Chapter 13. Memory, Learning, and Development
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By Elizabeth Pennisi In the animal kingdom, humans are known for our big brains. But not all brains are created equal, and now we have new clues as to why that is. Researchers have uncovered eight genetic variations that help determine the size of key brain regions. These variants may represent “the genetic essence of humanity,” says Stephan Sanders, a geneticist and pediatrician at the University of California, San Francisco, who was not involved in the study. These results are among the first to come out of the ENIGMA (Enhancing Neuro Imaging Genetics through Meta-Analysis) collaboration, involving some 300 scientists from 33 countries. They contributed MRI scans of more than 30,000 people, along with genetic and other information, most of which had been collected for other reasons. “This paper represents a herculean effort,” Sanders says. Only by pooling their efforts could the researchers track down subtle genetic influences on brain size that would have eluded discovery in smaller studies. “We were surprised we found anything at all,” says Paul Thompson, a neuroscientist at the University of Southern California in Los Angeles. But in the end, “we were able to identify hot points in the genome that help build the brain.” For the analyses, Thompson and his colleagues looked for single-letter (nucleotide base) changes in DNA that correspond to the sizes of key brain regions. One region, the hippocampus, stores memories and helps one learn. Another, called the caudate nucleus, makes it possible to ride a bike, play an instrument, or drive a car without really thinking about it. A third is the putamen, which is involved in running, walking, and moving the body as well as in motivation. The researchers did not try to examine the neocortex, the part of the brain that helps us think and is proportionally much bigger in humans than in other animals. The neocortex has crevices on its surface that look so different from one individual to the next that it’s really hard to measure consistently across labs. © 2015 American Association for the Advancement of Science
By BENEDICT CAREY The surge of emotion that makes memories of embarrassment, triumph and disappointment so vivid can also reach back in time, strengthening recall of seemingly mundane things that happened just beforehand and that, in retrospect, are relevant, a new study has found. The report, published Wednesday in the journal Nature, suggests that the television detective’s standard query — “Do you remember any unusual behavior in the days before the murder?” — is based on solid brain science, at least in some circumstances. The findings fit into the predominant theory of memory: that it is an adaptive process, continually updating itself according to what knowledge may be important in the future. The new study suggests that human memory has, in effect, a just-in-case file, keeping seemingly trivial sights, sounds and observations in cold storage for a time in case they become useful later on. But the experiment said nothing about the effect of trauma, which shapes memory in unpredictable ways. Rather, it aimed to mimic the arousals of daily life: The study used mild electric shocks to create apprehension and measured how the emotion affected memory of previously seen photographs. In earlier work, researchers had found plenty of evidence in animals and humans of this memory effect, called retroactive consolidation. The new study shows that the effect applies selectively to related, relevant information. “The study provides strong evidence for a specific kind of retroactive enhancement,” said Daniel L. Schacter, a professor of psychology at Harvard who was not involved in the research. “The findings go beyond what we’ve found previously in humans.” © 2015 The New York Times Company
Research suggests that only 20–30% of drug users actually descend into addiction — defined as the persistent seeking and taking of drugs even in the face of dire personal consequences. Why are some people who use drugs able to do so without turning into addicts, while others continue to abuse, even when the repercussions range from jail time to serious health problems? In a comprehensive review in the European Journal of Neuroscience, Barry Everitt outlines the neural correlates and learning-based processes associated with the transition from drug use, to abuse, to addiction. Drug seeking begins as a goal-directed behavior, with an action (finding and taking drugs) leading to a particular outcome (the drug high). This type of associative learning is mediated by the dorsomedial region of the striatum, the area of the brain that is associated with reward processing, which functions primarily through the neurotransmitter dopamine. In this kind of learning, devaluing the outcome (by decreasing the potency of the drug, for example) tends to decrease the pursuit of the action. When the high is not what it used to be, the motivation to continue seeking it out decreases. However, in long-term abusers, this devalued outcome does not reduce the action — indeed, researchers have found that in cases of chronic drug use, a parallel associative learning process eventually comes to the fore. This process is one of stimulus–response; the conditioned stimuli in this case are the various environmental cues — the sight of the powdery white stuff, the smell of burning aluminum foil — that users associate with getting high and that compel them to seek out drugs. © Association for Psychological Science
It is now one hundred years since drugs were first banned - and all through this long century of waging war on drugs, we have been told a story about addiction, by our teachers, and by our governments. This story is so deeply ingrained in our minds that we take it for granted. It seems obvious. It seems manifestly true. Until I set off three and a half years ago on a 30,000-mile journey for my book 'Chasing The Scream - The First And Last Days of the War on Drugs' to figure out what is really driving the drug war, I believed it too. But what I learned on the road is that almost everything we have been told about addiction is wrong - and there is a very different story waiting for us, if only we are ready to hear it. If we truly absorb this new story, we will have to change a lot more than the drug war. We will have to change ourselves. I learned it from an extraordinary mixture of people I met on my travels. From the surviving friends of Billie Holiday, who helped me to learn how the founder of the war on drugs stalked and helped to kill her. From a Jewish doctor who was smuggled out of the Budapest ghetto as a baby, only to unlock the secrets of addiction as a grown man. From a transsexual crack dealer in Brooklyn who was conceived when his mother, a crack-addict, was raped by his father, an NYPD officer. From a man who was kept at the bottom of a well for two years by a torturing dictatorship, only to emerge to be elected President of Uruguay and to begin the last days of the war on drugs. ©2015 TheHuffingtonPost.com, Inc.
By PAULA SPAN DEDHAM, Mass. — Jerome Medalie keeps his advance directive hanging in a plastic sleeve in his front hall closet, as his retirement community recommends. That’s where the paramedics will look if someone calls 911. Like many such documents, it declares that if he is terminally ill, he declines cardiopulmonary resuscitation, a ventilator and a feeding tube. But Mr. Medalie’s directive also specifies something more unusual: If he develops Alzheimer’s disease or another form of dementia, he refuses “ordinary means of nutrition and hydration.” A retired lawyer with a proclivity for precision, he has listed 10 triggering conditions, including “I cannot recognize my loved ones” and “I cannot articulate coherent thoughts and sentences.” If any three such disabilities persist for several weeks, he wants his health care proxy — his wife, Beth Lowd — to ensure that nobody tries to keep him alive by spoon-feeding or offering him liquids. VSED, short for “voluntarily stopping eating and drinking,” is not unheard-of as an end-of-life strategy, typically used by older adults who hope to hasten their decline from terminal conditions. But now ethicists, lawyers and older adults themselves have begun a quiet debate about whether people who develop dementia can use VSED to end their lives by including such instructions in an advance directive. Experts know of just a handful of people with directives like Mr. Medalie’s. But dementia rates and numbers have begun a steep ascent, already afflicting an estimated 30 percent of those older than 85. Baby boomers are receiving a firsthand view of the disease’s devastation and burdens as they care for aging parents. They may well prove receptive to the idea that they shouldn’t be kept alive if they develop dementia themselves, predicted Alan Meisel, the director of the University of Pittsburgh’s Center for Bioethics and Health Law. © 2015 The New York Times Company
Link ID: 20495 - Posted: 01.20.2015
Closing your eyes when trying to recall events increases the chances of accuracy, researchers at the University of Surrey suggest. Scientists tested people's ability to remember details of films showing fake crime scenes. They hope the studies will help witnesses recall details more accurately when questioned by police. They say establishing a rapport with the person asking the questions can also help boost memory. Writing in the journal Legal and Criminological Psychology, scientists tested 178 participants in two separate experiments. In the first, they asked volunteers to watch a film showing an electrician entering a property, carrying out work and then stealing a number of items. Volunteers were then questioned in one of four groups. People were either asked questions with their eyes open or closed, and after a sense of rapport had been built with the interviewer or no attempt had been made to create a friendly introduction. People who had some rapport with their interviewer and had their eyes shut throughout questioning answered three-quarters of the 17 questions correctly. But those who did not have a friendly introduction with the interviewer and had their eyes open answered 41% correctly. The analysis showed that eye closing had the strongest impact on remembering details correctly ,but that feeling comfortable during the interview also helped. In the second experiment, people were asked to remember details of what they had heard during a mock crime scene. © 2015 BBC
|By Gareth Cook What is flavor? Beginning with this simple question, the Pulitzer prize-winning journalist John McQuaid weaves a fascinating story with a beginning some half a billion years ago. In his new book, Tasty, McQuaid argues that the sense of taste has played a central role in the evolution of humans. McQuaid’s tale is about science, but also about culture, history and, one senses, our future. What made you decide to write a book about taste? I have two kids, a boy and a girl born two years apart – now teens – and a few years ago, I became fascinated with how their tastes and preferences in food differed. My son liked extremes, especially super-hot chili peppers and whole lemons and limes. My daughter hated that stuff. She preferred bland comfort foods such as mashed potatoes, pasta, cheese and rice. White foods. Both kids were also picky eaters. They liked what they liked, and it didn’t overlap (except for pizza). Speaking as a parent, this was maddening. So I wondered where these differences came from. Were they genetic? The kids had mostly the same genes. Environment? They lived in the same place. And yet clearly both genes and environment were in play somehow. So I began to look into the question, and a whole world opened up. And the basic answer to my original question is: kids are, biologically speaking, weird creatures. Pickiness seems to be programmed by evolution: it would have protected small children from eating strange, possibly poisonous items. Certain preferences, meanwhile, can develop arbitrarily and become very strong, then suddenly fade – every kid goes through phases as the brain matures and the neural networks that shape perception and behavior grow. Each person’s sense of flavor is like a snowflake or a fingerprint, in this way, shaped by partly by genes, but largely by experience. And always changing as more meals are eaten. © 2015 Scientific American
By James Gallagher Health editor, BBC News website The key to learning and memory in early life is a lengthy nap, say scientists. Trials with 216 babies up to 12 months old indicated they were unable to remember new tasks if they did not have a lengthy sleep soon afterwards. The University of Sheffield team suggested the best time to learn may be just before sleep and emphasised the importance of reading at bedtime. Experts said sleep may be much more important in early years than at other ages. People spend more of their time asleep as babies than at any other point in their lives. Yet the researchers, in Sheffield and Ruhr University Bochum, in Germany, say "strikingly little is known" about the role of sleep in the first year of life. Learn, sleep, repeat They taught six- to 12-month-olds three new tasks involving playing with hand puppets. Half the babies slept within four hours of learning, while the rest either had no sleep or napped for fewer than 30 minutes. The next day, the babies were encouraged to repeat what they had been taught. The results, published in Proceedings of the National Academy of Sciences, showed "sleeping like a baby" was vital for learning. On average one-and-a-half tasks could be repeated after having a substantial nap. Yet zero tasks could be repeated if there was little sleep time. Dr Jane Herbert, from the department of psychology at the University of Sheffield, told the BBC News website: "Those who sleep after learning learn well, those not sleeping don't learn at all." © 2015 BBC
by Michael Hotchkiss Forget about it. Your brain is a memory powerhouse, constantly recording experiences in long-term memory. Those memories help you find your way through the world: Who works the counter each morning at your favorite coffee shop? How do you turn on the headlights of your car? What color is your best friend's house? But then your barista leaves for law school, you finally buy a new car and your buddy spends the summer with a paint brush in hand. Suddenly, your memories are out of date. What happens next? An experiment conducted by researchers from Princeton University and the University of Texas-Austin shows that the human brain uses memories to make predictions about what it expects to find in familiar contexts. When those subconscious predictions are shown to be wrong, the related memories are weakened and are more likely to be forgotten. And the greater the error, the more likely you are to forget the memory. "This has the benefit ultimately of reducing or eliminating noisy or inaccurate memories and prioritizing those things that are more reliable and that are more accurate in terms of the current state of the world," said Nicholas Turk-Browne, an associate professor of psychology at Princeton and one of the researchers. The research was featured in an article, "Pruning of memories by context-based prediction error," that appeared in 2014 in the Proceedings of the National Academy of Sciences. The other co-authors are Ghootae Kim, a Princeton graduate student; Jarrod Lewis-Peacock, an assistant professor of psychology at the University of Texas-Austin; and Kenneth Norman, a Princeton professor of psychology and the Princeton Neuroscience Institute. © Medical Xpress 2011-2014,
Keyword: Learning & Memory
Link ID: 20469 - Posted: 01.10.2015
Rose Eveleth Ranking pain isn’t a simple thing. The standard scale that goes from one to 10, often accompanied by smiley faces that become increasingly distressed, has been lampooned by many as being difficult to use. What does it mean to be a five? Or a three? What is that mildly sad frowny face saying? Do you have to be crying for it to really be a 10? And for some people, it’s even harder to put a number to a subjective experience. Patients with autism, for example, often struggle to express the pain they’re feeling. “We do see many members of our community who either experience altered pain perception, or who have difficulties communicating about and reporting pain,” Julia Bascom, the director of programs at the Autistic Self Advocacy Network, told me in an email. “So someone might experience acid reflux not as burning pain, but as pressure in their throat, and then struggle to interpret a numerical pain scale, or not realize they should bring the issue to the attention of those around them—or what words to use to be taken seriously.” Autism can also mean a difficulty interpreting facial expressions, so the happy and sad faces wouldn't be the most helpful visual cues. And some autistic patients aren’t verbal at all. In fact, for a long time, people thought that kids with autism didn’t feel pain at all, because they often didn’t show reactions to it the same way other people do. “They might not understand the words other people use to describe pain, even if they are feeling the exact same sensation, and their outward reactions might seem to indicate much more pain than they are actually feeling,” Bascom said. © 2015 by The Atlantic Monthly Group.
|By Tori Rodriguez Coffee and tea may do more than just jolt you awake—they could also help keep your brain healthy, according to a slew of recent studies. Researchers have linked these beverages with protection from depression, Alzheimer's disease and Parkinson's disease. One large study investigated the link between depression and the intake of coffee, tea and sweet drinks [see box below]by following more than a quarter of a million older adults for 10 years. Researchers at the National Institutes of Health recorded consumption of each type of beverage in 1995 and 1996 and then compared those figures with participants' self-reported diagnoses of depression after 2000. Results showed that coffee intake was associated with a slightly lower risk for depression, according to a paper published last April in PLOS ONE. The paper found little effect from tea, but other work has shown tea to be protective. A study reported in November 2013 found older Chinese adults who regularly drank any kind of tea had a significantly smaller risk for depression: 21 percent for those who drank tea between one and five days a week and 41 percent for daily drinkers. The researchers also asked about the participants' leisure activities to ensure that the tea, and not teatime socializing, provided the protective effect. Some studies suggest that coffee and tea drinkers have lower rates of cognitive decline, too, but the evidence is mixed. Research in rodents that has focused on specific compounds in coffee and tea supports the idea that some of these chemicals reduce the risk for Alzheimer's and Parkinson's. In one such study, published online last June in Neurobiology of Aging, supplementing rats' diets with a component of coffee called eicosanoyl-5-hydroxytryptamide shielded the animals' brains against the pathological changes typical of Alzheimer's. © 2015 Scientific American,
by Lisa Seachrist Chiu Just before winter break, my fifth grader came home from school, opened her mouth and produced what sounded to me like a stuttering mess of gibberish. After complaining that when she spends the entire day immersed in Chinese, she sometimes can’t figure out what language to use, she carried on speaking flawless English to me and Chinese to a friend while they did their homework. Quite honestly, I had been eagerly anticipating this very day for a long time. Having worked several years to establish the Chinese language immersion elementary school my daughter attends, I could barely contain my excitement at this demonstration that she truly grasps a second language. Early language programs are hot, in no small part because, when it comes to language, kids under the age of 7 are geniuses. Like many parents, I wanted my child to be fluent in as many languages as possible so she can communicate with more people and because it gives her a prime tool to explore different cultures. Turns out, it may also benefit her brain. With the help of advanced imaging tools that reveal neural processes in specific brain structures, researchers are coalescing around the idea that fluency in more than one language heightens executive function — the ability to regulate and control cognitive processes. It’s a radical shift from just a few decades ago when psychologists routinely warned against raising children who speak two languages, lest they become confused and suffer delays in learning. © Society for Science & the Public 2000 - 2014
Link ID: 20448 - Posted: 01.01.2015
Three-year outcomes from an ongoing clinical trial suggest that high-dose immunosuppressive therapy followed by transplantation of a person's own blood-forming stem cells may induce sustained remission in some people with relapsing-remitting multiple sclerosis (RRMS). RRMS is the most common form of MS, a progressive autoimmune disease in which the immune system attacks the brain and spinal cord. The trial is funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and conducted by the NIAID-funded Immune Tolerance Network (ITN) External Web Site Policy. Three years after the treatment, called high-dose immunosuppressive therapy and autologous hematopoietic cell transplant or HDIT/HCT, nearly 80 percent of trial participants had survived without experiencing an increase in disability, a relapse of MS symptoms or new brain lesions. Investigators observed few serious early complications or unexpected side effects, although many participants experienced expected side effects of high-dose immunosuppression, including infections and gastrointestinal problems. The three-year findings are published in the Dec. 29, 2014, online issue of JAMA Neurology. “These promising results support the need for future studies to further evaluate the benefits and risks of HDIT/HCT and directly compare this treatment strategy to current MS therapies,” said NIAID Director Anthony S. Fauci, M.D. “If the findings from this study are confirmed, HDIT/HCT may become a potential therapeutic option for people with this often-debilitating disease, particularly those who have not been helped by standard treatments.”
George Johnson Training a dog to salivate at the sound of a bell would have seemed pretty stupid to Ivan Pavlov. He was after much bigger things. Using instruments like metronomes and harmoniums, he demonstrated that a dog could make astonishingly fine discriminations — distinguishing between a rhythm of 96 and 104 beats a minute or an ascending and a descending musical scale. But what he really wanted to know was what his animals were thinking. His dream was a grand theory of the mind. He couldn’t put his subjects on a couch like his colleague Freud and ask them to free-associate, so he gauged their reactions to a variety of stimuli, meticulously counting their “psychic secretions,” those droplets of drool. He knew he was pricking at the skin of something deeper. “It would be stupid,” he said, “to reject the subjective world.” This is not the Pavlov most people think they know. In an excellent new biography, “Ivan Pavlov: A Russian Life in Science,” Daniel P. Todes, a medical historian, describes a man whose laboratory in pre-Soviet Russia was like an early-20th-century version of the White House Brain Initiative, with its aim “to revolutionize our understanding of the human mind.” That was also Pavlov’s goal: to build a science that would “brightly illuminate our mysterious nature” and “our consciousness and its torments.” He spoke those words 111 years ago and spent his life pursuing his goal. Yet when we hear his name, we reflexively think of a drooling dog and a clanging bell. Our brains have been conditioned with the myth. © 2014 The New York Times Company
Keyword: Learning & Memory
Link ID: 20439 - Posted: 12.23.2014
By James Gallagher Health editor, BBC News website A link between autism and air pollution exposure during pregnancy has been suggested by scientists. The Harvard School of Public Health team said high levels of pollution had been linked to a doubling of autism in their study of 1,767 children. They said tiny particulate matter, which can pass from the lungs to the bloodstream, may be to blame. Experts said pregnant women should minimise their exposure, although the link had still to be proven. Air pollution is definitely damaging. The World Health Organization estimates it causes 3.7 million deaths each year. The study, published in Environmental Health Perspectives, investigated any possible link with autism. It analysed 245 children with autism and 1,522 without. By looking at estimated pollution exposure during pregnancy, based on the mother's home address, the scientists concluded high levels of pollution were more common in children with autism. The strongest link was with fine particulate matter - invisible specks of mineral dust, carbon and other chemicals - that enter the bloodstream and cause damage throughout the body. Yet, the research is unable to conclusively say that pollution causes autism as there could be other factors that were not accounted for in the study. Consistent pattern There is a large inherited component to autism, but lead researcher Dr Marc Weisskopf said there was mounting evidence that air pollution may play a role too. BBC © 2014
by Helen Thomson HAVE you read this before? A 23-year-old man from the UK almost certainly feels like he has – he's the first person to report persistent déjà vu stemming from anxiety rather than any obvious neurological disorder. Nobody knows exactly how or why déjà vu happens, but for most of us it is rare. Some people experience it more often, as a side effect associated with epileptic seizures or dementia. Now, researchers have discovered the first person with what they call "psychogenic déjà vu" – where the cause appears to be psychological. The man's episodes began just after he started university, a period when he felt anxious and was also experiencing obsessive compulsions. As time went on, his déjà vu became more and more prolonged, and then fairly continuous after he tried LSD. Now, he avoids television and radio, and finds newspapers distressing as the content feels familiar. There are different theories as to what is going on, says Christine Wells at Sheffield Hallam University in the UK, who has written a paper on the man's experiences. "The general theory is that there's a misfiring of neurons in the temporal lobes – which deal with recollection and familiarity. That misfiring during the process of recollection means we interpret a moment in time as something that has already been experienced," she says. Surprisingly, when Wells gave the man a standard recall test, he scored more similarly to people of his own age without the condition than those with epilepsy-related déjà vu. An MRI and an EEG scan of his brain activity also showed no abnormalities. © Copyright Reed Business Information Ltd.
|By Marissa Fessenden Songbirds stutter, babble when young, become mute if parts of their brains are damaged, learn how to sing from their elders and can even be "bilingual"—in other words, songbirds' vocalizations share a lot of traits with human speech. However, that similarity goes beyond behavior, researchers have found. Even though humans and birds are separated by millions of years of evolution, the genes that give us our ability to learn speech have much in common with those that lend birds their warble. A four-year long effort involving more than 100 researchers around the world put the power of nine supercomputers into analyzing the genomes of 48 species of birds. The results, published this week in a package of eight articles in Science and 20 papers in other journals, provides the most complete picture of the bird family tree thus far. The project has also uncovered genetic signatures in song-learning bird brains that have surprising similarities to the genetics of speech in humans, a finding that could help scientists study human speech. The analysis suggests that most modern birds arose in an impressive speciation event, a "big bang" of avian diversification, in the 10 million years immediately following the extinction of dinosaurs. This period is more recent than posited in previous genetic analyses, but it lines up with the fossil record. By delving deeper into the rich data set, research groups identified when birds lost their teeth, investigated the relatively slow evolution of crocodiles and outlined the similarities between birds' and humans' vocal learning ability, among other findings. © 2014 Scientific American,
By Candy Schulman My mother’s greatest fear was Alzheimer’s. She got Lewy body dementia, or LBD, instead. This little known, oddly named, debilitating illness afflicts an estimated 1.3 million Americans, the actor and comedian Robin Williams possibly among them. It is often misdiagnosed because its signs, such as hallucinations and body rigidity, do not seem like those of dementia, but in the end it robs people of themselves even more painfully. I first noticed my mother’s cognitive difficulties when she was 88. Until then, she’d led an extraordinarily active life: She was a competitive golfer with a bureau full of trophies, a painter and a sculptor. Every Hanukkah she hosted a lively feast for her eight grandchildren and nine great-grandchildren. This time, though, she needed my help planning, shopping and cooking. She was having difficulty with the guest list, trying to write every family member’s name on a piece of paper, adding up the numbers to see how many potatoes to buy for latkes. Her concentration became frayed and she kept ripping it up and starting again, close to tears. Several months before that, she had sent me a Mother’s Day card that was illustrated with childlike prose, colorful illustrations and glitter hearts. The poem on the cover was printed in a playful purple font: “For you, Mom. For kissing my boo-boos, for wiping my face. . . . For calming my fears with your loving embrace.” On Mother’s Day and the rest of the year, Mom added in a shaky script, “thanks.”
Link ID: 20422 - Posted: 12.16.2014
|By Emilie Reas If you carried a gene that doubled your likelihood of getting Alzheimer's disease, would you want to know? What if there was a simple lifestyle change that virtually abolished that elevated risk? People with a gene known as APOE e4 have a higher risk of cognitive impairment and dementia in old age. Even before behavioral symptoms appear, their brains show reduced metabolism, altered activity and more deterioration than those without the high-risk gene. Yet accumulating research is showing that carrying this gene is not necessarily a sentence for memory loss and confusion—if you know how to work it to your advantage with exercise. Scientists have long known that exercise can help stave off cognitive decline. Over the past decade evidence has mounted suggesting that this benefit is even greater for those at higher genetic risk for Alzheimer's. For example, two studies by a team in Finland and Sweden found that exercising at least twice a week in midlife lowers one's chance of getting dementia more than 20 years later, and this protective effect is stronger in people with the APOE e4 gene. Several others reported that frequent exercise—at least three times a week in some studies; up to more than an hour a day in others—can slow cognitive decline only in those carrying the high-risk gene. Furthermore, for those who carry the gene, being sedentary is associated with increased brain accumulation of the toxic protein beta-amyloid, a hallmark of Alzheimer's. More recent studies, including a 2012 paper published in Alzheimer's & Dementia and a 2011 paper in NeuroImage, found that high-risk individuals who exercise have greater brain activity and glucose uptake during a memory task compared with their less active counterparts or with those at low genetic risk. © 2014 Scientific American
By Nicholas Bakalar Poor sleep in older adults may be linked to brain changes associated with dementia, a new study has found. Researchers studied 167 men who underwent sleep tests in 1999 and died by 2010. The study, in Neurology, recorded sleep duration, periods of waking up and episodes of apnea, and used pulse oximetry to measure oxygen saturation of their blood. On autopsy, they found that those in the highest one-quarter for duration of sleep at oxygen saturation of less than 95 percent were almost four times as likely to have higher levels microinfarcts, small areas of dead tissue caused by deprivation of blood supply, as those in the lowest one-quarter. Compared with those in the lowest 25 percent for duration of slow-wave (deep) sleep, those in the highest one-quarter were about a third as likely to have moderate or high levels of generalized brain atrophy. “Prior studies have shown an association between certain types of sleep disturbance and dementia,” said the lead author, Dr. Rebecca P. Gelber, an epidemiologist with the Veterans Administration in Hawaii. “These lesions may help explain the association.” © 2014 The New York Times Company