Chapter 13. Memory, Learning, and Development
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by Jessica Griggs, San Diego Pregnant women may pass on the effects of stress to their fetus by way of bacterial changes in their vagina, suggests a study in mice. It may affect how well their baby's brain is equipped to deal with stress in adulthood. The bacteria in our body outnumber our own cells by about 10 to 1, with most of them found in our gut. Over the last few years, it has become clear that the bacterial ecosystem in our body – our microbiome – is essential for developing and maintaining a healthy immune system. Our gut bugs also help to prevent germs from invading our bodies, and help to absorb nutrients from food. A baby gets its first major dose of bacteria in life as it passes through its mother's birth canal. En route, the baby ingests the mother's vaginal microbes, which begin to colonise the newborn's gut. Chris Howerton, then at the University of Pennsylvania in Philadelphia, and his colleagues wanted to know if this initial population of bacteria is important in shaping a baby's neurological development, and whether that population is influenced by stress during pregnancy. The first step was to figure out what features of the mother's vaginal microbiome might be altered by stress, and then see if any of those changes were transmitted to the offspring's gut. © Copyright Reed Business Information Ltd
by Laura Sanders SAN DIEGO — Teenagers’ brains are wired to confront a threat instead of retreating, research presented November 10 at the annual Society for Neuroscience meeting suggests. The results may help explain why criminal activity peaks during adolescence. Kristina Caudle of Weill Cornell Medical College in New York City and colleagues tested the impulse control of 83 people between ages 6 and 29. In the experiment, participants were asked to press a button when a photo of a happy face quickly flashed before them. They were told not to press the button when a face had a threatening expression. When confronted with the threatening faces, people between the ages of 13 and 17 were more likely to impulsively push the button than children and adults were, the team found. Brain scans revealed that activity in an area called the orbital frontal cortex peaked in teens when they successfully avoided pushing the button, suggesting that this region curbs the impulse to react, Caudle said. It’s not clear why children don’t have the same impulsive reaction to threatening faces. More studies could determine how the relevant brain systems grow and change, Caudle said. © Society for Science & the Public 2000 - 2013.
by Laura Sanders SAN DIEGO — When stress during pregnancy disrupts a growing baby’s brain, blame bacteria. Microbes take part in an elaborate chain reaction, a new study finds: First, stress changes the populations of bacteria dwelling in a pregnant mouse’s vagina; those changes then affect which bacteria colonize a newborn pup’s gut; and the altered gut bacteria change the newborn’s brain. The research, presented at the annual Society for Neuroscience meeting, may help explain how a stressful environment early in life can make a person more susceptible to disorders such as autism or schizophrenia. The finding also highlights the important and still mysterious ways that the bacteria living in bodies can influence the brain. “This is really fascinating and promising work,” said neuroscientist Cory Burghy of the University of Wisconsin–Madison. “I am excited to take a look at how these systems interact in humans,” she said. Stress during pregnancy dramatically shifts the mix of bacteria that dwell in the vagina, Christopher Howerton of the University of Pennsylvania reported November 11. The alarming odor of foxes, loud noise, physical restraints and other stressful situations during a mouse’s pregnancy changed the composition of its vaginal bacteria, he and his colleagues found. The population of helpful Lactobacillus bacteria, for instance, decreased after stress. And because newborn mouse pups populate their guts with bacteria dwelling in their mother’s birth canal, microbes from mom colonize the baby’s gut. Mice born to moms with lower levels of Lactobacillus in the vagina had lower levels of Lactobacillus in their guts soon after they were born, the team reported. © Society for Science & the Public 2000 - 2013
Ed Yong Humanity's success depends on the ability of humans to copy, and build on, the works of their predecessors. Over time, human society has accumulated technologies, skills and knowledge beyond the scope of any single individual. Now, two teams of scientists have independently shown that the strength of this cumulative culture depends on the size and interconnectedness of social groups. Through laboratory experiments, they showed that complex cultural traditions — from making fishing nets to tying knots — last longer and improve faster at the hands of larger, more sociable groups. This helps to explain why some groups, such as Tasmanian aboriginals, lost many valuable skills and technologies as their populations shrank. “For producing fancy tools and complexity, it’s better to be social than smart,” says psychologist Joe Henrich of the University of British Columbia in Vancouver, Canada, the lead author of one of the two studies, published today in Proceedings of the Royal Society B1. “And things that make us social are going to make us seem smarter.” “There were some theoretical models to explain these phenomena but no one had done experiments,” says evolutionary biologist Maxime Derex of the University of Montpellier, France, who led the other study, published online today in Nature2. Derex’s team asked 366 male students to play a virtual game in which they gained points — and eventually money — by building either an arrowhead or a fishing net. The nets offered greater rewards, but were also harder to make. The students watched video demonstrations of the two tasks in groups of 2, 4, 8 or 16, before attempting the tasks individually. Their arrows and nets were tested in simulations and scored. After each trial, they could see how other group members fared, and watch a step-by-step procedure for any one of the designs. © 2013 Nature Publishing Group
By Melissa Hogenboom Science reporter, BBC News Changes to specific cells in the retina could help diagnose and track the progression of Alzheimer's disease, scientists say. A team found genetically engineered mice with Alzheimer's lost thickness in this layer of eye cells. As the retina is a direct extension of the brain, they say the loss of retinal neurons could be related to the loss of brain cells in Alzheimer's. The findings were revealed at the US Society for Neuroscience conference. The team believes this work could one day lead to opticians being able to detect Alzheimer's in a regular eye check, if they had the right tools. Alterations in the same retinal cells could also help detect glaucoma - which causes blindness - and is now also viewed as a neurodegenerative disease similar to Alzheimer's, the researchers report. Scott Turner, director of the memory disorders programme at Georgetown University Medical Center, said: "The retina is an extension of the brain so it makes sense to see if the same pathologic processes found in an Alzheimer's brain are also found in the eye." Dr Turner and colleagues looked at the thickness of the retina in an area that had not previously been investigated. This included the inner nuclear layer and the retinal ganglion cell layer. They found that a loss of thickness occurred only in mice with Alzheimer's. The retinal ganglion cell layer had almost halved in size and the inner nuclear layer had decreased by more than a third. BBC © 2013
Sedentary adults may improve their memory as soon as six weeks after taking up aerobic exercise, a small brain imaging study suggests. Cardiovascular fitness and cognitive performance such as attention seem to improve after six months or more of aerobic exercise in previous aging studies. Now researchers in Texas have found signs of increased regional blood flow in the brain of 37 sedentary adults with an average age of 64 who were randomized to physical training or a control group who had the training after a waiting period. They found a higher resting cerebral blood flow in the brain's anterior cingulate region in the physical training group compared with controls. The anterior cingulate region is associated with better memory functions. The size of this brain region was also larger in another study of "successful cognitive agers" over the age of 80 compared to middle-aged or elderly controls. "A relatively rapid health benefit across brain, memory and fitness in sedentary adults soon after starting to exercise, some gains starting as early as six weeks, could motivate adults to start exercising regularly," the study's lead author, Sandra Bond Champman of the Center for BrainHealth in Dallas and her co-authors concluded in Monday's issue of the journal Frontiers in Aging Neuroscience. "The current findings shed new light on ways exercise promotes cognitive/brain health in aging." The participants all had a physical exam and screening for dementia, early cognitive impairment, depression and IQ before the study began. A noninvasive type of MRI was used to measure brain blood flow before, half way through the 6-week training sessions and at 12 weeks. © CBC 2013
Keyword: Learning & Memory
Link ID: 18920 - Posted: 11.13.2013
SAN DIEGO, CALIFORNIA—Why do teens—especially adolescent males—commit crimes more frequently than adults? One explanation may be that as a group, teenagers react more impulsively to threatening situations than do children or adults, likely because their brains have to work harder to reign in their behavior, a research team reported here yesterday at the Society for Neuroscience meeting. Whether it's driving too fast on a slick road or experimenting with drugs, teenagers have a reputation for courting danger that is often attributed to immaturity or poor decision-making. If immaturity or lack of judgment were the only problem, however, one would expect that children, whose brains are at an even earlier stage of development, would have an equal or greater penchant for risk-taking, says Kristina Caudle, a neuroscientist at the Weill Cornell Medical College in New York City who led the study. But younger children tend to be more cautious than teenagers, suggesting that there is something unique about adolescent brain development that lures them to danger, she says. It's hard to generalize about teenage impulsivity, because some adolescents clearly have more self-control than many adults, says principal investigator B. J. Casey, a neuroscientist. Still, a growing body of evidence suggests that, in general, teens specifically struggle to keep their cool in social situations, she says. Because many crimes committed during adolescence involve emotionally fraught social situations, such as conflict, Caudle and colleagues decided to test whether teens perform badly on a common impulsivity task when faced with social cues of threat. They recruited 83 people, ranging in age from 6 to 29, to perform a simple "Go/No-Go" task, in which they watched a series of faces making neutral or threatening facial expressions flicker past on a computer screen. Each time the participants saw a neutral face, they were instructed to hit a button. They were also told to hold back from pressing the button when they saw a threatening face. As the participants performed the task, the researchers monitored their brain activity with functional magnetic resonance imaging. © 2013 American Association for the Advancement of Science.
Babies born to women who exercised during pregnancy have enhanced brain development compared with babies born to moms who didn’t exercise while they were pregnant, a new Canadian study suggests. The babies of 10 women who did as little as 20 minutes of moderate exercise three times a week during pregnancy showed more advanced brain activity when they were tested at eight to 12 days old than the babies of eight women who did not exercise during pregnancy, reported University of Montreal researcher David Ellemberg and his colleagues at the Neuroscience 2013 conference in San Diego on Sunday. “We are optimistic that this will encourage women to change their health habits, given that the simple act of exercising during pregnancy could make a difference for their child's future,” Ellemberg said in a statement. The women in the study were randomly assigned to an exercise group or a sedentary group at the beginning of their second trimester. Those in the exercise group had to spend at least 20 minutes three times a week doing exercise intense enough to lead to at least a slight shortness of breath. After their babies were born, the researchers tested them by placing a cap of electrodes on the babies' heads and then playing novel sounds while they slept. They measured the electrical response of the babies' brains to see how well they could distinguish between different sounds. The researchers found that the babies in the exercise group produced signals associated with more mature brains. The researchers said they plan to test the children’s cognitive, motor and language development at age one to see if there are lasting effects. © CBC 2013
Keyword: Development of the Brain
Link ID: 18916 - Posted: 11.12.2013
Jessica Wright A new test of mouse intelligence closely mimics the types of assays used with people and detects a subtle learning deficit reminiscent of one seen in teenagers with autism, according to findings presented Saturday at the2013 Society for Neuroscience annual meeting in San Diego. Another behavioral test, also presented Saturday, uncovers an unexpected social deficit in an autism mouse model. The test in the first study could be used to screen for drugs that improve cognitive deficits associated with autism, says Jill Silverman, a postdoctoral associate in Jacqueline Crawley’s lab at the University of California, Davis MIND Institute. Silverman presented the work at a poster session. To measure learning in mice, researchers typically place them in a water maze, or see if they learn to anticipate an electric shock. “But you don’t shock people or put them in a pool to swim,” notes Silverman. Silverman instead trained the mice in a human activity: using a touchscreen. In the most basic form of the test, the mice see two graphic images (such as a plane and a spider) and learn that they get “yummy” strawberry milkshake if they touch the spider, Silverman says. (She says she uses milkshakes because the mice work hard for them, even if they aren’t hungry.) BTBR mice, which have many autism-like features, learn to go for the spider just as readily as control mice do. So Silverman made things much more complicated. The complex test follows the logic of transitive properties. For example, if John is taller than Anne and Anne is taller than Jane, we are able to infer that John is taller than Jane. © Copyright 2013 Simons Foundation
Sarah DeWeerdt Parts of the brain that process vision and control movements are poorly connected in children with autism, according to results presented Saturday at the 2013 Society for Neuroscience annual meeting in San Diego. In addition to the social deficits that are a core feature of autism, children with the disorder often have clumsy movements. Studies have also found that people with autism have trouble imitating others. The new study uncovers patterns of brain activity suggesting all three of these deficits may be related. The researchers used functional magnetic resonance imaging (fMRI) to measure resting-state activation — brain activity that occurs while individuals are resting quietly in the scanner — in 45 children with autism and 45 controls. Parts of the brain that tend to activate and deactivate together during this procedure are said to be functionally connected. The researchers zeroed in on two sets of brain structures involved in motor activity. One of them, the ventral motor component, includes parts of the cortex, the thalamus and lobule 6 of the cerebellum. They also focused on three areas of the brain involved in visual processing. The most interesting is a region at the back of the brain responsible for complex interpretation of visual information. © Copyright 2013 Simons Foundation
by Sarah Zielinski If you put two birds together and gave them a problem, would they be any better at solving it than if they were alone? A study in Animal Behaviour of common mynas finds that not only are they no better at problem solving when in a pair than when on their own, the birds actually get a lot worse when put in a group. Andrea S. Griffin and her research team from the University of Newcastle in Callaghan, Australia, began by using dog food pellets as bait to capture common mynas (a.k.a. the Indian mynah, Acridotheres tristis) from around Newcastle. Then they gave each of the birds an innovation test, consisting of a box containing a couple of drawers and some Petri dishes. To get to the food hidden in spots in the box, the birds would have to get creative and figure out how to open one of the four containers by doing things like levering up a lid or pushing open a drawer. The scientists then ranked the birds by innovative ability before pairing them up. Half the pairs consisted of a high-innovation and a low-innovation myna, and the other half were pairs of medium-innovation birds. Then the pairs each received an innovation test similar to the one with boxes. Another experiment tested the birds in same-sex groups of five. On their own, 29 of 34 birds were able to access at least one container. But in pairs, only 15 of the 34 birds did so, and they took a lot longer. Performance dropped for both high- and medium-innovation birds, and it didn’t improve for the low-ranked ones, which had done so poorly the first time around that their results couldn’t get any worse. In groups of five, birds’ results fell even further: No mynas solved any of those tasks. © Society for Science & the Public 2000 - 2013
by Laura Sanders Neonatal intensive care units are crammed full of life-saving equipment and people. The technology that fills these bustling hubs is responsible for saving the lives of fragile young babies. That technology is also responsible for quite a bit of noise. In the NICU, monitors beep, incubators whir and nurses, doctors and family members talk. This racket isn’t just annoying: NICU noise often exceeds acceptable levels set by the American Academy of Pediatrics, a 2009 analysis found. To dampen the din, many hospitals are shifting away from open wards to private rooms for preemies. Sounds like a no-brainer, right? Fragile babies get their own sanctuaries where they can recover and grow in peace. But in a surprising twist, a new study finds that this peace and quiet may actually be bad for some babies. Well aware of the noise problem in the NICU ward, Roberta Pineda of Washington University School of Medicine in St. Louis and colleagues went into their study of 136 preterm babies expecting to see benefits in babies who stayed in private rooms. Instead, the researchers found the exact opposite. By the time they left the hospital, babies who stayed in private rooms had less mature brains than those who stayed in an open ward. And two years later, babies who had stayed in private rooms performed worse on language tests. The results were not what the team expected. “It was extremely surprising,” Pineda told me. The researchers believe that the noise abatement effort made things too quiet for these babies. As distressing data from Romanian orphanages highlights, babies need stimulation to thrive. Children who grew up essentially staring at white walls with little contact from caregivers develop serious brain and behavioral problems, heartbreaking results from the Bucharest Early Intervention Project show. Hearing language early in life, even before birth, might be a crucial step in learning to talk later. And babies tucked away in private rooms might be missing out on some good stimulation. © Society for Science & the Public 2000 - 2013
Stanley Rachman. “Will these hands ne'er be clean?” In Shakespeare's play Macbeth, Lady Macbeth helps to plot the brutal murder of King Duncan. Afterwards she feels tainted by Duncan's blood and insists that “all the perfumes of Arabia” could not sweeten her polluted hands. Baffled by her compulsive washing, her doctor is forced to admit: “This disease is beyond my practise.” In the 400 years since Macbeth was first performed, other doctors, psychiatrists, neuroscientists and clinical psychologists — myself included — have also found the problem beyond the reach of their own expertise. We see compulsive washing a lot, mostly as a symptom of obsessive–compulsive disorder (OCD), but also in people who have suffered a physical or emotional trauma, for example in women who have suffered sexual assault. The events trigger a deep-seated psychological, and ultimately biological, response. We know that the driving force of compulsive washing is a fear of contamination by dirt and germs. An obsessive fear of contact with sexual fluids, for example, can drive compulsive washing in OCD and force people to restrict sexual activity to a specific room in the house. Compulsive washing fails to relieve the anxiety. Most patients with OCD continue to feel contaminated despite vigorous attempts to clean themselves. Why does repeated washing fail? There is much debate at present about the direction that psychiatric medicine and research should take. We should not underestimate what we can continue to learn from the careful observation of patients. Such observations have led my colleagues and me to diagnose a new cause of OCD and other types of compulsive washing: mental contamination. © 2013 Nature Publishing Group
Kenneth S. Kosik Twenty years of research and more than US$1-billion worth of clinical trials have failed to yield an effective drug treatment for Alzheimer's disease. Most neuroscientists, clinicians and drug developers now agree that people at risk of the condition will probably need to receive medication before the onset of any cognitive symptoms. Yet a major stumbling block for early intervention is the absence of tools that can reveal the first expression of the insidious disease. So far, researchers have tended to focus on macroscopic changes associated with the disease, such as the build up of insoluble plaques of protein in certain areas of the brain, or on individual genes or molecular pathways that seem to be involved in disease progression. I contend that detecting the first disruptions to brain circuitry, and tracking the anatomical and physiological damage underlying the steady cognitive decline that is symptomatic of Alzheimer's, will require tools that operate at the 'mesoscopic' scale: techniques that probe the activity of thousands or millions of networked neurons. Although such tools are yet to be realized, several existing technologies indicate that they are within reach. Charted territory All the current approaches that are used to diagnose Alzheimer's are crude and unreliable. Take the classic biomarkers of the disease: a build up of plaques of the protein β-amyloid in a person's cerebral cortex, for instance, or elevated levels of the tau protein and dampened levels of β-amyloid in their cerebrospinal fluid. Although such markers are predictive of the disease, the interval between their appearance and the onset of cognitive problems is hugely variable, ranging from months to decades. © 2013 Nature Publishing Group
Helen Shen A mixture of excitement, hope and anxiety made for an electric atmosphere in the crowded hotel ballroom. On a Monday morning in early May, neuroscientists, physicists and engineers packed the room in Arlington, Virginia, to its 150-person capacity, while hundreds more followed by webcast. Only a month earlier, US President Barack Obama had unveiled the neuroscience equivalent of a Moon shot: a far-reaching programme that could rival Europe's 10-year, €1-billion (US$1.3-billion) Human Brain Project (see page 5). The US Brain Research Through Advancing Innovative Neurotechnologies (BRAIN) Initiative would develop a host of tools to study brain activity, the president promised, and lead to huge breakthroughs in understanding the mind. But Obama's vague announcement on 2 April had left out key details, such as what the initiative's specific goals would be and how it would be implemented. So at their first opportunity — a workshop convened on 6 May by the National Science Foundation (NSF) and the Kavli Foundation of Oxnard, California — researchers from across the neuroscience spectrum swarmed to fill in the blanks and advocate for their favourite causes. The result was chaotic, acknowledges Van Wedeen, a neurobiologist at Harvard Medical School in Boston, Massachusetts, and one of the workshop's organizers. Everyone was afraid of being left out of 'the next big thing' in neuroscience — even though no one knew exactly what that might be. “The belief is we're ready for a leap forward,” says Wedeen. “Which leap, and in which direction, is still being debated.” © 2013 Nature Publishing Group
M. Mitchell Waldrop Kwabena Boahen got his first computer in 1982, when he was a teenager living in Accra. “It was a really cool device,” he recalls. He just had to connect up a cassette player for storage and a television set for a monitor, and he could start writing programs. But Boahen wasn't so impressed when he found out how the guts of his computer worked. “I learned how the central processing unit is constantly shuffling data back and forth. And I thought to myself, 'Man! It really has to work like crazy!'” He instinctively felt that computers needed a little more 'Africa' in their design, “something more distributed, more fluid and less rigid”. Today, as a bioengineer at Stanford University in California, Boahen is among a small band of researchers trying to create this kind of computing by reverse-engineering the brain. The brain is remarkably energy efficient and can carry out computations that challenge the world's largest supercomputers, even though it relies on decidedly imperfect components: neurons that are a slow, variable, organic mess. Comprehending language, conducting abstract reasoning, controlling movement — the brain does all this and more in a package that is smaller than a shoebox, consumes less power than a household light bulb, and contains nothing remotely like a central processor. To achieve similar feats in silicon, researchers are building systems of non-digital chips that function as much as possible like networks of real neurons. Just a few years ago, Boahen completed a device called Neurogrid that emulates a million neurons — about as many as there are in a honeybee's brain. And now, after a quarter-century of development, applications for 'neuromorphic technology' are finally in sight. © 2013 Nature Publishing Group
Ewen Callaway Children with autism make less eye contact than others of the same age, an indicator that is used to diagnose the developmental disorder after the age of two years. But a paper published today in Nature1 reports that infants as young as two months can display signs of this condition, the earliest detection of autism symptoms yet. If the small study can be replicated in a larger population, it might provide a way of diagnosing autism in infants so that therapies can begin early, says Warren Jones, research director at the Marcus Autism Center in Atlanta, Georgia. Jones and colleague Ami Klin studied 110 infants from birth — 59 of whom had an increased risk of being diagnosed with autism because they had a sibling with the disorder, and 51 of whom were at lower risk. One in every 88 children has an autism spectrum disorder (ASD), according to the most recent survey by the US Centers for Disease Control and Prevention in Atlanta. At ten regular intervals over the course of two years, the researchers in the new study showed infants video images of their carers and used eye-tracking equipment and software to track where the babies gazed. “Babies come into the world with a lot of predispositions towards making eye contact,” says Jones. “Young babies look more at the eyes than at any part of the face, and they look more at the face than at any part of the body.” Twelve children from the high-risk group were diagnosed with an ASD — all but two of them boys — and one male from the low-risk group was similarly diagnosed. Between two and six months of age, these children tended to look at eyes less and less over time. However, when the study began, these infants tended to gaze at eyes just as often as children who would not later develop autism. © 2013 Nature Publishing Group
By PAM BELLUCK In a study published Wednesday, researchers using eye-tracking technology found that children who were found to have autism at age 3 looked less at people’s eyes when they were babies than children who did not develop autism. But contrary to what the researchers expected, the difference was not apparent at birth. It emerged in the next few months and autism experts said that might suggest a window during which the progression toward autism can be halted or slowed. The study, published online in the journal Nature, found that infants who later developed autism began spending less time looking at people’s eyes between 2 and 6 months of age and paid less attention to eyes as they grew older. By contrast, babies who did not develop autism looked increasingly at people’s eyes until about 9 months old, and then kept their attention to eyes fairly constant into toddlerhood. “This paper is a major leap forward,” said Dr. Lonnie Zwaigenbaum, a pediatrician and autism researcher at the University of Alberta, who was not involved in the study. “Documenting that there’s a developmental difference between 2 and 6 months is a major, major finding.” The authors, Warren R. Jones and Ami Klin, both of the Marcus Autism Center and Emory University, also found that babies who showed the steepest decline in looking at people’s eyes over time developed the most severe autism. “Kids whose eye fixation falls off most rapidly are the ones who later on are the most socially disabled and show the most symptoms,” said Dr. Jones, director of research at the autism center. “These are the earliest known signs of social disability, and they are associated with outcome and with symptom severity. Our ultimate goal is to translate this discovery into a tool for early identification” of children with autism. Copyright 2013 The New York Times Company
Link ID: 18889 - Posted: 11.07.2013
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.