Chapter 15. Brain Asymmetry, Spatial Cognition, and Language
Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.
Perry Link People who study other cultures sometimes note that they benefit twice: first by learning about the other culture and second by realizing that certain assumptions of their own are arbitrary. In reading Colin McGinn’s fine recent piece, “Groping Toward the Mind,” in The New York Review, I was reminded of a question I had pondered in my 2013 book Anatomy of Chinese: whether some of the struggles in Western philosophy over the concept of mind—especially over what kind of “thing” it is—might be rooted in Western language. The puzzles are less puzzling in Chinese. Indo-European languages tend to prefer nouns, even when talking about things for which verbs might seem more appropriate. The English noun inflation, for example, refers to complex processes that were not a “thing” until language made them so. Things like inflation can even become animate, as when we say “we need to combat inflation” or “inflation is killing us at the check-out counter.” Modern cognitive linguists like George Lakoff at Berkeley call inflation an “ontological metaphor.” (The inflation example is Lakoff’s.) When I studied Chinese, though, I began to notice a preference for verbs. Modern Chinese does use ontological metaphors, such as fāzhăn (literally “emit and unfold”) to mean “development” or xὶnxīn (“believe mind”) for “confidence.” But these are modern words that derive from Western languages (mostly via Japanese) and carry a Western flavor with them. “I firmly believe that…” is a natural phrase in Chinese; you can also say “I have a lot of confidence that…” but the use of a noun in such a phrase is a borrowing from the West. © 1963-2016 NYREV, Inc
By Sheryl Ubelacker, The Canadian Press Posted: Peter Chaban was up early doing dishes one morning in 2012 when he noticed there was water flowing over his hand — but he couldn't feel it. Next thing he knew, he lost all sensation and strength on his left side and dropped to floor. Within seconds he was lying there completely immobilized. By the time the ambulance arrived at his vacation property near Collingwood, Ont., Chaban had recovered. But doctors at the local hospital diagnosed him with a probable transient ischemic attack, or TIA, a type of temporary stroke that leaves no permanent damage. Once he returned home to Toronto, Chaban was sent for an MRI, and the brain scan confirmed that diagnosis. But of more concern was the discovery of "quite a few" lesions in his brain, the result of "silent strokes" that show up as small holes on imaging. When the strokes had occurred and over what time period was a mystery to Chaban, who had experienced no symptoms. That's why, in fact, they're known as silent — patients have no idea they've had a miniature clot or microbleed in the brain that has destroyed a tiny chunk of neurons, but resulted in no loss of function as would typically occur with a full-blown stroke. "I was never aware of any deficits," said Chaban, 64, who retired from his research job at the Hospital for Sick Children three years ago. "When I was employed, I was quite cognitively active. "I was physically very active. I ski, play golf, I played squash until a few years ago. And my health is very good, so the silent strokes hadn't expressed themselves, at least to my awareness." ©2016 CBC/Radio-Canada.
Link ID: 23025 - Posted: 12.27.2016
As 2016 draws to a close, we are re-visiting some of the people we met this year — including one man who survived a stroke at a young age, and a listener who heard his story on the radio. DAVID GREENE, HOST: Now as 2016 draws to a close, we're revisiting some of the people we met this year. And NPR's Rae Ellen Bichell checks back with a man who survived a stroke in his 40s and also a listener who heard his story. RAE ELLEN BICHELL, BYLINE: Back in February, I reported a story about strokes increasing in adults under 50. Troy Hodge, a 43-year-old man living in Maryland, shared his story about having a stroke two years earlier. (SOUNDBITE OF ARCHIVED BROADCAST) TROY HODGE: I remember setting myself on the floor because I was really hot. And I wanted to get some water to splash on my face. BICHELL: When the story aired on MORNING EDITION, the radio waves carried Hodge's voice into the home of Sue Bryson, a teacher in Virginia. SUE BRYSON: It was just a normal Monday morning and I was just getting ready for work and I was listening to NPR. BICHELL: Listening to Hodge's story, Bryson realized that right then, she was having similar symptoms, that she was having a stroke. So she called her neighbors and they took her to the emergency room. BRYSON: I would have never gone to the hospital if I didn't hear your show - never. BICHELL: Bryson is now back in the classroom and Hodge has made some changes. He moved into a bigger apartment. He walks up a flight of stairs each day without his cane to check the mail. He sometimes forgets things. HODGE: Memory's not too bad, I mean, it's... © 2016 npr
Link ID: 23024 - Posted: 12.27.2016
By Veronique Greenwood Babies' ability to soak up language makes them the envy of adult learners everywhere. Still, some grown-ups can acquire new tongues with surprising ease. Now some studies suggest it is possible to predict a person's language-learning abilities from his or her brain structure or activity—results that may eventually be used to help even the most linguistically challenged succeed. In one study, published in 2015 in the Journal of Neurolinguistics, a team of researchers looked at the structure of neuron fibers in white matter in 22 beginning Mandarin students. Those who had more spatially aligned fibers in their right hemisphere had higher test scores after four weeks of classes, the scientists found. Like a freeway express lane, highly aligned fibers are thought to speed the transfer of information within the brain. Although language is traditionally associated with the left hemisphere, the right, which seems to be involved in pitch perception, may play a role in distinguishing the tones of Mandarin, speculates study author Zhenghan Qi of the Massachusetts Institute of Technology. Wired for Learning Your ability to learn a new language may be influenced by brain wiring. Diffusion tensor imaging of native English speakers learning Mandarin reveals that people who learn better have more aligned nerve fibers (shown with warmer colors) in two regions in the right hemisphere (A and B). In this case, subject 2, who has more aligned fibers, was a more successful learner than subject 1. © 2016 Scientific American
Link ID: 23019 - Posted: 12.26.2016
Lisa Vincenz-Donnelly A test that records the way the brain processes sound might provide a simple and reliable measure of concussion, a small study suggests. If the method works, it could help scientists work out how best to treat the poorly understood brain injury. In a paper published on 22 December in Scientific Reports1, neuroscientist Nina Kraus of Northwestern University in Evanston, Illinois, and other researchers say that they have found that a particular signal in neural activity, recorded with electrodes placed on the head as children listen to 'da' sounds from a speech synthesizer, can objectively demarcate concussed children from a healthy control group. The research was done on just 40 people — a tiny group — and will have to be repeated in larger samples. But other researchers are still excited by the report, because concussion is hard to diagnose, particularly in children. The study “may for the first time offer a simple and objective biomarker to measure the severity of brain injuries”, says Thomas Wisniewski, a neurologist at New York University’s Langone Medical Center. There is intense interest in finding a clear-cut biological signature for concussion, he says. “We have been crying out for a reliable method." Millions of people enter hospitals every year with blows to the head, and some of have concussion, a minor brain injury that can betoken more serious damage. To diagnose it, physicians rely on subjective complaints of dizziness, coordination tests and sometimes more involved procedures, such as magnetic resonance imaging (MRI) or computed tomography (CT) scans. But there’s no single objective way to detect concussion and measure its severity — and no simple test that can be administered regularly to determine when someone has recovered, a particularly important issue for athletes keen to be allowed back on the field. © 2016 Macmillan Publishers Limited
Jon Hamilton For patients with serious brain injuries, there's a strong link between sleep patterns and recovery. A study of 30 patients hospitalized for moderate to severe traumatic brain injuries found that sleep quality and brain function improved in tandem, researchers reported Wednesday in the journal Neurology. Patients who still had low levels of consciousness and cognitive functioning would "sleep for a couple of minutes and then wake up for a couple of minutes," both day and night, says Nadia Gosselin, the study's senior author and an assistant professor in the psychology department at the University of Montreal. But "when the brain recovered, the [normal] sleep-wake cycle reappeared," Gosselin says. The results raise the possibility that patients with brain injuries might recover more quickly if hospitals took steps to restore normal sleep patterns, Gosselin says. Drugs are one option, she says. Another is making sure patients are exposed to sunlight or its equivalent during the day and at night rest in a dark, quiet environment. "I think bad sleep can have bad consequences for brain recovery," she says. The findings are consistent with other research showing that "sleep is essential to restore body and brain functions," according to an editorial accompanying the study. The editorial was written by Andrea Soddu of the University of Western Ontario, and Claudio Bassetti of University Hospital Inselspital Bern in Switzerland. © 2016 npr
Ramin Skibba The high-pitched squeals of the humble bat may be as complex as the calls of dolphins and monkeys, researchers have found. A study published on 22 December in Scientific Reports1 reveals that the fruit bat is one of only a few animals known to direct its calls at specific individuals in a colony, and suggests that information in the calls of many social animals may be more detailed than was previously thought. Bats are noisy creatures, especially in their crowded caves, where they make calls to their neighbours. “If you go into a fruit-bat cave, you hear a cacophony,” says Yossi Yovel, a neuroecologist at Tel Aviv University in Israel who led the study. Until now, it has been difficult to separate this noise into distinct sounds, or to determine what prompted the individual to make a particular call. “Animals make sounds for a reason,” says Whitlow Au, a marine-bioacoustics scientist at the University of Hawaii at Manoa. “Most of the time, we don’t quite understand those reasons.” To find out what bats are talking about, Yovel and his colleagues monitored 22 captive Egyptian fruit bats (Rousettus aegyptiacus) around the clock for 75 days. They modified a voice-recognition program to analyse approximately 15,000 vocalizations collected during this time. The program was able to tie specific sounds to different social interactions captured by video, such as when two bats fought over food. © 2016 Macmillan Publishers
By Vik Adhopia, CBC News Every eight minutes someone in Canada has a stroke. But the odds of survival are getting better because of a new emergency intervention being offered at 22 hospitals across Canada. Spencer Higdon, 63, successfully received the procedure at Toronto Western Hospital in April after suddenly collapsing in his bathroom. "I was stepping into the shower and I dropped like a tonne of bricks." he said. When he regained consciousness he knew he'd had a stroke. "I couldn't move my right leg, my right arm, I couldn't speak, and I had difficulty moving my head." Physicians confirmed he'd had an ischemic stroke — a blood clot in his brain. Unless the blockage was cleared within a few hours, his paralysis would likely be permanent, or worse, he'd die. Higdon later learned from one of the treating physicians that because of the position of the clot in the brainstem, the consequences of his stroke could have been devastating. "She said it's called 'locked-in syndrome,' where your brain works just fine but nothing else in your body moves. You're lying in a bed and the only way to communicate is through your eyes. And that just horrified me." The procedure used to remove Higdon's clot, known as a thrombectomy, involves feeding a tiny catheter into an artery near the groin, all the way up into the brain and through the blockage. The device is expanded to grab the clot. Then it's pulled out, allowing the blood to flow again. Advanced imaging equipment helps navigate the catheter. For Higdon, the entire procedure took eight minutes, a record for the stroke team at Toronto Western. ©2016 CBC/Radio-Canada.
Link ID: 22999 - Posted: 12.20.2016
By Veronique Greenwood Baffling grammar, strange vowels, quirky idioms and so many new words—all of this makes learning a new language hard work. Luckily, researchers have discovered a number of helpful tricks, ranging from exposing your ears to a variety of native speakers to going to sleep soon after a practice session. A pair of recent papers suggests that even when you are not actively studying, what you hear can affect your learning and that sometimes listening without speaking works best. In one study, published in 2015 in the Journal of the Acoustical Society of America, linguists found that people who took breaks from learning new sounds performed just as well as those who took no breaks, as long as the sounds continued to play in the background. The researchers trained two groups of people to distinguish among trios of similar sounds—for instance, Hindi has “p,” “b” and a third sound English speakers mistake for “b.” One group practiced telling these apart one hour a day for two days. Another group alternated between 10 minutes of the task and 10 minutes of a “distractor” task that involved matching symbols on a worksheet while the sounds continued to play in the background. Remarkably, the group that switched between tasks improved just as much as the one that focused on the distinguishing task the entire time. “There's something about our brains that makes it possible to take advantage of the things you've already paid attention to and to keep paying attention to them,” even when you are focused on something else, suggests Melissa Baese-Berk, a linguist at the University of Oregon and a co-author of the study. In a 2016 study published in the Journal of Memory and Language, Baese-Berk and another colleague found that it is better to listen to new sounds silently rather than practice saying them yourself at the same time. Spanish speakers learning to distinguish among sounds in the Basque language performed more poorly when they were asked to repeat one of the sounds during training. The findings square with what many teachers have intuited—that a combination of focused practice and passive exposure to a language is the best approach. “You need to come to class and pay attention,” Baese-Berk says, “but when you go home, turn on the TV or turn on the radio in that language while you're cooking dinner, and even if you're not paying total attention to it, it's going to help you.” © 2016 Scientific American
Carl Zimmer Primates are unquestionably clever: Monkeys can learn how to use money, and chimpanzees have a knack for game theory. But no one has ever taught a nonhuman primate to say “hello.” Scientists have long been intrigued by the failure of primates to talk like us. Understanding the reasons may offer clues to how our own ancestors evolved full-blown speech, one of our most powerful adaptations. On Friday, a team of researchers reported that monkeys have a vocal tract capable of human speech. They argue that other primates can’t talk because they lack the right wiring in their brains. “A monkey’s vocal tract would be perfectly adequate to produce hundreds, thousands of words,” said W. Tecumseh Fitch, a cognitive scientist at the University of Vienna and a co-author of the new study. Human speech results from a complicated choreography of flowing air and contracting muscles. To make a particular sound, we have to give the vocal tract a particular shape. The vocal tracts of other primates contain the same elements as ours — from vocal cords to tongues to lips — but their geometry is different. That difference long ago set scientists to debating whether primates could make speechlike sounds. In the 1960s, Philip H. Lieberman, now a professor emeritus of Brown University, and his colleagues went so far as to pack a dead monkey’s vocal tract with plaster to get a three-dimensional rendering. © 2016 The New York Times Company
By Michael Price The famed parrot Alex had a vocabulary of more than 100 words. Kosik the elephant learned to “speak” a bit of Korean by using the tip of his trunk the way people whistle with their fingers. So it’s puzzling that our closest primate cousins are limited to hoots, coos, and grunts. For decades, monkeys’ and apes’ vocal anatomy has been blamed for their inability to reproduce human speech sounds, but a new study suggests macaque monkeys—and by extension, other primates—could indeed talk if they only possessed the brain wiring to do so. The findings might provide new clues to anthropologists and language researchers looking to pin down when humans learned to speak. “This certainly shows that the macaque vocal tract is capable of a lot more than has previously been assumed,” says John Esling, a linguist and phonetics expert at the University of Victoria in Canada, who was not involved with the work. The study’s lead author, William Tecumseh Sherman Fitch III, an evolutionary biologist and cognitive scientist at the University of Vienna, says the question of why monkeys and apes can’t speak goes back to Darwin. (Yes, Fitch is the great-great-great-grandson of U.S. Civil War General William Tecumseh Sherman.) Darwin thought nonhuman primates couldn’t talk because they didn’t have the brains, he says. But over time, anthropologists instead embraced the idea that the primates’ vocal tracts were holding them back: They simply lacked the flexibility to produce the wide range of vowels present in human speech. That remains the “textbook answer” today, Fitch says. © 2016 American Association for the Advancement of Science.
Men and women who suffered traumatic brain injuries had more than twice the risk of winding up in a federal prison in Canada as their uninjured peers, a new study shows. That doesn't surprise Dr. Geoffrey Manley, a neurosurgeon who runs a trauma centre. He knows all too well the long-term struggles of survivors of traumatic brain injuries. "Because there's no system of care for these individuals, they fall into the cracks and get themselves in trouble. And we really as a society are not doing a good job of taking care of people with traumatic brain injuries," Manley, who was not involved in the study, said in a phone interview. For 13 years, researchers followed more than 1.4 million people who were eligible for health care in Ontario and were between the ages of 18 and 28 in 1997. As reported in CMAJ Open, the open-access journal of the Canadian Medical Association, the research team linked subjects' health records to correctional records, adjusted for a variety of factors like age and substance abuse, and found that men with traumatic brain injuries were 2.5 times more likely to serve time in a Canadian federal prison than men without head injuries. Female prisoners were even more likely to have survived traumatic brain injuries. For women with these injuries, the risk of winding up in a Canadian federal prison was 2.76 times higher than it was for uninjured women, although the authors caution that the pool of incarcerated females was small, accounting for only 210 of the more than 700,000 women studied. ©2016 CBC/Radio-Canada.
Gabrielle Emanuel Megan Lordos, a middle school teacher, says she was not allowed to use the word "dyslexia." She's not alone. Parents and teachers across the country have raised concerns about some schools hesitating, or completely refusing, to say the word. As the most common learning disability in the U.S., dyslexia affects somewhere between 5 and 17 percent of the population. That means millions of school children around the country struggle with it. Under the Individuals with Disabilities Education Act (IDEA), schools are required to provide special services to help these students — things like reading tutors and books on tape. But those special services can be expensive, and many schools don't have the resources to provide these accommodations. That has led some parents and advocates to worry that some schools are making a careful calculation: If they don't acknowledge the issue — or don't use the word "dyslexia" — then they are not obligated to provide services. Last year, when Lordos was teaching English at a public school in Arlington, Va., she recalls a parent-teacher meeting in the conference room. Things started smoothly. Lordos says two parents had come in to talk with teachers and administrators about their son – Lordos' student, an eighth-grader – who was struggling to read. Partway through the meeting, Lordos says she suggested that the student might have orthographic dyslexia. Two of Lordos' own children have dyslexia and, she says, she noticed her student had similar challenges to the ones she'd seen at home. © 2016 npr
Link ID: 22949 - Posted: 12.05.2016
By Alice Klein It’s something all whale-watchers yearn to see. The sight of whales breaking the surface and slapping their fins on the water is a true spectacle – but the animals don’t do it just for show. Instead, it appears that all that splashing is about messaging other whales, and the big splashes are for long-distance calls. Ailbhe Kavanagh at the University of Queensland in Gatton, Australia, and her colleagues studied 94 different groups of humpback whales migrating south along the Queensland coast in 2010 and 2011. Humpback whales regularly leap out of the water and twist on to their backs – an action known as breaching – and slap their tails and fins in a repetitive fashion. The resulting sounds travel underwater and could possibly communicate messages to other whales. Drowning in sound: The sad case of the baby beluga whales The team found evidence for this idea. The animals were significantly more likely to breach when the nearest other whale group was more than 4 kilometres away, suggesting that the body-slapping sound of breaching was used to signal to distant groups. In contrast, repetitive tail and pectoral-fin slapping appeared to be for close-range communication. There was a sudden increase in this behaviour just before new whales joined or the group split up. © Copyright Reed Business Information Ltd.
Anya Kamenetz Brains, brains, brains. One thing we've learned at NPR Ed is that people are fascinated by brain research. And yet it can be hard to point to places where our education system is really making use of the latest neuroscience findings. But there is one happy nexus where research is meeting practice: bilingual education. "In the last 20 years or so, there's been a virtual explosion of research on bilingualism," says Judith Kroll, a professor at the University of California, Riverside. Again and again, researchers have found, "bilingualism is an experience that shapes our brain for a lifetime," in the words of Gigi Luk, an associate professor at Harvard's Graduate School of Education. At the same time, one of the hottest trends in public schooling is what's often called dual-language or two-way immersion programs. Traditional programs for English-language learners, or ELLs, focus on assimilating students into English as quickly as possible. Dual-language classrooms, by contrast, provide instruction across subjects to both English natives and English learners, in both English and in a target language. The goal is functional bilingualism and biliteracy for all students by middle school. New York City, North Carolina, Delaware, Utah, Oregon and Washington state are among the places expanding dual-language classrooms. © 2016 npr
By NICHOLAS BAKALAR Stroke rates have been declining in older people over the past 20 years — but have sharply increased in those under 55. Researchers at Rutgers University used data from the New Jersey Department of Health on more than 227,000 hospitalizations for stroke from 1995 through 2014, calculating incidence by age over five-year periods. The findings appeared in the Journal of the American Heart Association. Compared with the 1995-99 period, the rate of stroke in 2010-14 increased by 147 percent in people 35 to 39, by 101 percent in people 40 to 44, by 68 percent in those 45 to 49, and by 23 percent in the 50 to 54 group. Stroke is still far more common in older people. But the rate decreased by 11 percent in those 55 to 59, by 22 percent in the 60 to 64 group, and by 18 percent in people 65 to 69. The reasons are unclear, but the lead author, Joel N. Swerdel, now an epidemiologist with Janssen Pharmaceuticals, said that increasing obesity and diabetes in younger people are probably involved. “For a person 30 to 50, the good news is you ain’t dead yet,” he said. “With behavioral changes, changing diet, increasing exercise, there’s still hope for you. Behavioral change is hard, but this study is an early warning sign.” © 2016 The New York Times Company
Link ID: 22929 - Posted: 11.30.2016
By John Horgan Asked for a comment on the language-acquisition theory of Noam Chomsky (in photo above), psychologist Steven Pinker says: “Chomsky has been a piñata, where anyone who finds some evidence that some aspect of language is learned (and there are plenty), or some grammatical phenomenon varies from language to language, claims to have slain the king. It has not been a scientifically productive debate, unfortunately.” Credit: Ministerio de Cultura de la Nación Argentina Flickr (CC BY-SA 2.0) Noam Chomsky’s political views attract so much attention that it’s easy to forget he’s a scientist, one of the most influential who ever lived. Beginning in the 1950s, Chomsky contended that all humans possess an innate capacity for language, activated in infancy by minimal environmental stimuli. He has elaborated and revised his theory of language acquisition ever since. Chomsky’s ideas have profoundly affected linguistics and mind-science in general. Critics attacked his theories from the get-go and are still attacking, paradoxically demonstrating his enduring dominance. Some attacks are silly. For example, in his new book A Kingdom of Speech Tom Wolfe asserts that both Darwin and “Noam Charisma” were wrong. (See journalist Charles Mann’s evisceration of Wolfe.) © 2016 Scientific American
Link ID: 22927 - Posted: 11.29.2016
By Smitha Mundasad Health reporter About 9,000 stroke patients a year are missing out on a treatment that can prevent disability following a stroke, say UK experts. Clot retrieval can restore blood flow to the brain, preventing some lasting damage, but currently only 600 patients a year get this therapy, they estimate. A national stroke audit reveals part of the problem is a lack of skilled staff to do the procedure. NHS England says stroke patients are receiving high quality care. During a stroke, the blood supplying vital parts of the brain is interrupted. The most common reason is a clot blocking a major blood vessel in the head, although some strokes are caused by a bleed. The longer a part of the brain is starved of blood, the more likely lasting damage - such as paralysis and speech problems - will occur. Expanding mesh While many people with a stroke caused by a clot currently get drugs to help dissolve the blockage, this does not always work completely. Thrombectomy - or clot retrieval - is another method, which aims to remove the clot mechanically. It is a highly skilled operation, and stroke services need to be set up to be able to deliver the treatment. A thin metal wire housing a mesh is inserted into a major artery in the leg and, under X-ray guidance, it is directed to the site of the problem in the brain. The mesh is then expanded, like a miniature fishing net, to trap and remove the clot. 'Once the clot was out, the damage stopped' © 2016 BBC
Link ID: 22923 - Posted: 11.29.2016
Gabrielle Emanuel "It's frustrating that you can't read the simplest word in the world." Thomas Lester grabs a book and opens to a random page. He points to a word: galloping. "Goll—. G—. Gaa—. Gaa—. G—. " He keeps trying. It is as if the rest of the word is in him somewhere, but he can't sound it out. "I don't ... I quit." He tosses the book and it skids along the table. Despite stumbling over the simplest words, Thomas – a 4th grader – is a bright kid. In fact, that's an often-misunderstood part of dyslexia: It's not about lacking comprehension, having a low IQ or being deprived of a good education. It's about having a really hard time reading. Dyslexia is the most common learning disability in the United States. It touches the lives of millions of people, including me and Thomas. Just like Thomas, I spent much of my childhood sitting in a little chair across from a reading tutor. Today, Thomas is working with his tutor in an office building on the northwest side of Washington, D.C. The suite they're in is an oasis of white couches and overstuffed pillows. In the waiting area, a kid is curled up sucking her thumb, and a mom reads a magazine quietly. In the back of the suite — a Lindamood Bell Reading Center — Thomas fidgets with everything in arm's reach. "Alright, I am going to give you some air-writing words," the tutor says to Thomas, speaking rapidly as if daring Thomas to keep pace. She spells the first one out loud: "C-O-R-T." With his index finger, Thomas writes the letters sloppily in the air. Then, his tutor asks a question: What sound do the two middle letters make? "Eer? Aar?" Thomas squints at whatever visual memory he can retain from the letters he's just scribbled in the air. Then, with a burst of enthusiasm, he stumbles on the answer: "Or!" © 2016 npr
Link ID: 22918 - Posted: 11.28.2016
By NICHOLAS BAKALAR Having one or two alcoholic drinks a day is associated with a lower risk of stroke, a review of studies has found. But drinking more than that increases the risk. The analysis, in BMC Medicine, used data from 27 studies. Compared with nondrinkers or occasional drinkers, people who had one or two drinks a day had an 8 percent reduced risk of ischemic stroke. Ischemic strokes, caused by blockage of an artery supplying blood to the brain, account for about 87 percent of all strokes. Heavier drinking, however, increased stroke risk. Having up to four daily drinks led to an 8 percent increased risk of ischemic stroke, and at more than four drinks, the risk increased by 14 percent. Drinking more than four drinks a day also increased the risk of hemorrhagic stroke, the result of a burst or leaking blood vessel in or near the brain, by up to 82 percent. More moderate drinking did not raise hemorrhagic stroke risk. The lead author, Susanna C. Larsson, an associate professor of epidemiology at the Karolinska Institutet in Sweden, warned that alcohol is not health food. “Nondrinkers should not start to drink as a health measure,” she said. “And I wouldn’t recommend that a person who has a drink or two on the weekend increase his consumption.” © 2016 The New York Times Company