Chapter 15. Language and Our Divided Brain
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Erin Allday When a person suddenly loses the ability to speak or to understand what others are saying, the hardships that cascade from that loss can be overwhelming - from the seemingly trite to the devastatingly depressing. What hit Derrick Wong, 49, hardest was losing the ability to tell a joke. Ralph Soriano, 56, hates taking his car to the mechanic, knowing he will barely understand what's being said. "Girls," said Luke Waterman, 30, with a sigh. Flirting used to come easy. All three men - actually a pretty happy, hopeful gang for the most part - are longtime members of a group therapy program at the Aphasia Center of California, an Oakland nonprofit that offers treatment and ongoing education to people who have suffered communication disorders as a result of stroke or other brain injury. The nonprofit specializes in long-term therapy, an area of aphasia treatment that has taken off in the past few years. For many decades, doctors and speech pathologists assumed that patients had a window of six months to a year to recover language skills lost to a brain injury. Now, anecdotal reports and clinical research suggest that the window is much wider, and may even stay open a lifetime. "There is evidence that people can improve and regain skills, even years after a stroke," said Blair Menn, a speech language pathologist at Kaiser Permanente Medical Center in Redwood City. © 2014 Hearst Communications, Inc.
By NICHOLAS BAKALAR Childhood treatment with human growth hormone is strongly associated with an increased risk for stroke in early adulthood, a new study has found. The study adds evidence to previous reports suggesting an increased cardiac and cerebrovascular risk in children treated with growth hormone. Researchers studied 6,874 children, average age 11, who were small for their age but otherwise generally healthy and were treated with growth hormone from 1985 to 1996. They followed them to an average age of 28. There were 11 strokes in the group, four of them fatal. The analysis found that this was more than twice as many strokes as would be expected in a population this size, a statistically significant difference. The results, published online in the journal Neurology, were particularly striking for hemorrhagic stroke, the type caused by a ruptured blood vessel — there were more than seven times as many as would be expected. The authors acknowledged that they were unable to take into account some risk factors for stroke, such as family history and smoking. “Subjects on growth hormones should not panic on reading these results,” said the senior author, Dr. Joël Coste, a professor of biostatistics and epidemiology at the Hôtel Dieu hospital in Paris. “The doctor prescribing the hormone or the family doctor should be consulted and will be able to inform and advise patients.” © 2014 The New York Times Company
By Meeri Kim From ultrasonic bat chirps to eerie whale songs, the animal kingdom is a noisy place. While some sounds might have meaning — typically something like “I'm a male, aren't I great?” — no other creatures have a true language except for us. Or do they? A new study on animal calls has found that the patterns of barks, whistles, and clicks from seven different species appear to be more complex than previously thought. The researchers used mathematical tests to see how well the sequences of sounds fit to models ranging in complexity. In fact, five species including the killer whale and free-tailed bat had communication behaviors that were definitively more language-like than random. The study was published online Wednesday in the Proceedings of the Royal Society B. “We're still a very, very long way from understanding this transition from animal communication to human language, and it's a huge mystery at the moment,” said study author and zoologist Arik Kershenbaum, who did the work at the National Institute for Mathematical and Biological Synthesis. “These types of mathematical analyses can give us some clues.” While the most complicated mathematical models come closer to our own speech patterns, the simple models — called Markov processes — are more random and have been historically thought to fit animal calls. “A Markov process is where you have a sequence of numbers or letters or notes, and the probability of any particular note depends only on the few notes that have come before,” said Kershenbaum. So the next note could depend on the last two or 10 notes before it, but there is a defined window of history that can be used to predict what happens next. “What makes human language special is that there's no finite limit as to what comes next,” he said.
By Jane C. Hu Last week, people around the world mourned the death of beloved actor and comedian Robin Williams. According to the Gorilla Foundation in Woodside, California, we were not the only primates mourning. A press release from the foundation announced that Koko the gorilla—the main subject of its research on ape language ability, capable in sign language and a celebrity in her own right—“was quiet and looked very thoughtful” when she heard about Williams’ death, and later became “somber” as the news sank in. Williams, described in the press release as one of Koko’s “closest friends,” spent an afternoon with the gorilla in 2001. The foundation released a video showing the two laughing and tickling one another. At one point, Koko lifts up Williams’ shirt to touch his bare chest. In another scene, Koko steals Williams’ glasses and wears them around her trailer. These clips resonated with people. In the days after Williams’ death, the video amassed more than 3 million views. Many viewers were charmed and touched to learn that a gorilla forged a bond with a celebrity in just an afternoon and, 13 years later, not only remembered him and understood the finality of his death, but grieved. The foundation hailed the relationship as a triumph over “interspecies boundaries,” and the story was covered in outlets from BuzzFeed to the New York Post to Slate. The story is a prime example of selective interpretation, a critique that has plagued ape language research since its first experiments. Was Koko really mourning Robin Williams? How much are we projecting ourselves onto her and what are we reading into her behaviors? Animals perceive the emotions of the humans around them, and the anecdotes in the release could easily be evidence that Koko was responding to the sadness she sensed in her human caregivers. © 2014 The Slate Group LLC.
By James Gallagher Health editor, BBC News website Stimulating the part of the brain which controls movement may improve recovery after a stroke, research suggests. Studies showed firing beams of light into the brains of mice led to the animals moving further and faster than those without the therapy. The research, published in Proceedings of the National Academy of Science, could help explain how the brain recovers and lead to new treatments. The Stroke Association said the findings were interesting. Strokes can affect memory, movement and the ability to communicate. Brain cells die when their supply of oxygen and sugars is cut off by a blood clot. Stroke care is focused on rapid treatment to minimise the damage, but some recovery is possible in the following months as the brain rewires itself. The team at Stanford University School of Medicine investigated whether brain stimulation aided recovery in animal experiments. They used a technique called optogenetics to stimulate just the neurons in the motor cortex - the part of the brain responsible for voluntary movements - following a stroke. After seven days of stimulation, mice were able to walk further down a rotating rod than mice which had not had brain stimulation. After 10 days they were also moving faster. The researchers believe the stimulation is affecting how the wiring of the brain changes after a stroke. They detected higher levels of chemicals linked to the formation of new connections between brain cells. Lead researcher Prof Gary Steinberg said it was a struggle to give people drugs to protect brain cells in time as the "time window is very short". BBC © 2014
Link ID: 19979 - Posted: 08.20.2014
|By Matthew H. Schneps “There are three types of mathematicians, those who can count and those who can’t.” Bad joke? You bet. But what makes this amusing is that the joke is triggered by our perception of a paradox, a breakdown in mathematical logic that activates regions of the brain located in the right prefrontal cortex. These regions are sensitive to the perception of causality and alert us to situations that are suspect or fishy — possible sources of danger where a situation just doesn’t seem to add up. Many of the famous etchings by the artist M.C. Escher activate a similar response because they depict scenes that violate causality. His famous “Waterfall” shows a water wheel powered by water pouring down from a wooden flume. The water turns the wheel, and is redirected uphill back to the mouth of the flume, where it can once again pour over the wheel, in an endless cycle. The drawing shows us a situation that violates pretty much every law of physics on the books, and our brain perceives this logical oddity as amusing — a visual joke. The trick that makes Escher’s drawings intriguing is a geometric construction psychologists refer to as an “impossible figure,” a line-form suggesting a three-dimensional object that could never exist in our experience. Psychologists, including a team led by Catya von Károlyi of the University of Wisconsin-Eau Claire, have used such figures to study human cognition. When the team asked people to pick out impossible figures from similarly drawn illustrations that did not violate causality, they were surprised to discover that some people were faster at this than others. And most surprising of all, among those who were the fastest were those with dyslexia. © 2014 Scientific American
By Victoria Gill Science reporter, BBC News Scientists in Brazil have managed to eavesdrop on underwater "turtle talk". Their recordings have revealed that, in the nesting season, river turtles appear to exchange information vocally - communicating with each other using at least six different sounds. This included chatter recorded between females and hatchlings. The researchers say this is the first record of parental care in turtles. It shows they could be vulnerable to the effects of noise pollution, they warn. The results, published recently in the Journal Herpetologica, include recordings of the strange turtle talk. They reveal that the animals may lead much more socially complex lives than previously thought. The team, including researchers from the Wildlife Conservation Society (WCS) and the National Institute of Amazonian Research carried out their study on the Rio Trombetas in the Amazon between 2009 and 2011. They used microphones and underwater hydrophones to record more than 250 individual sounds from the animals. The scientists then analysed these vocalisations and divided them into six different types, correlating each category with a specific behaviour. Dr Camila Ferrara, of the WCS Brazil programme, told BBC News: "The [exact] meanings aren't clear... but we think they're exchanging information. "We think sound helps the animals to synchronise their activities in the nesting season," she said. The noises the animals made were subtly different depending on their behaviour. For example, there was a specific sound when adults were migrating through the river, and another when they gathered in front of nesting beaches. There was a different sound again made by adults when they were waiting on the beaches for the arrival of their hatchlings. BBC © 2014
By Rebecca Boyle Like a dog wagging its tail in anticipation of treats to come, dolphins and belugas squeal with pleasure at the prospect of a fish snack, according to a new study. It’s the first direct demonstration of an excitement call in these animals, says Peter Madsen, a biologist at Aarhus University in Denmark who was not involved in the study. To hunt and communicate, dolphins and some whale species produce a symphony of clicks, whistles, squeaks, brays, and moans. Sam Ridgway, a longtime marine biologist with the U.S. Navy’s Marine Mammal Program, says he heard distinctive high-pitched squeals for the first time in May 1963 while training newly captured dolphins at the Navy’s facility in Point Mugu, California. “We were throwing fish in, and each time they would catch a fish, they would make this sound,” he says. He describes it as a high-pitched “eeee,” like a child squealing in delight. Ridgway and his collaborators didn’t think much of the sound until later in the 1960s, when dolphins trained to associate a whistle tone with a task or behavior also began making it. Trainers teach animals a task by rewarding them with a treat and coupling it with a special noise, like a click or a whistle. Eventually only the sound is used, letting the animal know it will get a treat later. The whistle was enough to provoke a victory squeal, Ridgway says. Meanwhile, beluga whales would squeal after diving more than 600 meters to switch off an underwater speaker broadcasting tones. “As soon as the tone went off, they would make this same sound,” Ridgway says, “despite the fact that they’re not going to get a reward for five minutes.” He also heard the squeal at marine parks in response to trainers’ whistles. © 2014 American Association for the Advancement of Science.
By NATALIE ANGIER SOUTH LUANGWA NATIONAL PARK, ZAMBIA — We saw the impala first, a young buck with a proud set of ridged and twisted horns, like helical rebar, bounding across the open plain at full, desperate gallop. But why? A moment later somebody in our vehicle gasped, and the answer became clear. Rising up behind the antelope, as though conjured on movie cue from the aubergine glow of the late afternoon, were six African wild dogs, running in single file. They moved with military grace and precision, their steps synchronized, their radio-dish ears cocked forward, their long, puppet-stick legs barely skimming the ground. Still, the impala had such a jump on them that the dogs couldn’t possibly catch up — could they? We gunned the engine and followed. The pace quickened. The dogs’ discipline held steady. They were closing the gap and oh, no, did I really want to watch the kill? To my embarrassed relief, the violence was taken off-screen, when prey and predators suddenly dashed up a hill and into obscuring bushes. By the time we reached the site, the dogs were well into their communal feast, their dark muzzles glazed with bright red blood, their white-tipped tails wagging in furious joy. “They are the most enthusiastic animals,” said Rosie Woodroffe of the Institute of Zoology in London, who has studied wild dogs for the last 20 years. “Other predators may be bigger and fiercer, but I would argue that there is nothing so enthusiastic as a wild dog,” she said. “They live the life domestic dogs wish they could live.” In 1997, while devising an action plan to help save the wild dog species, Lycaon pictus, Dr. Woodroffe felt anything but exuberant. Wild dogs were considered among the most endangered of Africa’s mammals; Dr. Woodroffe had yet to see one in the wild, and she feared she never would. © 2014 The New York Times Company
Ian Sample, science editor Stroke patients who took part in a small pilot study of a stem cell therapy have shown tentative signs of recovery six months after receiving the treatment. Doctors said the condition of all five patients had improved after the therapy, but that larger trials were needed to confirm whether the stem cells played any part in their progress. Scans of the patients' brains found that damage caused by the stroke had reduced over time, but similar improvements are often seen in stroke patients as part of the normal recovery process. At a six-month check-up, all of the patients fared better on standard measures of disability and impairment caused by stroke, but again their improvement may have happened with standard hospital care. The pilot study was designed to assess only the safety of the experimental therapy and with so few patients and no control group to compare them with, it is impossible to draw conclusions about the effectiveness of the treatment. Paul Bentley, a consultant neurologist at Imperial College London, said his group was applying for funding to run a more powerful randomised controlled trial on the therapy, which could see around 50 patients treated next year. "The improvements we saw in these patients are very encouraging, but it's too early to draw definitive conclusions about the effectiveness of the therapy," said Soma Banerjee, a lead author and consultant in stroke medicine at Imperial College Healthcare NHS Trust. "We need to do more tests to work out the best dose and timescale for treatment before starting larger trials." The five patients in the pilot study were treated within seven days of suffering a severe stroke. Each had a bone marrow sample taken, from which the scientists extracted stem cells that give rise to blood cells and blood vessel lining cells. These stem cells were infused into an artery that supplied blood to the brain. © 2014 Guardian News and Media Limited
By Victoria Gill Science reporter, BBC News Very mobile ears help many animals direct their attention to the rustle of a possible predator. But a study in horses suggests they also pay close attention to the direction another's ears are pointing in order to work out what they are thinking. Researchers from the University of Sussex say these swivelling ears have become a useful communication tool. Their findings are published in the journal Current Biology. The research team studies animal behaviour to build up a picture of how communication and social skills evolved. "We're interested in how [they] communicate," said lead researcher Jennifer Wathan. "And being sensitive to what another individual is thinking is a fundamental skill from which other [more complex] skills develop." Ms Wathan and her colleague Prof Karen McComb set up a behavioural experiment where 72 individual horses had to use visual cues from another horse in order to choose where to feed. They led each horse to a point where it had to select one of two buckets. On a wall behind this decision-making spot was a life-sized photograph of a horse's head facing either to left or right. In some of the trials, the horses ears or eyes were covered. Horse images used in a study of horse communication The ears have it: Horses in the test followed the gaze of another horse, and the direction its ears pointed If the ears and eyes of the horse in the picture were visible, the horses being tested would choose the bucket towards which its gaze - and its ears - were directed. If the horse in the picture had either its eyes or its ears covered, the horse being tested would just choose a feed bucket at random. Like many mammals that are hunted by predators, horses can rotate their ears through almost 180 degrees - but Ms Wathan said that in our "human-centric" view of the world, we had overlooked the importance of these very mobile ears in animal communication. BBC © 2014
By GREGORY HICKOK IN the early 19th century, a French neurophysiologist named Pierre Flourens conducted a series of innovative experiments. He successively removed larger and larger portions of brain tissue from a range of animals, including pigeons, chickens and frogs, and observed how their behavior was affected. His findings were clear and reasonably consistent. “One can remove,” he wrote in 1824, “from the front, or the back, or the top or the side, a certain portion of the cerebral lobes, without destroying their function.” For mental faculties to work properly, it seemed, just a “small part of the lobe” sufficed. Thus the foundation was laid for a popular myth: that we use only a small portion — 10 percent is the figure most often cited — of our brain. An early incarnation of the idea can be found in the work of another 19th-century scientist, Charles-Édouard Brown-Séquard, who in 1876 wrote of the powers of the human brain that “very few people develop very much, and perhaps nobody quite fully.” But Flourens was wrong, in part because his methods for assessing mental capacity were crude and his animal subjects were poor models for human brain function. Today the neuroscience community uniformly rejects the notion, as it has for decades, that our brain’s potential is largely untapped. The myth persists, however. The newly released movie “Lucy,” about a woman who acquires superhuman abilities by tapping the full potential of her brain, is only the latest and most prominent expression of this idea. Myths about the brain typically arise in this fashion: An intriguing experimental result generates a plausible if speculative interpretation (a small part of the lobe seems sufficient) that is later overextended or distorted (we use only 10 percent of our brain). The caricature ultimately infiltrates pop culture and takes on a life of its own, quite independent from the facts that spawned it. © 2014 The New York Times Company
Nishad Karim African penguins communicate feelings such as hunger, anger and loneliness through six distinctive vocal calls, according to scientists who have observed the birds' behaviour in captivity. The calls of the "jackass" penguin were identified by researchers at the University of Turin, Italy. Four are exclusive to adults and two are exclusive to juveniles and chicks. The study, led by Dr Livio Favaro, found that adult penguins produce distinctive short calls to express their isolation from groups or their mates, known as "contact" calls, or to show aggression during fights or confrontations, known as "agonistic" calls. They also observed an "ecstatic display song", sung by single birds during the mating season and the "mutual display song", a custom duet sung by nesting partners to each other. Juveniles and chicks produce calls relating to hunger. "There are two begging calls; the first one is where chicks utter 'begging peeps', short cheeps when they want food from adults, and the second one we've called 'begging moan', which is uttered by juveniles when they're out of the nest, but still need food from adults," said Favaro. The team made simultaneous video and audio recordings of 48 captive African penguins at the zoo Zoom Torino, over a 104 non-consecutive days. They then compared the audio recordings with the video footage of the birds' behaviour. Additional techniques, including visual inspection of spectrographs, produced statistical and quantifiable results. The research is published in the journal PLOS One. © 2014 Guardian News and Media Limited
By PAUL VITELLO The conventional wisdom among animal scientists in the 1950s was that birds were genetically programmed to sing, that monkeys made noise to vent their emotions, and that animal communication, in general, was less like human conversation than like a bodily function. Then Peter Marler, a British-born animal behaviorist, showed that certain songbirds not only learned their songs, but also learned to sing in a dialect peculiar to the region in which they were born. And that a vervet monkey made one noise to warn its troop of an approaching leopard, another to report the sighting of an eagle, and a third to alert the group to a python on the forest floor. These and other discoveries by Dr. Marler, who died July 5 in Winters, Calif., at 86, heralded a sea change in the study of animal intelligence. At a time when animal behavior was seen as a set of instinctive, almost robotic responses to environmental stimuli, he was one of the first scientists to embrace the possibility that some animals, like humans, were capable of learning and transmitting their knowledge to other members of their species. His hypothesis attracted a legion of new researchers in ethology, as animal behavior research is also known, and continues to influence thinking about cognition. Dr. Marler, who made his most enduring contributions in the field of birdsong, wrote more than a hundred papers during a long career that began at Cambridge University, where he received his Ph.D. in zoology in 1954 (the second of his two Ph.D.s.), and that took him around the world conducting field research while teaching at a succession of American universities. Dr. Marler taught at the University of California, Berkeley, from 1957 to 1966; at Rockefeller University in New York from 1966 to 1989; and at the University of California, Davis, where he led animal behavior research, from 1989 to 1994. He was an emeritus professor there at his death. © 2014 The New York Times Company
|By Nathan Collins Time, space and social relationships share a common language of distance: we speak of faraway places, close friends and the remote past. Maybe that is because all three share common patterns of brain activity, according to a January study in the Journal of Neuroscience. Curious to understand why the distance metaphor works across conceptual domains, Dartmouth College psychologists used functional MRI scans to analyze the brains of 15 people as they viewed pictures of household objects taken at near or far distances, looked at photographs of friends or acquaintances, and read phrases such as “in a few seconds” or “a year from now.” Patterns of activity in the right inferior parietal lobule, a region thought to handle distance information, robustly predicted whether a participant was thinking about near versus far in any of the categories—indicating that certain aspects of time, space and relationships are all processed in a similar way in the brain. The results, the researchers say, suggest that higher-order brain functions are organized more around computations such as near versus far than conceptual domains such as time or social relationships. © 2014 Scientific American
Link ID: 19860 - Posted: 07.21.2014
By Meeri Kim Babies start with simple vowel sounds — oohs and aahs. A mere months later, the cooing turns into babbling — “bababa” — showing off a newfound grasp of consonants. A new study has found that a key part of the brain involved in forming speech is firing away in babies as they listen to voices around them. This may represent a sort of mental rehearsal leading up to the true milestone that occurs after only a year of life: baby’s first words. Any parent knows how fast babies learn how to comprehend and use language. The skill develops so rapidly and seemingly without much effort, but how do they do it? Researchers at the University of Washington are a step closer to unraveling the mystery of how babies learn how to speak. They had a group of 7- and 11-month-old infants listen to a series of syllables while sitting in a brain scanner. Not only did the auditory areas of their brains light up as expected but so did a region crucial to forming higher-level speech, called Broca’s area. A year-old baby sits in a brain scanner, called magnetoencephalography -- a noninvasive approach to measuring brain activity. The baby listens to speech sounds like "da" and "ta" played over headphones while researchers record her brain responses. (Institute for Learning and Brain Sciences, University of Washington) These findings may suggest that even before babies utter their first words, they may be mentally exercising the pivotal parts of their brains in preparation. Study author and neuroscientist Patricia Kuhl says that her results reinforce the belief that talking and reading to babies from birth is beneficial for their language development, along with exaggerated speech and mouth movements (“Hiii cuuutie! How are youuuuu?”). © 1996-2014 The Washington Post
Some concussion symptoms that last three months after a head injury may be related to post-traumatic stress disorder, a new study suggests. Mild traumatic brain injury accounts for more than 90 per cent of brain injuries, according to an international review for the World Health Organization, but little is known about prognosis. TMR car accident Road crashes were the source of many of the head injuries suffered by patients in the study group. (Radio-Canada) In Wednesday’s issue of the journal JAMA Psychiatry, Emmanuel Lagarde of the University of Boredeaux, David Cassidy of Toronto Western Research Institute and their team focused on 534 patients with head injuries and 827 control patients with non-head injuries who went to an emergency department in France. Concussions or mild traumatic brain injury can lead to three different types of symptoms: During the three-month followup, 21 per cent of the patients with head injuries and 16 per cent of the patients with non-head injuries met the criteria for a diagnosis of post-concussion syndrome. Nearly nine per cent of patients with head injuries met the criteria for PTSD compared with two per cent of patients in the control group. In a statistical analysis, having a mild traumatic brain injury was a predicator of PTSD, but not post-concussion syndrome. "Available evidence does not support further use of post-concussion syndrome. Our results also stressed the importance of considering PTSD risk and treatment for patients with mild traumatic brain injury," the researchers concluded. Jane Topolovec-Vranic, a clinical researcher in mild traumatic brain injury and neuroscience at St. Michael’s Hospital in Toronto, said the study was well done with rigorous analyses and a control group that is often missing in such studies. © CBC 2014
|By Daisy Yuhas At Sunday’s World Cup Final, German soccer player Christoph Kramer knocked his head against an Argentine opponent’s shoulder with such force that Kramer spun to the ground and fell face down. The blow was one of many at this year’s competition, which further fueled a rising debate about concussion, the damages of fútbol versus football and the best response to head injuries. Part of the challenge in understanding these injuries is how varied they can be. Although much attention has gone to severe forms of traumatic brain injury (TBI) such as concussion-induced coma, far more common are the milder impacts that come from falling off a bicycle, a low-speed car accident or taking a weak punch in a fistfight. These injuries may not entail losing consciousness but rather just a brief lack in responsiveness before recovering. Now a group of researchers in the U.K. at Newcastle University, the University of Aberdeen and the University of Edinburgh have released results of a longer-term investigation of individuals who have suffered such first-time, minor head injuries. Their findings hint that the contusions leave a lasting trace in the brain. The team, led by Newcastle imaging physicist Andrew Blamire, scanned the brains of 53 individuals with mild or moderate TBI within two weeks of the injury. They mapped the tracts of fibers connecting brain regions in the patients as well as in 33 healthy subjects. Blamire and colleagues discovered distinct differences between the two groups. “Even in patients with mild injury, you can detect a marker of that injury,” Blamire says. That marker may distinguish mild injuries from more forceful impacts. In cases of severe TBI, brain tissue known as white matter that envelops the tracts deteriorates, effectively mashed by the impact. But Blamire identified an opposite trend in the mild and moderate cases. For these patients, the white matter fibers became even more structured. He and his colleagues hypothesize that this organization may be caused by an inflammatory response in which the brain’s glial cells leap into action, perhaps repairing damage or blocking further injury. © 2014 Scientific American
Keyword: Brain Injury/Concussion
Link ID: 19845 - Posted: 07.17.2014
By NICHOLAS BAKALAR The incidence of stroke in the United States has declined significantly over the past two decades, a new analysis has found. The decreases were apparent in people older than 65, the most common age group for stroke, and were similar in men and women and in blacks and whites. There were decreases in stroke deaths as well, but they were concentrated in younger research participants. The report appeared in JAMA. Researchers followed 14,357 people, ages 45 to 64 at the start of the study, from 1987 to 2011. After accounting for coronary heart disease, hypertension, diabetes, smoking, statin use and other factors, they found that the incidence of stroke decreased by about 50 percent over the period of the study, and stroke deaths by about 40 percent. Smoking cessation and better treatment of hypertension and high cholesterol accounted for part of the decrease, according to the senior author, Dr. Josef Coresh, a professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health, and improved medical care and more rigorous control of risk factors probably helped as well. Increased diabetes prevalence, on the other hand, contributed to higher risk. “The decrease in stroke also suggests that there’s a decrease in smaller strokes that we may not detect,” he said, “and that would bode well for overall brain health and the potential for decreasing the risk of dementia with aging.” © 2014 The New York Times Company
Link ID: 19839 - Posted: 07.16.2014
By Joel Achenbach Friends often look alike. The tendency of people to forge friendships with people of a similar appearance has been noted since the time of Plato. But now there is research suggesting that, to a striking degree, we tend to pick friends who are genetically similar to us in ways that go beyond superficial features. For example, you and your friends are likely to share certain genes associated with the sense of smell. Our friends are as similar to us genetically as you’d expect fourth cousins to be, according to the study published Monday in the Proceedings of the National Academy of Sciences. This means that the number of genetic markers shared by two friends is akin to what would be expected if they had the same great-great-great-grandparents. “Your friends don’t just resemble you superficially, they resemble you genetically,” said Nicholas A. Christakis, a physician and social scientist at Yale University and a co-author of the study. The resemblance is slight, just about 1 percent of the genetic markers, but that has huge implications for evolutionary theory, said James Fowler, a professor of medical genetics and political science at the University of California at San Diego. “We can do better than chance at predicting if two people are going to be friends if all we have is their genetic data,” Fowler said. This is a data-driven study that covers hundreds of friendship pairs and stranger pairs, plus hundreds of thousands of genetic markers. There’s no single “friendship” gene driving people together. There’s no way to say that a person befriended someone else because of any one genetic trait.