Chapter 13. Memory, Learning, and Development

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By Meredith Wadman There have been few happy endings when it comes to spinal muscular atrophy (SMA), the most common genetic cause of death in childhood. The disease inexorably destroys the motor neurons of the spinal cord and brainstem that control movement, including swallowing and breathing. In its most severe form, SMA kills those afflicted at about age 2, most commonly by suffocating them. There are no Food and Drug Administration (FDA)–approved drugs for the disease. That is almost certainly about to change. An innovative drug that helps cells bypass the genetic flaw responsible for SMA may be approved as soon as this month, on the heels of strongly positive results from late-stage clinical trials. On 7 November, a trial of the drug, nusinersen, in wheelchair-bound children aged 2 to 12, was stopped on the grounds that it was unethical to deny the drug to children in the control arm, given the positive results in the treated children. In August, a similar trial in infants was stopped for the same reason, allowing the untreated infants in a control arm to begin receiving the drug. And today, a paper appearing in The Lancet provides compelling biological evidence that nusinersen is having its desired effect in the cells of the brain and spinal cord. “These [infant-onset] SMA kids are going to die. And not only are they now not dying, you are essentially on the path to a true cure of a degenerative [neurological] disease, which is unheard of,” says Jeffrey Rothstein, a neurologist at the Johns Hopkins School of Medicine in Baltimore, Maryland, who was not affiliated with the trials of the drug and is not connected with either of the two companies involved in its development: Ionis of Carlsbad, California, and Biogen of Cambridge, Massachusetts. © 2016 American Association for the Advancement of Science

Keyword: Movement Disorders; Development of the Brain
Link ID: 22967 - Posted: 12.08.2016

Laura Sanders Flickering light kicks off brain waves that clean a protein related to Alzheimer’s disease out of mice’s brains, a new study shows. The results, described online December 7 in Nature, suggest a fundamentally new approach to counteracting Alzheimer’s. Many potential therapies involve drugs that target amyloid-beta, the sticky protein that accumulates in the brains of Alzheimer’s patients. In contrast, the new method used on mice causes certain nerve cells to fire at a specific rhythm, generating brain waves that researchers believe may clear A-beta. “This is a very creative and innovative new approach to targeting brain amyloid load in Alzheimer’s,” says geriatric psychiatrist Paul Rosenberg of Johns Hopkins Medicine. But he cautions that the mouse results are preliminary. Neuroscientist Li-Huei Tsai of MIT and colleagues saw that mice engineered to produce lots of A-beta don’t produce as many gamma waves in the hippocampus, a brain structure important for memory. Using a method called optogenetics, the researchers genetically designed certain nerve cells in the hippocampus to fire off signals in response to light. In this way, the researchers induced gamma waves — rhythmic firings 40 times per second. After just an hour of forced gamma waves, the mice had less A-beta in the hippocampus, the researchers found. Further experiments revealed that gamma waves packed a double whammy — they lowered A-beta by both reducing production and enhancing the brain’s ability to clear it. © Society for Science & the Public 2000 - 2016

Keyword: Alzheimers
Link ID: 22966 - Posted: 12.08.2016

By Helen Briggs BBC News Humans may in part owe their big brains to a DNA "typo" in their genetic code, research suggests. The mutation was also present in our evolutionary "cousins" - the Neanderthals and Denisovans. However, it is not found in humans' closest living relatives, the chimpanzees. As early humans evolved, they developed larger and more complex brains, which can process and store a lot of information. Last year, scientists pinpointed a human gene that they think was behind the expansion of a key brain region known as the neocortex. They believe the gene arose about five or six million years ago, after the human line had split off from chimpanzees. Now, researchers have found a tiny DNA change - a point mutation - that appears to have changed the function of the gene, sparking the process of expansion of the neocortex. It may have paved the way for the brain's expansion by dramatically boosting the number of brain cells found in this region. Dr Wieland Huttner of the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany, led the research. "A point mutation in a human-specific gene gave it a function that allows expansion of the relevant stem cells that make a brain big," he told BBC News. "This one, as it is fixed in the human genome - so all living humans have the gene - apparently gave a tremendous selection advantage, and that's why we believe it spread in the human population." Between two and six million years ago, the ancestors of modern humans began to walk upright and use simple tools.

Keyword: Evolution; Genes & Behavior
Link ID: 22965 - Posted: 12.08.2016

Children don’t usually have the words to communicate even the darkest of thoughts. As a result, some children aged 5 to 11 take their own lives. It’s a rare and often overlooked phenomenon—and one that scientists are only just beginning to understand. A study published today in the journal Pediatrics reveals that attention deficit disorder (A.D.D.), not depression, may be the most common mental health diagnosis among children who die by suicide. By contrast, the researchers found that two-thirds of the 606 early adolescents studied (aged 12 to 14) had suffered from depression. While the finding isn’t necessarily causal, it does suggest that impulsive behavior might contribute to incidences of child suicide. Alternatively, some of these cases could be attributed to early-onset bipolar disorder, misdiagnosed as A.D.D. or A.D.H.D. Here’s Catherine Saint Louis, reporting for The New York Times: Suicide prevention has focused on identifying children struggling with depression; the new study provides an early hint that this strategy may not help the youngest suicide victims. “Maybe in young children, we need to look at behavioral markers,” said Jeffrey Bridge, the paper’s senior author and an epidemiologist at the Research Institute at Nationwide Children’s Hospital in Columbus, Ohio. Jill Harkavy-Friedman, the vice president of research at the American Foundation for Suicide Prevention, agreed. “Not everybody who is at risk for suicide has depression,” even among adults, said Dr. Harkavy-Friedman, who was not involved in the new research. © 1996-2016 WGBH Educational Foundation

Keyword: ADHD; Depression
Link ID: 22964 - Posted: 12.08.2016

By MATT RICHTEL Soaring use of e-cigarettes among young people “is now a major public health concern,” according to a report being published Thursday from the United States Surgeon General. It is the first comprehensive look on the subject from the nation’s highest public-health authority, and it finds that e-cigarettes are now the most commonly used tobacco product among youths, surpassing tobacco cigarettes. E-cigarettes, which turn nicotine into inhalable vapor, can harm developing brains of teenagers who use them, and also can create harmful aerosol for people around the user, the equivalent of secondhand smoke, the report said, citing studies in animals. “Adolescent brains are particularly sensitive to nicotine’s effects,” and can experience “a constellation of nicotine-induced neural and behavioral alterations,” the report said. It urged stronger action to prevent young people from getting access to e-cigarettes. Some researchers have said that e-cigarette use among youth could act as a gateway to traditional smoking, but the report says the relationship is not yet fully established. Cigarette smoking among youth has fallen sharply in recent years but use of nicotine products over all remains essentially flat among young people. With its focus on youth, the report did not address adult use of e-cigarettes, and the most divisive issue of whether the technology is an effective tool to help smokers of traditional cigarettes quit their deadly habit. The report also did not break new scientific ground, but public health advocates said the voice of the surgeon general in the debate marked a milestone. “It’s the most comprehensive and objective answer to the question of whether e-cigarette use is a matter of serious concern that requires government action,” said Matthew Myers, President of the Campaign for Tobacco Free Kids. “The answer, based on the findings, is: yes.” © 2016 The New York Times Company

Keyword: Drug Abuse; Development of the Brain
Link ID: 22963 - Posted: 12.08.2016

By MARC SANTORA At least four babies have been born in New York City with Zika-related brain developmental symptoms since July, the city’s health department said on Wednesday, bringing the total number of such births to five. The numbers were announced in an alert the Department of Health and Mental Hygiene sent to doctors, urging them to remain vigilant and to continue to warn pregnant women and sexually active women of reproductive age not using a reliable form of birth control against traveling to places where the virus is spreading. It was a reminder that while the threat of the virus may have eased in many places around the world, it still poses a danger and its consequences are likely to be felt for some time. Zika is primarily transmitted by mosquitoes but can also be passed on through sex. In most cases, the virus causes only mild illness, but the danger to women pregnant or trying to become pregnant is much greater, because of the impact the disease can have on fetal development. A small percentage of women with the virus have given birth to infants with a abnormally small heads and stunted brain growth — a condition known as microcephaly. As of Friday, about 8,000 New Yorkers have been tested for Zika and 962 have tested positive, including 325 pregnant women, according to the health department. All the cases were associated with travel; six involved sexual transmission by a partner who had been to the areas hit hardest by the Zika epidemic. © 2016 The New York Times Company

Keyword: Development of the Brain
Link ID: 22958 - Posted: 12.07.2016

By Michael Price The titular detective of the BBC television series Sherlock possesses a “mind palace”—a highly organized mental catalog of nearly every memory he’s ever had. We mere mortals can’t match Holmes’s remarkable recollection, but when we store and recall memories, our brain activity probably looks a lot like his, according to a new study. The findings might help us find early warning signs of memory loss in diseases like Alzheimer’s. Previous research has found that when people perceive an event for the first time and when they are asked to remember it later, the same brain regions are activated. But whether different people encode the same memory in the same way has been a topic of debate. So scientists turned to Sherlock Holmes for answers. A group led by Janice Chen, a postdoc in the psychology department at Princeton University, and Yuan Chang Leong, a graduate student studying psychology at Stanford University in Palo Alto, California, strapped 22 study participants into a functional magnetic resonance imaging (fMRI) machine, which traces blood flow in the brain to measure brain activity. The scientists then showed them a 48-minute segment of BBC’s Sherlock. (Roughly the first half of the series’s first episode, “A Study in Pink,” for the curious superfans.) Immediately afterward, Chen asked the volunteers to tell her as much about the episode as they could. © 2016 American Association for the Advancement of Science.

Keyword: Learning & Memory
Link ID: 22956 - Posted: 12.06.2016

By CHRISTOPHER MELE Have you called your daughter by your wife’s name or your son by his brother’s name? Have you misplaced your car keys or forgotten where you parked at the mall? If you worry these might be signs of significant memory loss or the early stages of Alzheimer’s disease, which causes a slow deterioration in memory and reasoning skills, fear not, experts said. By the age of 45, the average person experiences a decline in memory, Dr. Gary W. Small, a professor of psychiatry and biobehavioral sciences at the David Geffen School of Medicine at the University of California, Los Angeles, said in an email. Forgetting facts or events over time, absent-mindedness and incorrectly recalling a detail are among six “normal” memory problems that should not cause concern, according to the Center for Brain-Mind Medicine at Brigham and Women’s Hospital in Boston. When people do experience normal memory decline related to aging, 85 percent of their complaints involve recalling people’s names, Dr. Small said. You can blame multitasking for overloading your mind. Think about the ways we are driven to distraction with smartphones and social media, for instance. “Whenever our brains are taxed by multiple demands, cognitive ‘slips’ or errors are more likely to occur due to a concept called memory ‘interference,’ ” Carrington Wendell, a neuropsychology specialist at the Anne Arundel Medical Group in Annapolis, Md., said in an email. Name mix-ups are also more likely to occur when the two names share the same beginning, middle or ending, such as Bob and Ben or Dave and Jake, and are the same sex and similar age, she added. © 2016 The New York Times Company

Keyword: Learning & Memory; Alzheimers
Link ID: 22955 - Posted: 12.06.2016

By PETER GODFREY-SMITH Around 2008, while snorkeling and scuba diving in my free time, I began watching the unusual group of animals known as cephalopods, the group that includes octopuses, cuttlefish and squid. The first ones I encountered were giant cuttlefish, large animals whose skin changes color so quickly and completely that swimming after them can be like following an aquatic, multi-armed television. Then I began watching octopuses. Despite being mollusks, like clams and oysters, these animals have very large brains and exhibit a curious, enigmatic intelligence. I followed them through the sea, and also began reading about them, and one of the first things I learned came as a shock: They have extremely short lives — just one or two years. I was already puzzled by the evolution of large brains in cephalopods, and this discovery made the questions more acute. What is the point of building a complex brain like that if your life is over in a year or two? Why invest in a process of learning about the world if there is no time to put that information to use? An octopus’s or cuttlefish’s life is rich in experience, but it is incredibly compressed. The particular puzzle of octopus life span opens up a more general one. Why do animals age? And why do they age so differently? A scruffy-looking fish that inhabits the same patch of sea as my cephalopods has relatives who live to 200 years of age. This seems extraordinarily unfair: A dull-looking fish lives for centuries while the cuttlefish, in their chromatic splendor, and the octopuses, in their inquisitive intelligence, are dead before they are 2? There are monkeys the size of a mouse that can live for 15 years, and hummingbirds that can live for over 10. Nautiluses (who are also cephalopods) can live for 20 years. A recent Nature paper reported that despite continuing medical advances, humans appear to have reached a rough plateau at around 115 years, though a few people will edge beyond it. The life spans of animals seem to lack all rhyme or reason. © 2016 The New York Times Company

Keyword: Intelligence; Development of the Brain
Link ID: 22951 - Posted: 12.05.2016

By Jessica Boddy Memory researchers have shone light into a cognitive limbo. A new memory—the name of someone you've just met, for example—is held for seconds in so-called working memory, as your brain's neurons continue to fire. If the person is important to you, the name will over a few days enter your long-term memory, preserved by permanently altered neural connections. But where does it go during the in-between hours, when it has left your standard working memory and is not yet embedded in long-term memory? In Science, a research team shows that memories can be resurrected from this limbo. Their observations point to a new form of working memory, which they dub prioritized long-term memory, that exists without elevated neural activity. Consistent with other recent work, the study suggests that information can somehow be held among the synapses that connect neurons, even after conventional working memory has faded. "This is a really fundamental find—it's like the dark matter of memory," says Geoffrey Woodman, a cognitive neuroscientist at Vanderbilt University in Nashville who was not involved with the work. "It's hard to really see it or measure it in any clear way, but it has to be out there. Otherwise, things would fly apart." Cognitive neuroscientist Nathan Rose and colleagues at the University of Wisconsin (UW) in Madison initially had subjects watch a series of slides showing faces, words, or dots moving in one direction. They tracked the resulting neural activity using functional magnetic resonance imaging (fMRI) and, with the help of a machine learning algorithm, showed they could classify the brain activity associated with each item. Then the subjects viewed the items in combination—a word and face, for example—but were cued to focus on just one item. At first, the brain signatures of both items showed up, as measured in this round with electroencephalography (EEG). But neural activity for the uncued item quickly dropped to baseline, as if it had been forgotten, whereas the EEG signature of the cued item remained, a sign that it was still in working memory. Yet subjects could still quickly recall the uncued item when prompted to remember it a few seconds later. © 2016 American Association for the Advancement of Science.

Keyword: Learning & Memory
Link ID: 22947 - Posted: 12.03.2016

Rosie Mestel The 2016 US election was a powerful reminder that beliefs tend to come in packages: socialized medicine is bad, gun ownership is a fundamental right, and climate change is a myth — or the other way around. Stances that may seem unrelated can cluster because they have become powerful symbols of membership of a group, says Dan Kahan, who teaches law and psychology at Yale Law School in New Haven, Connecticut. And the need to keep believing can further distort people’s perceptions and their evaluation of evidence. Here, Kahan tells Nature about the real-world consequences of group affinity and cognitive bias, and about research that may point to remedies. This interview has been edited for length and clarity. One measure is how individualistic or communitarian people are, and how egalitarian or hierarchical. Hierarchical and individualistic people tend to have confidence in markets and industry: those represent human ingenuity and power. People who are egalitarian and communitarian are suspicious of markets and industry. They see them as responsible for social disparity. It’s natural to see things you consider honourable as good for society, and things that are base, as bad. Such associations will motivate people’s assessment of evidence. Can you give an example? In a study, we showed people data from gun-control experiments and varied the results1. People who were high in numeracy always saw when a study supported their view. If it didn’t support their view, they didn’t notice — or argued their way out of it. © 2016 Macmillan Publishers Limited

Keyword: Attention; Emotions
Link ID: 22946 - Posted: 12.03.2016

Erika Check Hayden Physicians may soon have a lot more help in treating newborns. Neuroscientists and physicians have embarked on what they hope will be a revolution in treatments to prevent brain damage in newborn babies. As many as 800,000 babies die each year when blood and oxygen stop flowing to the brain around the time of birth. And thousands develop brain damage that causes long-lasting mental or physical disabilities, such as cerebral palsy. Physicians have few tools to prevent this, but they are optimistic that clinical trials now under way will change things. The trials were sparked by neuroscientists’ realization in the 1990s that some brain injuries can be repaired. That discovery spurred a flurry of basic research that is just now coming to fruition in the clinic. In January, a US study will start to test whether the hormone erythropoietin, or EPO, can prevent brain damage hours after birth when combined with hypothermia, in which babies are cooled to 33.5 °C. A trial in Australia is already testing this treatment. Physicians in countries including the United States, China and Switzerland are testing EPO in premature babies, as well as other treatments, such as melatonin, xenon, argon, magnesium, allopurinol and cord blood in full-term babies. “The world has really changed for us,” says neurologist Janet Soul at Boston Children’s Hospital in Massachusetts. Therapeutic hypothermia was the first success: clinical trials over the past decade have shown that it decreases the risk of death and of major brain-development disorders by as much as 60%. It is now standard treatment for babies in developed countries whose brains are deprived of blood and oxygen during birth. © 2016 Macmillan Publishers Limited,

Keyword: Development of the Brain
Link ID: 22935 - Posted: 11.30.2016

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

Keyword: Language; Learning & Memory
Link ID: 22934 - Posted: 11.30.2016

By Andy Coghlan Don’t go to bed angry. Now there’s evidence for this proverb: it’s harder to suppress bad memories if you sleep on them. The discovery could reveal new ways to treat people who suffer from conditions like post-traumatic stress disorder, and reinforces an earlier idea that it is possible to suppress bad memories through sleep deprivation. “The results are of major interest for treating the frequent clinical problem of unwanted memories, memories of traumatic events being the most prominent example,” says Christoph Nissen at the University of Freiburg Medical Center in Germany, who was not involved in the work. In the study, 73 male students memorised 26 mugshots, each paired with a disturbing image, such as a mutilated body, corpse or crying child. The next day they were asked to recall the images associated with half the mugshots and actively try to exclude memories of the rest of the associated images. The group were then directed to memorise another 26 pairs of mugshots and nasty images. Half an hour later they again thought about half the associated images and actively suppressed memories of the rest. Finally, they were asked to describe the image associated with each of the 52 mugshots. The idea was to see if trying to suppress a bad memory works better before or after sleep. © Copyright Reed Business Information Ltd.

Keyword: Sleep; Learning & Memory
Link ID: 22933 - Posted: 11.30.2016

By Dwayne Godwin, Jorge Cham © 2016 Scientific American,

Keyword: Development of the Brain; Trophic Factors
Link ID: 22914 - Posted: 11.26.2016

Alison Abbott & Elie Dolgin A drug that was seen as a major test of the leading theory behind Alzheimer’s disease has failed in a large trial of people with mild dementia. Critics of the ‘amyloid hypothesis’, which posits that the disease is triggered by a build-up of amyloid protein in the brain, have seized on the results as evidence of its weakness. But the jury is still out on whether the theory will eventually yield a treatment. Proponents of the theory note that the particular way in which solanezumab, the drug involved in the trial, works could have led to the failure, rather than a flaw in the hypothesis itself. And many trials are ongoing to test whether solanezumab — or others that target amyloid — could work in people at risk of the disease who have not yet shown symptoms, or even in people with Alzheimer’s, despite the latest negative result. “I’m extremely disappointed for patients, but this, for me, doesn’t change the way I think about the amyloid hypothesis,” says Reisa Sperling, a neurologist at the Brigham and Women’s Hospital in Boston, Massachusetts. She is leading one of several ongoing ‘prevention’ trials that is testing solanezumab, and other drugs that aim to reduce the build-up of amyloid ‘plaques’, in people at risk of developing Alzheimer’s. Solanezumab is an antibody that mops up amyloid proteins from the blood and cerebrospinal fluid. The proteins can go on to form plaques in the brain. Eli Lilly, the company that developed solanezumab, announced on 23 November that it would abandon the drug as a treatment for patients with mild dementia. The outcome adds to a long list of promising Alzheimer’s drugs that have flopped in the clinic, many of which, like solanezumab, targeted amyloid. © 2016 Macmillan Publishers Limited

Keyword: Alzheimers
Link ID: 22912 - Posted: 11.25.2016

By Virginia Morell At last, scientists may have an answer to a question every dog owner asks: Does your pet remember the things you do together? For people, at least, the ability to consciously recall personal experiences and events is thought to be linked to self-awareness. It shapes how we think about the past—and how we predict the future. Now, a new study suggests that dogs also have this type of memory, indicating that the talent may be more common in other animals than previously recognized. The study, “is a creative approach to trying to capture what’s on a dog’s mind,” says Alexandra Horowitz, a dog cognition scientist at Barnard College in New York City who was not involved in the research. The idea that nonhuman animals can consciously remember things they’ve done or witnessed in the past, called episodic memory, is controversial—largely because it’s thought that these animals aren’t self-aware. But scientists have shown that species like Western scrub jays, hummingbirds, rats, and the great apes—those that have to recall complex sequences of information in order to survive—have “episodiclike” memory. For instance, the jays remember what food they’ve hidden, where they stashed it, when they did so, and who was watching while they did it. But what about recalling things that aren’t strictly necessary for survival, or someone else’s actions? To find out whether dogs can remember such details, scientists asked 17 owners to teach their pets a trick called “do as I do.” The dogs learned, for instance, that after watching their owner jump in the air, they should do the same when commanded to “do it!” © 2016 American Association for the Advancement of Science.

Keyword: Learning & Memory
Link ID: 22906 - Posted: 11.25.2016

By PAM BELLUCK It is the news that doctors and families in the heart of Zika territory had feared: Some babies not born with the unusually small heads that are the most severe hallmark of brain damage as a result of the virus have developed the condition, called microcephaly, as they have grown older. The findings were reported in a study of 13 babies in Brazil that was published Tuesday in Morbidity and Mortality Weekly Report. At birth, none of the babies had heads small enough to receive a diagnosis of microcephaly, but months later, 11 of them did. For most of those babies, brain scans soon after birth showed significant abnormalities, and researchers found that as the babies aged, their brains did not grow or develop enough for their age and body size. The new study echoes another published this fall, in which three babies were found to have microcephaly later in their first year. As they closed in on their first birthdays, many of the babies also had some of the other developmental and medical problems caused by Zika infection, a range of disabilities now being called congenital Zika syndrome. The impairments resemble characteristics of cerebral palsy and include epileptic seizures, muscle and joint problems and difficulties swallowing food. “There are some areas of great deficiency in the babies,” said Dr. Cynthia Moore, the director of the division of congenital and developmental disorders for the Centers for Disease Control and Prevention and an author of the new study. “They certainly are going to have a lot of impairment.” Dr. Deborah Levine, a professor of radiology at Harvard Medical School who has studied Zika but was not involved in either study, said there would most likely be other waves of children whose brains were affected by the Zika infection, but not severely enough to be noticed in their first year. © 2016 The New York Times Company

Keyword: Development of the Brain
Link ID: 22903 - Posted: 11.23.2016

Laura Sanders Harmful factors circulating in old blood may be partly responsible for the mental decline that can come with age, a small study in mice suggests. Irina Conboy of the University of California, Berkeley and colleagues devised a new way to mingle blood in two mice that didn’t involve stitching their bodies together, as in previous experiments (SN: 5/31/14, p. 8). Instead, researchers used a microfluidic device to shuttle blood, a process that precisely controlled the timing and amount of blood transferred between the mice. The method, reported online November 22 in Nature Communications, allows more precise tests of blood’s influence on aging, the researchers believe. Old mice benefited in some ways from infusions of young blood, experiments with four young-old pairs of mice revealed. With young blood around, old muscles were better able to recover after an injury. And young blood seemed to improve old livers in some tests. But young blood didn’t seem to help one measure of brain health. After transfusions of young blood, old mice still had lower numbers of newborn nerve cells in the hippocampus, a brain structure important for learning and memory. What’s more, old blood reduced the number of newborn nerve cells in young mice. This damage happened quickly, after just one blood exchange, the researchers found. The results suggest that old blood contains components that harm brain cells, an insight that makes scientists eager to identify those factors. |© Society for Science & the Public 2000 - 2016

Keyword: Development of the Brain
Link ID: 22898 - Posted: 11.23.2016

By GINA KOLATA Despite fears that dementia rates were going to explode as the population grows older and fatter, and has more diabetes and high blood pressure, a large nationally representative survey has found the reverse. Dementia is actually on the wane. And when people do get dementia, they get it at older and older ages. Previous studies found the same trend but involved much smaller and less diverse populations like the mostly white population of Framingham, Mass., and residents of a few areas in England and Wales. The new study found that the dementia rate in Americans 65 and older fell by 24 percent over 12 years, to 8.8 percent in 2012 from 11.6 percent in 2000. That trend is “statistically significant and impressive,” said Samuel Preston, a demographer at the University of Pennsylvania who was not associated with the study. In 2000, people received a diagnosis of dementia at an average age of 80.7; in 2012, the average age was 82.4. “The dementia rate is not immutable,” said Dr. Richard Hodes, director of the National Institute on Aging. “It can change.” And that “is very good news,” said John Haaga, director of the institute’s division of behavioral and social research. It means, he said, that “roughly a million and a half people aged 65 and older who do not have dementia now would have had it if the rate in 2000 had been in place.” Keith Fargo, director of scientific programs and outreach at the Alzheimer’s Association, said the group had been encouraged by some of the previous research showing a decline but had also been “a little bit nervous” about drawing conclusions because the populations in the earlier studies were so homogeneous. Now, he said of the new data, “here is a nationally representative study. It’s wonderful news.” © 2016 The New York Times Company

Keyword: Alzheimers
Link ID: 22896 - Posted: 11.22.2016