Chapter 7. Life-Span Development of the Brain and Behavior

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A new study in Neuron offers clues to why autism spectrum disorder (ASD) is more common in boys than in girls. National Institutes of Health scientists found that a single amino acid change in the NLGN4 gene, which has been linked to autism symptoms, may drive this difference in some cases. The study was conducted at NIH’s National Institute of Neurological Disorders and Stroke (NINDS). Researchers led by Katherine Roche, Ph.D., a neuroscientist at NINDS, compared two NLGN4 genes, (one on the X chromosome and one on the Y chromosome), which are important for establishing and maintaining synapses, the communication points between neurons. Every cell in our body contains two sex chromosomes. Females have two X chromosomes; males have one X and one Y chromosome. Until now, it was assumed that the NLGN4X and NLGN4Y genes, which encode proteins that are 97% identical, functioned equally well in neurons. But using a variety of advanced technology including biochemistry, molecular biology, and imaging tools, Dr. Roche and her colleagues discovered that the proteins encoded by these genes display different functions. The NLGN4Y protein is less able to move to the cell surface in brain cells and is therefore unable to assemble and maintain synapses, making it difficult for neurons to send signals to one another. When the researchers fixed the error in cells in a dish, they restored much of its correct function. “We really need to look at NLGN4X and NLGN4Y more carefully,” said Thien A. Nguyen, Ph.D., first author of the study and former graduate student in Dr. Roche’s lab.

Keyword: Autism; Genes & Behavior
Link ID: 27165 - Posted: 04.03.2020

By Bruce Bower Lucy’s kind had small, chimplike brains that, nevertheless, grew at a slow, humanlike pace. This discovery, reported April 1 in Science Advances, shows for the first time that prolonged brain growth in hominid youngsters wasn’t a by-product of having unusually large brains. An influential idea over the last 20 years has held that extended brain development after birth originated in the Homo genus around 2.5 million years ago, so that mothers — whose pelvic bones and birth canal had narrowed to enable efficient upright walking — could safely deliver babies. But Australopithecus afarensis, an East African hominid species best known for Lucy’s partial skeleton, also had slow-developing brains that reached only about one-third the volume of present-day human brains, say paleoanthropologist Philipp Gunz of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and his colleagues. And A. afarensis is roughly 3 million to 4 million years old, meaning slow brain growth after birth developed before members of the Homo genus appeared, perhaps as early as 2.8 million years ago (SN: 3/4/15). Too few A. afarensis infants have been studied to calculate the age at which this species attained adult-sized brains, Gunz cautions. The brains of human infants today reach adult sizes by close to age 5, versus an age of around 2 or 3 for both chimps and gorillas. In the new study, Gunz and colleagues estimated brain volumes for six A. afarensis adults and two children, estimated to have been about 2 years and 5 months old. The kids had brains that were smaller than adult A. afarensis brain sizes in a proportion similar to human children’s brains at the same age relative to adult humans. © Society for Science & the Public 2000–2020.

Keyword: Evolution; Development of the Brain
Link ID: 27163 - Posted: 04.02.2020

by Laura Dattaro / Mice missing an autism gene called SHANK3 respond to much lighter touches than typical mice do, according to a new study1. And this hypersensitivity seems to result from the underactivity of neurons that normally dampen sensory responses. The study is the first to examine sensory sensitivity in mice missing SHANK3. Mice with mutations in other genes tied to autism, including MECP2 and GABRB3, have also been shown to be hypersensitive to puffs of air blown onto their backs. Up to 90 percent of autistic people have sensory problems, including hypersensitivity to sensations such as sound or touch. These disruptions may underlie many of the difficulties autistic people face in navigating the world, says lead investigator Guoping Feng, professor of neuroscience at the Massachusetts Institute of Technology. “Sensory overload is one of the reasons that autistic people cover their ears, [hide] in corners, want to be quiet,” Feng says. “It’s important to understand mechanisms.” Up to 2 percent of people with autism have a mutation in SHANK3, which encodes a protein needed for neurons to communicate with one another2. Autism is also common in people with Phelan-McDermid syndrome, a condition caused by deletions of the chromosomal region in which SHANK3 is located. Other experts also say the study underscores the importance of studying sensory problems in autistic people. “Hyperreactivity to sensory input might be connected with autism in a really deep way,” says Sam Wang, professor of neuroscience at Princeton University, who was not involved in the work. “If sensory experience in the first few years of life is necessary for setting up a model of the world, an understanding of the world, then sensory processing would be a gateway to all kinds of other difficulties.” © 2020 Simons Foundation

Keyword: Autism; Attention
Link ID: 27151 - Posted: 03.30.2020

By Erika Mailman In summer 2014, when he was 54, Sacramento artist David Wetzl was exhibiting the behaviors of an elderly man with Alzheimer’s. “I have a bad brain,” he told everyone repeatedly, using a simple phrase to explain his diagnosis to the world. Two years before that, his wife, Diana Daniels, had asked for an MRI because she was suspicious that things weren’t right and fearful when he couldn’t remember the word “shoelaces.” The scan showed with horrific clarity how sections of his brain had shriveled. “The devastation began on his left temporal lobe, working its greatest damage,” says Diana. “By the time of diagnosis, his right temporal lobe also had significant atrophy.” David was diagnosed with frontotemporal dementia, or FTD, part of a group of disorders caused by nerve cell damage to the brain. The disease comes with a dispiriting prognosis. There is no cure (although symptoms can be treated), and patients usually die within seven to 13 years from the onset of symptoms. As FTD progresses, behavior can become strange and antisocial, says Matt Ozga, communications manager at the Association for Frontotemporal Degeneration in King of Prussia, Pa. Patients lose their filter and can make embarrassing remarks. For the spouses who are caught off guard, thinking their mate’s worst setback for the next few decades will be graying hair and a paunch, it’s a shock. The couple may find themselves confronted  by different challenges than those who encounter dementia later in life.

Keyword: Alzheimers
Link ID: 27150 - Posted: 03.30.2020

By Nicholas Bakalar There is good evidence that a daily baby aspirin reduces the risk for heart disease and stroke, and some have thought its inflammation-lowering effect might also help in delaying cognitive decline. But taking a daily low-dose aspirin did not appear to be effective in lowering the risk of Alzheimer’s disease or other forms of dementia, a new study reports. For the study, in Neurology, researchers set up a controlled trial with 19,114 men and women older than 70 who were free of cardiovascular disease and dementia at the start. Half were randomly assigned to take a daily 100-milligram aspirin, while the other half took a placebo. After an average follow-up of almost five years with annual examinations, the researchers found no difference between the groups in diagnoses of Alzheimer’s disease or mild cognitive impairment. They did find declining cognitive function over time, but the speed and degree of that decline was the same in both groups. The researchers found no effect in various subgroups either — people with hypertension or diabetes, smokers or people with high cholesterol, or those who were overweight or obese. A limitation of the study was that patients were followed for less than five years. “If you’re 70 or older and healthy, without evidence of cardiovascular disease, it’s very difficult to improve on your success. The relatively low risk of dementia in this study was not further lowered with aspirin,” said a co-author, Dr. Anne B. Newman, a professor of epidemiology at the University of Pittsburgh. © 2020 The New York Times Company

Keyword: Alzheimers
Link ID: 27147 - Posted: 03.30.2020

By Julie Halpert As the coronavirus advances, it is taking a particularly harsh toll on the many who are caring for a loved one with dementia or Alzheimer’s, the most common form of dementia. According to a report by the Alzheimer’s Association, more than 16 million Americans are providing unpaid care for those with Alzheimer’s or other types of dementia. For them the virus is “really a double whammy,” said Lynn Friss Feinberg, a senior strategic policy adviser at AARP’s Public Policy Institute. “You’re worrying about your own health and that of your family member.” While the disease itself does not necessarily place patients at high risk for contracting the virus, they and their caregivers face a range of special challenges. Dementia patients are typically very sensitive to changes in routine and often require a great deal of hands-on care, both factors that are hard to manage now. Family members who usually rely on day care programs or visiting caregivers may be finding themselves with full-time responsibilities, while others whose loved ones are in facilities are unable to visit them now. Among the greatest challenges is how to minimize disruption in care that is intensely personal. “Care for dementia patients is ‘high touch,’” said Peter Lichtenberg, a professor of psychology and director of the Institute of Gerontology at Wayne State University. He recommends that caregivers take measures to avoid their own exposures by having provisions delivered, disinfecting surfaces and employing proper hand-washing techniques. K.C. Mehta has been caring for his wife, Sumi, since 2013, when she was given a diagnosis of Alzheimer’s at the age of 59. A former engineering executive at Chrysler, Mr. Mehta, who is 72 and lives in Rochester Hills, Mich., spends each day focused on maintaining his wife’s routine. Twice during the night, he changes her diaper. When she awakes, he bathes and dresses her. © 2020 The New York Times Company

Keyword: Alzheimers
Link ID: 27146 - Posted: 03.27.2020

Richard Masland The eye is something like a camera, but there is a whole lot more to vision than that. One profound difference is that our vision, like the rest of our senses, is malleable and modifiable by experience. Take the commonplace observation that people deprived of one sense may have a compensatory increase in others — for example, that blind people have heightened senses of hearing and touch. A skeptic could say that this was just a matter of attention, concentration and practice at the task, rather than a true sensory improvement. Indeed, experiments show that a person’s sensory acuity can achieve major improvement with practice. Yet with modern methodologies, neuroscientists have conclusively proved that the circuits of the brain neurons do physically change. Our senses are malleable because the sensory centers of the brain rewire themselves to strike a useful balance between the capacities of the available neural resources and the demands put on them by incoming sensory impressions. Studies of this phenomenon are revealing that some sensory areas have innate tendencies toward certain functions, but they show just as powerfully the plasticity of the developing brain. Take a rat that has been deprived of vision since birth — let’s say because of damage to both retinas. When the rat grows up, you train that rat to run a maze. Then you damage the visual cortex slightly. You ask the rat to run the maze again and compare its time before the operation and after. In principle, damaging the visual cortex should not do anything to the maze-running ability of that blind rat. But the classic experimental finding made decades ago by Karl Lashley of Yerkes Laboratories of Primate Biology and others is that the rat’s performance gets worse, suggesting that the visual cortex in the blind rat was contributing something, although we do not know what it was.­­ All Rights Reserved © 2020

Keyword: Vision; Development of the Brain
Link ID: 27143 - Posted: 03.25.2020

Jordana Cepelewicz In the 1990s, an army of clones invaded Germany. Within a decade, they had spread to Italy, Croatia, Slovakia, Hungary, Sweden, France, Japan and Madagascar — wreaking havoc in rivers and lakes, rice paddies and swamps; in waters warm and cold, acidic and basic. The culprits: six-inch-long, lobster-like creatures called marbled crayfish. Scientists suspect that sometime around 1995, a genetic mutation allowed a pet crayfish to reproduce asexually, giving rise to a new, all-female species that could make clones of itself from its unfertilized eggs. Deliberately or accidentally, some of these mutants were released from aquariums into the wild, where they rapidly multiplied into the millions, threatening native waterways species and ecosystems. But their success is strange. “All marbled crayfish which exist today derive from a single animal,” said Günter Vogt, a biologist at Heidelberg University. “They are all genetically identical.” Ordinarily, the absence of genetic diversity makes a population exceedingly vulnerable to the vagaries of its environment. Yet the marbled crayfish have managed to thrive around the globe. A closer look reveals that the crayfishes’ uniformity is only genome-deep. According to studies conducted by Vogt and others in the mid-2000s, these aquatic clones actually vary quite a bit in their color, size, behavior and longevity. Which means that something other than their genes is inspiring that diversity. Common sense tells us that if it’s not nature, it’s nurture: environmental influences that interact with an animal’s genome to generate different outcomes for various traits. But that’s not the whole story. New research on crayfish and scores of other organisms is revealing an important role for a third, often-overlooked source of variation and diversity — a surprising foundation for what makes us unique that begins in the first days of an embryo’s development: random, intrinsic noise. All Rights Reserved © 2020

Keyword: Development of the Brain; Genes & Behavior
Link ID: 27139 - Posted: 03.24.2020

By Amanda McCracken Over 30 years ago, Tom Johnson identified a gene that extended the very short life of a tiny roundworm, propelling him to the forefront of research on aging and raising the tantalizing possibility that aging could someday be slowed down in people, too. His work transformed the mind-set of scientists, launching a new field in the science of aging when he demonstrated that identifying and manipulating genes could lengthen life span. Although Johnson’s research has led to drug development to slow the effects of age-related diseases, he has yet to find the secret to stop aging. Now the soft-spoken redheaded scientist is running out of time as he confronts his own mortality. Five years ago, at age 66, work got confusing for Johnson, a professor in the Institute for Behavioral Genetics at the University of Colorado at Boulder. He found it impossible to keep track of his many projects. He began wondering whether he had Alzheimer’s like his newly diagnosed sister. He spoke to his wife, Vicki Simpson, about the little dogs he frequently saw running around the house (even though he knew they weren’t real). Simpson, a retired anesthesiologist, later learned such hallucinations are a trademark sign of Lewy body dementia. At first, she praised his imagination and then after several months suggested they visit a memory clinic. There he was diagnosed with probable Lewy body — a fatal disease with inescapable dementia that can be diagnosed with certainty only at death. Right now, there is no cure, only ways to ease symptoms.

Keyword: Alzheimers; Genes & Behavior
Link ID: 27134 - Posted: 03.23.2020

Peter Hess The coronavirus pandemic has shuttered universities and institutes, leaving scientists scrambling to continue their research. Hundreds of colleges and universities in the United States have dispatched students home and are aiming to transition to remote learning. Scientific organizations are canceling conferences or moving them online. And scientists have had to put research projects and clinical trials on hold. These decisions—all done with the intention of slowing the pandemic—may stall and stymie research, with long-term consequences for the field. It may also hurt career prospects for graduate students who rely on conference presentations to gain exposure. “From everything that we’re seeing, this isn’t like a two-week hiatus,” says Helen Egger, chair of the child and adolescent psychiatry department at NYU Langone Health in New York City. “We’re in the middle of the hurricane, and there’s no indication how much worse it’s going to get or when it will end.” One long-term benefit is that the crisis may give universities and professional organizations a crash course in embracing technology. “These types of experiences—as long as we are having them, unfortunately—are giving autism [researchers] and other researchers more skills to be able to have online conferences and online teaching as needed,” says Steven Kapp, lecturer in psychology at the University of Portsmouth in the United Kingdom. Backup plans: Some labs were prepared to meet the challenge, and they quickly put their emergency plans into place when news of the pandemic intensified. But, illustrating how rapidly the situation is changing, some of their plans derailed over the weekend. © 1986–2020 The Scientist

Keyword: Autism
Link ID: 27132 - Posted: 03.21.2020

By Adrienne Raphel Let me tell you a tale of two grandfathers, Irv and Murray. For decades, Irv, an introverted, quiet, retired bartender and former military engineer, had the same morning routine: coffee and cream; a roll; and the puzzle page of the Press of Atlantic City. He methodically and religiously worked his way through each one, from the crossword to the jumble to the cryptoquip, a substitution cipher that asks solvers to decode clues and figure out the pun. Extroverted and spontaneous Murray, a successful businessman and local politician, also had his morning routine: coffee with lots of sugar; oatmeal; and tinkering on one of his many writing projects, such as a loosely autobiographical musical about a traveling salesman. Murray swam a few times a week, devoured books and loved to travel. But he never did crosswords. Irv died at age 94, and he barely experienced any cognitive loss before the last six months of his life, when he exhibited rapid mental decline. Murray lived to be 91, but the last several years of his life were marked with severe dementia. When I was researching my book Thinking Inside the Box: Adventures with Crosswords and the Puzzling People Who Can’t Live Without Them, I was fascinated by my family’s case study. The evidence, it seemed, couldn’t be clearer: doing crosswords late in life prevents dementia. And at first, all the studies I found seemed to bear this hypothesis out. “Regular crosswords and number puzzles linked to sharper brain in later life,” a May 2019 Science Daily headline proclaims. According to a University of Exeter study, older adults who regularly did word and number puzzles had increased mental acuity. A 2011 experiment with members of the Bronx Aging Study found that a regular regimen of crosswords might delay the onset of cognitive decline. Belief in puzzle power has fueled multimillion-dollar industry of brain-training games like Lumosity or Dakim. © 2020 Scientific American,

Keyword: Alzheimers; Learning & Memory
Link ID: 27124 - Posted: 03.17.2020

By Linda Searing Alzheimer’s disease, the most common dementia among older adults, now affects about 5.8 million U.S. residents 65 and older — 10 percent of that age group, according to a new report from the Alzheimer’s Association. Age is considered the biggest risk factor for Alzheimer’s, with 3 percent of people 65 to 74, 17 percent of those 75 to 84 and 32 percent of people 85 and older — or nearly a third — having the disease. By 2050, the number of U.S. adults 65 and older with Alzheimer’s is expected to reach 13.8 million, with about half of them 85 or older. The association’s report attributes the growing number of Americans with Alzheimer’s to the projected aging of the U.S. population, with the West and Southeast regions of the country expected to experience the largest increases in the next five years. Sometimes, people under 65 develop what is called early-onset Alzheimer’s, but that is much less common. Although there is no known average age for the onset of Alzheimer’s, symptoms tend to be noticeable in the mid-60s, with memory issues typically one of the first signs. Alzheimer’s is an irreversible brain disorder that slowly destroys memory and thinking skills, can alter mood and personality and eventually disrupts the ability to carry out simple day-to-day tasks. Hallucinations, agitation and aggression are common symptoms as the condition advances. Although there is no cure for the disease — or even drugs to slow or stop progression — some medications can temporarily improve cognitive or behavioral symptoms. Non-medication therapies — exercise, music to stir recall or special lighting to ease sleep disorders — also can be helpful, but the report says that they also do not stop or slow the disease.

Keyword: Alzheimers
Link ID: 27123 - Posted: 03.17.2020

By Scott Barry Kaufman For many years, researchers have treated the individual traits and characteristics of autistic people as an enduring essence of their autism-- in isolation of the social context and without even asking autistic people what their social life is actually like. However, perspective matters. Who is to say it's autistic people who are the "awkward" ones? A number of myths about autistic people abound. For one, it's a great myth that autistic people lack empathy. This is how they were depicted for so many years in the clinical literature and in the media-- as emotionless, socially clueless robots. However, the more you get to know an autistic person, the more you realize just how caring they can be, even though they may have some difficulties reading social cues. As Steve Silberman points out, empathy is a two-way street. Another common misconception is that autistic people aren't social. I really like some recent approaches that add greater complexity to this issue, showing that when you take a contextual strengths-based approach you can see that people on the autism spectrum are much more social than researchers ever realized. The lens upon which we look at a person matters. As Megan Clark and Dawn Adams put it, "When autism is viewed through a deficit lens the strengths, positive attributes and interests of individuals on the spectrum can be overshadowed." In one recent study, Clark and Adams asked 83 children on the autism spectrum (aged 8 to 15 years) various questions about themselves. When asked "What do you like most about yourself?", the most common themes were "I am a good friend or person to be around" and "I am good at particular things."When asked "What do you enjoy the most?", one of the most endorsed themes was social interaction. © 2020 Scientific American

Keyword: Autism
Link ID: 27121 - Posted: 03.16.2020

Joanna Moorhead For artist and writer Charlotte Amelia Poe, 30, every day feels like a walk across a frozen pond. “It’s how it’s always been,” she explains. “You’re trying to navigate it and stay safe, but you’re aware that at any moment the ice is likely to crack, and at that point you will sink into the water.” The worst of it is that, when she feels that way, she has no idea how she can avoid going under. “You think you’re doing fine and you’re treading carefully enough not to crack the ice. But suddenly you’ve gone under. You’ve got it completely wrong – and you’ve no idea why.” Poe is describing how it feels to be autistic. She wants the rest of us to understand, she says, because it really matters, perhaps more than it’s ever mattered (of which more later). Her mission to break open the mystery of how it feels to be autistic has already been impressively successful: last year she won the Spectrum art prize for her video piece How To Be Autistic and recently she wrote a book of the same name. Her hope is that, by opening up about her own journey through childhood, school and adolescence, she can change other people’s perceptions and expectations about what autism is like, from the inside. We are talking in the sitting room of the semi-detached house overlooking a Suffolk field that Poe shares with three generations of her family. She has never left home and doesn’t expect to; her nephews and niece are playing outside in the garden, and one day their mother, her sister, will be her carer in the way that her parents are at the moment. © 2020 Guardian News & Media Limited

Keyword: Autism
Link ID: 27120 - Posted: 03.16.2020

As we get older, we become more easily distracted, but it isn't always a disadvantage, according to researchers. Tarek Amer, a psychology postdoctoral research fellow at Columbia University, says that although our ability to focus our attention on specific things worsens as we get older, our ability to take in broad swaths of information remains strong. So in general, older adults are able to retain information that a more focused person could not. For the last few years, Amer's research has focused mainly on cognitive control, a loose term that describes one's ability to focus their attention. His work at the University of Toronto, where he received his PhD in 2018, looked specifically at older adults aged 60 to 80. Amer joined Spark host Nora Young to discuss his research and how it could be implemented in practical ways. What happens to our ability to concentrate as we get older? There's a lot of research that shows as we get older, this ability tends to decline or is reduced with age. So essentially, what we see is that relative to younger adults, older adults have a harder time focusing on one thing while ignoring distractions. This distraction can be from the external world. This can also be internally based distractions, such as our own thoughts, which are usually not related to the task at hand. With respect to mind wandering specifically, the literature is ... mixed. [The] typical finding is that older adults tend to, at least in lab-based tasks, mind wander less. So I know that you've been looking, in your own research, at concentration and memory formation. So what exactly are you studying? One of the things I was interested in is whether this [decline in the ability to concentrate] could be associated with any benefits in old age. For example, one thing that we showed is that when older and younger adults perform a task that includes both task-relevant as well as task-irrelevant information, older adults are actually processing both types of information. So if we give them a memory task at the end that actually is testing memory for the irrelevant information … we see that older adults actually outperform younger adults. ©2020 CBC/Radio-Canada.

Keyword: Attention; Alzheimers
Link ID: 27116 - Posted: 03.14.2020

By Denise Grady Year after year for two decades, Nancy Wexler led medical teams into remote villages in Venezuela, where huge extended families lived in stilt houses on Lake Maracaibo and for generations, had suffered from a terrible hereditary disease that causes brain degeneration, disability and death. Neighbors shunned the sick, fearing they were contagious. “Doctors wouldn’t treat them,” Dr. Wexler said. “Priests wouldn’t touch them.” She began to think of the villagers as her family, and started a clinic to care for them. “They are so gracious, so kind, so loving,” she said. Over time, Dr. Wexler coaxed elite scientists to collaborate rather than compete to find the cause of the disorder, Huntington’s disease, and she raised millions of dollars for research. Her work led to the discovery in 1993 of the gene that causes Huntington’s, to the identification of other genes that may have moderating effects and, at long last, to experimental treatments that have begun to show promise. Now, at 74, Dr. Wexler is facing a painful and daunting task that she had long postponed. She has decided it’s time to acknowledge publicly that she has the disease she’s spent her life studying and that killed her mother, uncles and grandfather. “There is such stigma, and such ostracization,” Dr. Wexler, a professor of neuropsychology at the College of Physicians and Surgeons at Columbia University, said in a lengthy interview. “I think it’s important to destigmatize Huntington’s and make it not as scary. Of course it is scary. Having a fatal disease is scary and I don’t want to trivialize that. But if I can say, I’m not stopping my life, I’m going to work, we’re still trying to find a cure, that would help. If I can do anything to take the onus off having this thing, I want to do it.” Among her greatest concerns are the thousands of Venezuelans from the families full of the disease, whose willingness to donate blood and skin samples, and the brains of deceased relatives, made it possible to find the gene. But they live in an impoverished region, and, Dr. Wexler said, they are still outcasts. The clinic that she and her colleagues opened has been shut down by Venezuela’s government. © 2020 The New York Times Company

Keyword: Huntingtons; Genes & Behavior
Link ID: 27110 - Posted: 03.10.2020

By Perri Klass, M.D. When you talk about sibling issues, everyone takes it personally. Whether it’s birth order and the supposed advantages of being the oldest (or youngest, or middle), or the question of having (or being) the favorite child, people tend to respond immediately with their own sometimes very individual and emotional stories. What I want to talk about today are sibling sex ratios — having a sibling of the other sex versus growing up in all-boy or all-girl sibling configurations. The most evocative phrase I’ve seen for this is “family constellations,” which I like because it suggests that there are lots of interesting — and even beautiful — arrangements, but that differences are real. But let’s take one step further back: Are there actually parents, or parent pairs, who are more likely to conceive boys or girls? Does the five-daughter family (from “Pride and Prejudice” or “Fiddler on the Roof”) or the seven-son setup (“Seven Brides for Seven Brothers”) just reflect five (or seven) random rolls of the dice, or is there actually something going on from an evolutionary point of view? The evolutionary theory, which has been advanced to explain sex ratio, goes back to Darwin, but was fully formulated in 1930 by a British scientist named Ronald Fisher, who made the argument that if individuals vary in the sex ratio among their offspring (that is, some are more likely to produce more males or more females), the reproductive advantage in a population will always lie with the rarer sex, and thus the sex ratio will equilibrate toward 1:1. After all, Fisher argued, half of the genetic material of the next generation must come by way of those who tend to produce males, and half from those who tend to produce females. But are there such tendencies? I’ve heard people say that having boys “runs in the family,” or that their cousins are almost all girls, that’s the “family pattern.” But a very large study of 4.7 million births in Sweden published in February in the journal Proceedings of the Royal Society argues that there is no evidence of a genetic tendency toward one sex or the other, or a family tendency. © 2020 The New York Times Company

Keyword: Development of the Brain; Sexual Behavior
Link ID: 27108 - Posted: 03.10.2020

Amelia Hill A low carbohydrate diet may prevent and even reverse age-related damage to the brain, research has found. By examining brain scans, researchers found that brain pathways begin to deteriorate in our late 40s – earlier than was believed. “Neurobiological changes associated with ageing can be seen at a much younger age than would be expected, in the late 40s,” said Lilianne R Mujica-Parodi, a professor in the department of biomedical engineering at Stony Brook University in New York. “However, the study also suggests that this process may be prevented or reversed based on dietary changes that involve minimising the consumption of simple carbohydrates,” added Mujica-Parodi. To better understand how diet influences brain ageing, researchers concentrated on young people whose brains showed no signs of ageing. This is the period during which prevention may be most effective. Using brain scans of nearly 1,000 individuals between the ages of 18 to 88, researchers found that the damage to neural pathways accelerated depending on where the brain was getting its energy from. Glucose, they found, decreased the stability of the brain’s networks while ketones – produced by the liver during periods of carbohydrate restrictive diets – made the networks more stable. “What we found with these experiments involves both bad and good news,” said Mujica-Parodi, “The bad news is that we see the first signs of brain ageing much earlier than was previously thought. “However, the good news is that we may be able to prevent or reverse these effects with diet … by exchanging glucose for ketones as fuel for neurons,” she added in the study, which is published in PNAS. © 2020 Guardian News & Media Limited

Keyword: Alzheimers; Obesity
Link ID: 27103 - Posted: 03.07.2020

By Nicholas Bakalar Moderate alcohol consumption is associated with reduced levels of beta amyloid, the protein that forms the brain plaques of Alzheimer’s disease, a new study suggests. Korean researchers studied 414 men and women, average age 71, who were free of dementia or alcohol-related disorders. All underwent physical exams, tests of mental acuity, and PET and M.R.I. scans. They were carefully interviewed about their drinking habits. The study, in PLOS Medicine, measured drinking in “standard drinks” — 12 ounces of beer, five ounces of wine, or one-and-a-half ounces of hard liquor. Compared with abstainers, those who drank one to 13 standard drinks a week had a 66 percent lower rate of beta amyloid deposits in their brains. The results applied only to those who drank moderately for decades, and not to those who recently began drinking moderately or drank more than 13 drinks a week. The study controlled for age, sex, education, socioeconomic status, body mass index, vascular health and many other factors. Dr. Dong Young Lee, the senior author and a professor of psychiatry at Seoul National University College of Medicine, cautioned that this was an observational study that looked at people at one point in time, and does not prove cause and effect. Still, he said, “In people without dementia and without alcohol abuse or dependency, moderate drinking appears to be helpful as far as brain health is concerned.” © 2020 The New York Times Company

Keyword: Alzheimers; Drug Abuse
Link ID: 27096 - Posted: 03.06.2020

By David H. Freedman Two levels below ground, under a small, drab building at the University of Bonn, is a wall of cages containing mice that, according to standard tests, are extraordinarily average. They learn and remember how to run mazes no better nor worse than other mice. It takes them a typical amount of time to figure out how to extricate themselves from a tank of water with hidden exit steps. There’s nothing out of line about how they interact with other mice, nor their willingness to explore open spaces. And yet these mice are the center of attention at the lab of Andreas Zimmer. That’s because their boringly average minds may well hold the key to beating Alzheimer’s and elderly dementia. Many of the mice are 18 months old, roughly equivalent to a 70-year-old human. Mice normally start to show mental decline at around a year old, and by 18 months, struggle with mazes and other mental tasks, as well as with socializing. But not these rodent seniors. “You can’t tell the difference between them and two-month-old mice,” says Zimmer. Even more surprising is what Zimmer has done to get these elderly mice remembering and behaving like younger ones. It’s not special genes, a particular training regimen, nor an unusual diet. They don’t get any approved memory drug, nor a new investigational procedure. Basically, Zimmer keeps them very slightly stoned. A longtime U.S. National Institutes of Health (NIH) researcher who is now one of Germany’s most respected neuroscientists, Zimmer has been on a long journey to answer a question that few researchers had thought to ask: Is it possible that weed, long seen as the stuff of slackers, might actually contain the secret to sharpening the aging brain? © 2020 Kalmbach Media Co.

Keyword: Alzheimers; Drug Abuse
Link ID: 27094 - Posted: 03.05.2020