavior might be a sign of attention-deficit hyperactivity disorder (ADHD). Then I sought input from two pediatricians and a family therapist. The experts thought that his behavior was developmentally normal but said it was still too early to tell for sure. They offered some tips on managing his behavior and creating more structure at home. One pediatrician worked with my son on self-calming techniques such as breathing deeply and pushing on pressure points in his hands. He also suggested an herbal supplement, Valerian Super Calm, for him to take with meals and advised us on dietary adjustments such as increasing my son’s intake of fatty acids. Studies have shown that a combination of omega-3 (found in foods such as walnuts, flaxseed and salmon) and omega-6 fatty acids (from food oils such as canola and flax) can reduce hyperactivity and other ADHD symptoms in some children. In the couple of years since trying these techniques, my son has outgrown most of those worrisome behaviors. I had just about written off the possibility of ADHD until a few weeks ago, when his kindergarten teacher mentioned that she was going to keep an eye on him for possible attention issues. Hearing that left me worried and heavy-hearted. Why is it still so hard to diagnose ADHD? And why is there so much emotional baggage associated with treating it? There are no firm numbers for the number of children with ADHD in the United States. The Centers for Disease Control and Prevention estimates that 9 percent of U.S. children ages 5 to 17 had received diagnoses of ADHD as of 2009. © 1996-2013 The Washington Post
By James Gallagher Health and science reporter, BBC News A clearer picture of what causes Alzheimer's disease is emerging after the largest ever analysis of patients' DNA. A massive international collaboration has now doubled the number of genes linked to the dementia to 21. The findings, published in the journal Nature Genetics, indicate a strong role for the immune system. Alzheimer's Research UK said the findings could "significantly enhance" understanding of the disease. The number of people developing Alzheimer's is growing around the world as people live longer. However, major questions around what causes the dementia, how brain cells die, how to treat it or even diagnose it remain unanswered. "It is really difficult to treat a disease when you do not understand what causes it," one of the lead researchers, Prof Julie Williams from Cardiff University, said. Detective work The genetic code, the instructions for building and running the body, was scoured for clues. A group - involving nearly three quarters of the world's Alzheimer's geneticists from 145 academic institutions - looked at the DNA of 17,000 patients and 37,000 healthy people. They found versions of 21 genes, or sets of instructions, which made it more likely that a person would develop Alzheimer's disease. They do not guarantee Alzheimer's will develop, but they do make the disease more likely. By looking at the genes' function in the body, it allows researchers to figure out the processes going wrong in Alzheimer's disease. BBC © 2013
By Janet Davison, CBC News Jason Novick has seen the darkness that mental health disorders can create. The 27-year-old Toronto man has also seen how advocacy — by himself and by others — has been vital in helping him cope with bipolar disorder, general anxiety disorder, mania and depression, particular during the stressful transition from his teenage years to leaving home for post-secondary school. "Mental health awareness … is still an issue that’s largely misunderstood," he said in a recent interview. "There’s a lot of [post-secondary] administrative workers and professors and program co-ordinators and what have you who won’t know the first thing about such issues, so your best ally is probably going to be yourself a lot of the time." Another ally can also be a caring friend or family member who steps up to help others understand the larger situation. Novick remembers going with his mother to "set the record straight" with a college professor. They wanted to explain to the instructor that it was his mental health that was his problem, not any lack of interest in the course. "It was my mental health that was causing me to be so withdrawn, that was causing me to be so unmotivated. I was passionate about the subject, but I was not passionate about life and living." Novick, who says he contemplated suicide at one point and has been in closed hospital wards three times because of his disorders, is much more passionate about life and living now, particularly after having completed an inpatient program at the Centre for Addiction and Mental Health in Toronto. © CBC 2013
By Gary Stix The Obama administration’s neuroscience initiative highlights new technologies to better understand the workings of brain circuits on both a small and large scale. Various creatures, from roundworms to mice, will be centerpieces of that program because the human brain is too complex—and the ethical issues too intricate—to start analyzing the actual human organ in any meaningful way. But what if there were already a means to figure out how the brain wires itself up and, in turn, to use this knowledge to study what happens in various neurological disorders of early life? Reports in scientific journals have started to trickle in on the way stem cells can spontaneously organize themselves into complex brain tissue—what some researchers have dubbed mini-brains. Christopher A. Walsh, Bullard Professor of pediatrics and neurology at Harvard Medical School, talked to Scientific American about the importance of just such work for understanding brain development and neurological disease. (Also, check out the Perspective Walsh did for Science on this topic, along with Byoung-il Bae.) In order to be able to understand the way the brain solves this tremendously complex problem of wiring itself up, we need to be able to study it rigorously in the laboratory. We need some sort of model. We can’t just take humans and put them under the microscope, so we have to find some way of modeling the brain. The mouse has been tremendously useful for understanding brain wiring and how cells in the brain form. And the mouse will continue to be very useful. The mouse is particularly useful in studying cellular effects of particular genes, but, as we get smarter and smarter about what the problems are, we’re increasingly able to think, not about things that we share with mice, but the differences that distinguish us from mice. © 2013 Scientific American
When frogs croak, the fringe-lipped bat, Trachops cirrhosus, listens. The bats use the sounds to track and feed on amphibians and to share dining tips with neighbors. In a new study, Patricia Jones of the University of Texas at Austin and colleagues trained a few frog-eating bats to associate a cell phone ringtone with food. Some of the bats reliably got food when they heard the phone ring. Others did not. The bats that failed to get food using their own cues paid more attention to new ones that their fellow mammals shared. Social learning becomes much more important if a bat is unsuccessful at finding food, the scientists report October 22 in the Proceedings of the Royal Society B. Observing how bats forage alone and together may help scientists understand the way new hunting behaviors spread through animal populations. It may also give insight to animals’ potential for cultivating culture, the authors suggest. © Society for Science & the Public 2000 - 2013.
Keyword: Learning & Memory
Link ID: 18823 - Posted: 10.23.2013
Katherine Harmon Courage An infant's innate sense for numbers predicts how their mathematical aptitude will develop years later, a team of US researchers has found. Babies can spot if a set of objects increases or decreases in number — for instance, if the number of dots on a screen grows, even when dot size, colour and arrangement also change. But until recently, researchers could generally only determine the number sense of groups of babies, thus ruling out the ability to correlate this with later mathematics skills in individuals. In 2010, Elizabeth Brannon, a neuroscientist at Duke University in Durham, North Carolina, and her colleagues demonstrated that they could test and track infants' number sense over time1. To do this, six-month-old babies are presented with two screens. One shows a constant number of dots, such as eight, changing in appearance, and the other also shows changing dots but presents different numbers of them — eight sometimes and 16 other times, for instance. An infant who has a good primitive number sense will spend more time gazing at the screen that presents the changing number of dots. In the latest work, which is published in this week's Proceedings of the National Academy of Sciences2, Brannon's team took a group of 48 children who had been tested at six months of age and retested them three years later, using the same dot test but also other standard maths tests for preschoolers — including some that assessed the ability to count, to tell which of two numbers is larger and to do basic calculations. © 2013 Nature Publishing Group
By Scott Barry Kaufman One of the longest standing assumptions about the nature of human intelligence has just been seriously challenged. According to the traditional “investment” theory, intelligence can be classified into two main categories: fluid and crystallized. Differences in fluid intelligence are thought to reflect novel, on-the-spot reasoning, whereas differences in crystallized intelligence are thought to reflect previously acquired knowledge and skills. According to this theory, crystallized intelligence develops through the investment of fluid intelligence in a particular body of knowledge. As far as genetics is concerned, this story has a very clear prediction: In the general population– in which people differ in their educational experiences– the heritability of crystallized intelligence is expected to be lower than the heritability of fluid intelligence. This traditional theory assumes that fluid intelligence is heavily influenced by genes and relatively fixed, whereas crystallized intelligence is more heavily dependent on acquired skills and learning opportunities. But is this story really true? In a new study, Kees-Jan Kan and colleagues analyzed the results of 23 independent twin studies conducted with representative samples, yielding a total sample of 7,852 people. They investigated how heritability coefficients vary across specific cognitive abilities. Importantly, they assessed the “Cultural load” of various cognitive abilities by taking the average percentage of test items that were adjusted when the test was adapted for use in 13 different countries. © 2013 Scientific American
By MAGGIE KOERTH-BAKER Between the fall of 2011 and the spring of 2012, people across the United States suddenly found themselves unable to get their hands on A.D.H.D. medication. Low-dose generics were particularly in short supply. There were several factors contributing to the shortage, but the main cause was that supply was suddenly being outpaced by demand. The number of diagnoses of Attention Deficit Hyperactivity Disorder has ballooned over the past few decades. Before the early 1990s, fewer than 5 percent of school-age kids were thought to have A.D.H.D. Earlier this year, data from the Centers for Disease Control and Prevention showed that 11 percent of children ages 4 to 17 had at some point received the diagnosis — and that doesn’t even include first-time diagnoses in adults. (Full disclosure: I’m one of them.) That amounts to millions of extra people receiving regular doses of stimulant drugs to keep neurological symptoms in check. For a lot of us, the diagnosis and subsequent treatments — both behavioral and pharmaceutical — have proved helpful. But still: Where did we all come from? Were that many Americans always pathologically hyperactive and unable to focus, and only now are getting the treatment they need? Probably not. Of the 6.4 million kids who have been given diagnoses of A.D.H.D., a large percentage are unlikely to have any kind of physiological difference that would make them more distractible than the average non-A.D.H.D. kid. It’s also doubtful that biological or environmental changes are making physiological differences more prevalent. Instead, the rapid increase in people with A.D.H.D. probably has more to do with sociological factors — changes in the way we school our children, in the way we interact with doctors and in what we expect from our kids. © 2013 The New York Times Company
Research indicates that indeed Americans girls and boys are going through puberty earlier than ever, though the reasons are unclear. Many believe our widespread exposure to synthetic chemicals is at least partly to blame, but it’s hard to pinpoint exactly why our bodies react in certain ways to various environmental stimuli. Researchers first noticed the earlier onset of puberty in the late 1990s, and recent studies confirm the mysterious public health trend. A 2012 analysis by the U.S. Centers for Disease Control and Prevention (CDC) found that American girls exposed to high levels of common household chemicals had their first periods seven months earlier than those with lower exposures. “This study adds to the growing body of scientific research that exposure to environmental chemicals may be associated with early puberty,” says Danielle Buttke, a researcher at CDC and lead author on the study. Buttke found that the age when a girl has her first period (menarche) has fallen over the past century from an average of age 16-17 to age 12-13. Earlier puberty isn’t just for girls. In 2012 researchers from the American Academy of Pediatrics (AAP) surveyed data on 4,100 boys from 144 pediatric practices in 41 states and found a similar trend: American boys are reaching puberty six months to two years earlier than just a few decades ago. African-American boys are starting the earliest, at around age nine, while Caucasian and Hispanics start on average at age 10. One culprit could be rising obesity rates. Researchers believe that puberty (at least for girls) may be triggered in part by the body building up sufficient reserves of fat tissue, signaling fitness for reproductive capabilities. Clinical pediatrician Robert Lustig of Benioff Children’s Hospital in San Francisco reports that obese girls have higher levels of the hormone leptin which in and of itself can lead to early puberty while setting off a domino effect of more weight gain and faster overall physical maturation. © 2013 Scientific American,
by Tina Hesman Saey Sleep hoses garbage out of the brain, a study of mice finds. The trash, including pieces of proteins that cause Alzheimer’s disease, piles up while the rodents are awake. Sleep opens spigots that bathe the brain in fluids and wash away the potentially toxic buildup, researchers report in the Oct. 18 Science. The discovery may finally reveal why sleep seems mandatory for every animal. It may also shed new light on the causes of neurodegenerative disorders such as Alzheimer’s and Parkinson’s diseases. “It’s really an eye-opening and intriguing finding,” says Chiara Cirelli, a sleep researcher at the University of Wisconsin–Madison. The results have already led her and other sleep scientists to rethink some of their own findings. Although sleep requirements vary from individual to individual and across species, a complete lack of it is deadly. But no one knows why. One popular idea is that sleep severs weak connections between brain cells and strengthens more robust connections to solidify memories (SN Online: 4/2/09; SN Online: 6/23/11). But a good memory is not a biological imperative. “You don’t die from forgetting what you learned yesterday,” says Maiken Nedergaard, a neuroscientist at the University of Rochester Medical Center in New York who led the study. Researchers in Nedergaard’s lab stumbled upon sleep’s role in garbage clearance while studying a brain drainage system they described last year (SN: 9/22/12, p. 15). This service, called the glymphatic system, flushes fluid from the brain and spinal cord into the space between brain cells. Ultimately, the fluid and any debris it carries washes into the liver for disposal. © Society for Science & the Public 2000 - 2013
By Brian Palmer Myopia isn’t an infectious disease, but it has reached nearly epidemic proportions in parts of Asia. In Taiwan, for example, the percentage of 7-year-old children suffering from nearsightedness increased from 5.8 percent in 1983 to 21 percent in 2000. An incredible 81 percent of Taiwanese 15-year-olds are myopic. If you think that the consequences of myopia are limited to a lifetime of wearing spectacles—and, let’s be honest, small children look adorable in eyeglasses—you are mistaken. The prevalence of high myopia, an extreme form of the disorder, in Asia has more than doubled since the 1980s, and children who suffer myopia early in life are more likely to progress to high myopia. High myopia is a risk factor for such serious problems as retinal detachment, glaucoma, early-onset cataracts, and blindness. The explosion of myopia is a serious public health concern, and doctors have struggled to identify the source of the problem. Nearsightedness has a strong element of heritability, but the surge in cases shows that a child’s environment plays a significant role. A variety of risk factors has been linked to the disorder: frequent reading, participation in sports, television watching, protein intake, and depression. When each risk factor was isolated, however, its overall effect on myopia rates seemed to be fairly minimal. Researchers believe they are now closing in on a primary culprit: too much time indoors. In 2008 orthoptics professor Kathryn Rose found that only 3.3 percent of 6- and 7-year-olds of Chinese descent living in Sydney, Australia, suffered myopia, compared with 29.1 percent of those living in Singapore. The usual suspects, reading and time in front of an electronic screen, couldn’t account for the discrepancy. The Australian cohort read a few more books and spent slightly more time in front of the computer, but the Singaporean children watched a little more television. On the whole, the differences were small and probably canceled each other out. The most glaring difference between the groups was that the Australian kids spent 13.75 hours per week outdoors compared with a rather sad 3.05 hours for the children in Singapore. © 2013 The Slate Group, LLC.
By Christopher Wanjek and LiveScience Your liver could be "eating" your brain, new research suggests. People with extra abdominal fat are three times more likely than lean individuals to develop memory loss and dementia later in life, and now scientists say they may know why. It seems that the liver and the hippocampus (the memory center in the brain), share a craving for a certain protein called PPARalpha. The liver uses PPARalpha to burn belly fat; the hippocampus uses PPARalpha to process memory. In people with a large amount of belly fat, the liver needs to work overtime to metabolize the fat, and uses up all the PPARalpha — first depleting local stores and then raiding the rest of the body, including the brain, according to the new study. The process essentially starves the hippocampus of PPARalpha, thus hindering memory and learning, researchers at Rush University Medical Center in Chicago wrote in the study, published in the current issue of Cell Reports. Other news reports were incorrect in stating that the researchers established that obese individuals were 3.6 times more likely than lean individuals to develop dementia. That finding dates back to a 2008 study by researchers at the Kaiser Permanente Division of Research in Oakland, Calif. In another study, described in a 2010 article in the Annals of Neurology, researchers at Boston University School of Medicine found that the greater the amount of belly fat, the greater the brain shrinkage in old age. © 2013 Scientific American