Chapter 5. Hormones and the Brain
Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.
By NATALIE ANGIER VIEWED superficially, the part of youth that the psychologist Jean Piaget called middle childhood looks tame and uneventful, a quiet patch of road on the otherwise hairpin highway to adulthood. Said to begin around 5 or 6, when toddlerhood has ended and even the most protractedly breast-fed children have been weaned, and to end when the teen years commence, middle childhood certainly lacks the physical flamboyance of the epochs fore and aft: no gotcha cuteness of babydom, no secondary sexual billboards of pubescence. Yet as new findings from neuroscience, evolutionary biology, paleontology and anthropology make clear, middle childhood is anything but a bland placeholder. To the contrary, it is a time of great cognitive creativity and ambition, when the brain has pretty much reached its adult size and can focus on threading together its private intranet service — on forging, organizing, amplifying and annotating the tens of billions of synaptic connections that allow brain cells and brain domains to communicate. Subsidizing the deft frenzy of brain maturation is a distinctive endocrinological event called adrenarche (a-DREN-ar-kee), when the adrenal glands that sit like tricornered hats atop the kidneys begin pumping out powerful hormones known to affect the brain, most notably the androgen dihydroepiandrosterone, or DHEA. Researchers have only begun to understand adrenarche in any detail, but they see it as a signature feature of middle childhood every bit as important as the more familiar gonadal reveille that follows a few years later. © 2011 The New York Times Company
By Scicurious Hi. In a few minutes I’d like you to stand up and give a short public speech to a judgmental group of people. The speech will be about the current national and international effects of Marbury v Madison, with particular focus on violations of interstate commerce. You have 15 minutes to prepare and the speech will have to be 15 minutes long. I hope you’ve done your research. Nervous yet? If you are, you’re not alone. Fear of public speaking (glossophobia, or just stage fright) is one of the most common fears in the Western world. But it’s ok. We’re going to have you sit with your loved one, who will be able to give you encouragement as you prepare. Do you feel a little bit better? I bet you do. But do you really, actually feel better? Does your body react to stress differently when you’ve got a loved one with you to help you out? It turns out that it might. At least, if you’ve got a specific kind of oxytocin receptor gene. Oxytocin gets a lot of press. And well it should. Recent findings on oxytocin have shown effects on trust, on generosity, on behaviors in austistic children even. Not to mention all the effects that oxytocin has on parental bonding and on your sex life. While many of these studies have looked at levels of circulating oxytocin, or the effects of giving oxytocin (usually as a nasal spray) on behavior, people have recently started to look at the other side of oxytocin: the oxytocin receptor. © 2011 Scientific American,
By Bella English Jonas and Wyatt Maines were born identical twins, but from the start each had a distinct personality. Jonas was all boy. He loved Spiderman, action figures, pirates, and swords. Wyatt favored pink tutus and beads. At 4, he insisted on a Barbie birthday cake and had a thing for mermaids. On Halloween, Jonas was Buzz Lightyear. Wyatt wanted to be a princess; his mother compromised on a prince costume. Once, when Wyatt appeared in a sequin shirt and his mother’s heels, his father said: “You don’t want to wear that.’’ “Yes, I do,’’ Wyatt replied. “Dad, you might as well face it,’’ Wayne recalls Jonas saying. “You have a son and a daughter.’’ That early declaration marked, as much as any one moment could, the beginning of a journey that few have taken, one the Maineses themselves couldn’t have imagined until it was theirs. The process of remaking a family of identical twin boys into a family with one boy and one girl has been heartbreaking and harrowing and, in the end, inspiring — a lesson in the courage of a child, a child who led them, and in the transformational power of love. Wayne and Kelly Maines have struggled to know whether they are doing the right things for their children, especially for Wyatt, who now goes by the name Nicole. Was he merely expressing a softer side of his personality, or was he really what he kept saying: a girl in a boy’s body? Was he exhibiting early signs that he might be gay? Was it even possible, at such a young age, to determine what exactly was going on? © 2011 The New York Times Company
Prenatal steroids — given to pregnant women at risk for giving birth prematurely — appear to improve survival and limit brain injury among infants born as early as the 23rd week of pregnancy, according to a study by a National Institutes of Health research network. Current guidelines recommend giving prenatal steroids to women at risk of delivering between the 24th and 34th weeks of pregnancy. "These findings provide strong evidence that prenatal steroids can benefit infants born as early as the 23rd week of pregnancy," said study author Rosemary D. Higgins, M.D., of the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). The study was conducted by researchers participating in the NICHD Neonatal Research Network and led by Waldemar A. Carlo, director of the Division of Neonatology at the University of Alabama at Birmingham. The findings appear in the Dec. 7 Journal of the American Medical Association. When given to pregnant woman at risk for preterm delivery, steroid hormones help the fetus's lungs to mature. For infants born preterm, increased lung development improves the chances for survival and may decrease the risk of brain injury. Infants born in the 22nd through the 25th week of pregnancy — far earlier than the 40 weeks of a full term pregnancy — are the smallest, most frail category of newborns. Many die soon after birth, despite the best attempts to save them, including the most sophisticated newborn intensive care available. Some survive, and reach adulthood relatively unaffected. The rest will experience some degree of lifelong disability, including minor hearing loss, cerebral palsy, and intellectual disability.
By Tim Wall A review of 142 studies on the effects of the herbicide atrazine had bad news for testes. "Essentially, atrazine chemically castrates animals. When you look at a male exposed to atrazine, the testes are missing sperm," Tyrone Hayes of the University of California, Berkeley told Discovery News. The effects of atrazine on male development are consistent across all examined animals, found a study published by a team of 22 researchers from more than 60 nations in the Journal of Steroid Biochemistry and Molecular Biology. Mammals, reptiles, and fish were all affected, but amphibians caught the worst of it. In a study by Hayes, male African clawed frogs turned into females after exposure to atrazine, which kills weeds around the world in everything from corn fields to orchards. "And this is not at extremely high concentrations" said co-author of the review Val Beasley of the University of Illinois in a press release. "These are at concentrations that are found in the environment." Humans aren't spared the effects of atrazine, the world's second most common herbicide after glyphosate, Hayes said. Hayes pointed to studies correlating atrazine exposure to low sperm quality, birth defects, miscarriage, and breast cancer © 2011 Discovery Communications, LLC.
By HARRIET BROWN In patients with depression, anxiety and other psychiatric problems, doctors often find abnormal blood levels of thyroid hormone. Treating the problem, they have found, can lead to improvements in mood, memory and cognition. Now researchers are exploring a somewhat controversial link between minor, or subclinical, thyroid problems and some patients’ psychiatric difficulties. After reviewing the literature on subclinical hypothyroidism and mood, Dr. Russell Joffe, a psychiatrist at the North Shore-Long Island Jewish Health System, and colleagues recently concluded that treating the condition, which affects about 2 percent of Americans, could alleviate some patients’ psychiatric symptoms and might even prevent future cognitive decline. Patients with psychiatric symptoms, Dr. Joffe said, “tell us that given thyroid hormones, they get better.” The thyroid, a bow-tie-shaped gland that wraps around the trachea, produces two hormones: thyroxine, or T4, and triiodothyronine, known as T3. These hormones play a role in a surprising range of physical processes, from regulation of body temperature and heartbeat to cognitive functioning. Any number of things can cause the thyroid to malfunction, including exposure to radiation, too much or too little iodine in the diet, medications like lithium, and autoimmune disease. And the incidence of thyroid disease rises with age. Too much thyroid hormone (hyperthyroidism) speeds the metabolism, causing symptoms like sweating, palpitations, weight loss and anxiety. Too little (hypothyroidism) can cause physical fatigue, weight gain and sluggishness, as well as depression, inability to concentrate and memory problems. © 2011 The New York Times Company
by Catherine de Lange How kind you are could be affected by a change in a single gene. What's more, others can tell if you have the gene even if you don't speak a single word. There are several variations of the gene that codes for the receptor for the hormone oxytocin. Aleksandr Kogan at the University of Toronto, Canada, and colleagues wanted to check whether these variations influence behaviour, since high levels of oxytocin are believed to make people more sociable. Kogan's team asked 116 volunteers to watch 23 silent videos that were 20 seconds long. Each showed a person's response to their partner telling them a story of personal suffering. The volunteers were asked to rate how kind and trustworthy the person in the video appeared to be. People with the so-called GG version of the oxytocin receptor gene were judged to be kinder than those with GA or AA versions. The difference? Those with GG variations used significantly more non-verbal empathetic gestures in their storytelling such as smiling and nodding. Kogan expects that this is what influenced the observers' judgements. Further research will be needed to identify the effect of the different genetic variations on oxytocin levels. Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.111265810 © Copyright Reed Business Information Ltd.
By Tina Hesman Saey Researchers have grown a mouse pituitary gland for the first time from embryonic stem cells. Or rather, the pituitary gland grew itself, after Japanese researchers coaxed embryonic stem cells to form the type of tissues that normally surround the gland. The accomplishment, reported online November 9 in Nature, could be the first step toward replacement pituitary glands for people. Self-made glands growing in lab dishes may also help researchers learn how the organs develop inside the body. “There’s a lot in it to be excited about, whether you’re a developmental biologist or interested in clinical applications,” says Sally Camper, a developmental geneticist at the University of Michigan in Ann Arbor. Camper has tried, and failed, to coax embryonic stem cells to form pituitary glands. “It’s a gorgeous piece of work, and it’s just really, really exciting,” she says. Scientists have persuaded stem cells to form particular types of tissues before, but growing a whole organ in a lab dish has been an elusive goal, says pediatric endocrinologist Mehul Dattani of the University College London Institute of Child Health and Great Ormond Street Hospital for Children in London. What allowed Yoshiki Sasai of the RIKEN Center for Developmental Biology in Kobe, Japan, and colleagues to succeed where others have failed is that the group recreated conditions that exist in the part of the brain where the pituitary normally grows. © Society for Science & the Public 2000 - 2011
By Dina ElBoghdady, A chemical used widely in plastic bottles, metal cans and other consumer products could be linked to behavioral and emotional problems in toddler girls, according to a government-funded study published online Monday in the journal Pediatrics. After tracking 244 Cincinnati-area mothers and their 3-year-olds, the study concluded that mothers with high levels of bisphenol A (BPA) in their urine were more likely to report that their children were hyperactive, aggressive, anxious, depressed and less in control of their emotions than mothers with low levels of the chemical. While several studies have linked BPA to behavioral problems in children, this report is the first to suggest that a young girl’s emotional well-being is linked to her mother’s exposure during pregnancy rather than the child’s exposure after birth. Girls were more sensitive to the chemical in the womb than boys, maybe because BPA mimics the female hormone estrogen, which is thought to play a role in behavioral development. The results add to a growing body of research that suggests exposure to BPA poses health risks in humans. While the federal government has long maintained that low doses of BPA are safe, the Food and Drug Administration and other federal agencies are taking a closer look and investing in more research about the chemical’s health effects. © 1996-2011 The Washington Post
Multiple sclerosis might be connected to a lack of steroids in the brain, Alberta researchers have found. MS attacks the brain and spinal cord, causing inflammation and damage that can lead to paralysis and sometimes blindness. In the September issue of the journal Brain, neurologist Dr. Chris Power of the University of Alberta Hospital in Edmonton and his colleagues describe a new potential avenue for treating MS. There are some drugs related to neurosteroids that are actively in clinical trials, Dr. Chris Power said.There are some drugs related to neurosteroids that are actively in clinical trials, Dr. Chris Power said. CBC The discovery centres on neurosteroids, which help brain cells to talk, grow and repair themselves. The findings open up a brain process "that we might be able to direct so that we can prevent damage and maybe even repair the damaged brain," Power said Wednesday. Brains of people who died with multiple sclerosis showed lower levels of neurosteroids, the researchers found. The team believes that by replacing neurosteroids, it might be possible to alleviate symptoms or even prompt recovery, based on the results of their test tube and mouse modeling studies. "We've actually jumped the queue a little bit because there are some drugs related to neurosteroids that are actively in clinical trials," Power said. "This certainly provides fertile ground." © CBC 2011
by Marianne English Though research has shown that women are more likely than men to remember the emotional details of an event, there may be another dividing factor when it comes to memory: birth control. Scientists know people's hormones shape how their memories form. For instance, our fight-or-flight hormones influence how the brain encodes a specific memory, with traumatic events making more of an impact than everyday activities. A portion of the brain called the amygdala works on the receiving end of these hormones and is thought to play a central role in making and storing new memories. Birth control works by reducing the amount of estrogen and progesterone in a woman's body to limit ovulation, but it's unclear whether these hormones affect how a person recalls an event. In one study, researchers looked at whether women taking oral contraceptives remembered events from an experiment differently than women with normal menstrual cycles not on birth control. Seventy-two female subjects were recruited for the study, half on the pill and half not. Each group watched variations of a slide show story that involved a young boy being hit by a car. Before and throughout the slide show, researchers collected saliva samples to measure alpha-amylase -- a chemical that signifies a drop or rise in the fight-or-flight hormone norepinephrine, which increases a person's heart rate during emergencies or stressful situations. © 2011 Discovery Communications, LLC.
by Elizabeth Norton Humans are probably the only species on Earth who nurture their young for 20 years or more. For men in particular, the intensive demands of parenting can come as such a shock that a built-in biological mechanism has evolved to help cope with the change. A new study shows that becoming a father leads to a sharp decline in testosterone, suggesting that although high levels of the hormone may help men win a mate, testosterone-fueled traits such as aggression and competition are less useful when it comes to raising children. Previous research had shown that among new fathers, testosterone levels were lower than in men of the same age who didn't have children. But no study addressed whether parenthood itself was responsible, or whether men who became committed partners and fathers started out with lower levels of the hormone than did their single, footloose friends. To sort out cause and effect, anthropologists Lee Gettler, Christopher Kuzawa, and colleagues at Northwestern University in Evanston, Illinois, and the University of San Carlos in Cebu City, Philippines, checked testosterone levels in a group of men participating in the ongoing Cebu Longitudinal Health and Nutrition Survey. The survey began with a group of some 3000 women who were pregnant in 1983 and followed the general health, nutrition, medical care, and survival of their children; it has since expanded into an intergenerational study of health, education, and sexual behavior as those children grew up and are now having children of their own. © 2010 American Association for the Advancement of Science.
by Sarah C. P. Williams Dracula may have had it right: Young blood can restore an aging body. Scientists have discovered that blood from a 3-month-old mouse can coax the brain of an older mouse into making new brain cells. The team has not yet identified the rejuvenating factor, but they have found a blood-borne compound that seems to promote brain aging. As the body ages, the brain gradually becomes more sluggish. Even in people lucky enough to dodge neurodegenerative disorders such as Alzheimer's disease, fewer new neurons are created from stem cells in the brain, and the activity of existing neurons weakens. Neuroscientist Tony Wyss-Coray of Stanford University School of Medicine in Palo Alto, California, suspected that the changes could be mediated by factors in the blood. Previous research has shown that giving young blood to older mice boosts their immune system and muscle function. Wyss-Coray wondered whether the same might be true in the brain. Although the so-called blood-brain barrier blocks many large molecules from entering the brain from the bloodstream, the barrier isn't sealed tight everywhere, which might allow some compounds to get through. It's leakiest at places where there are brain stem cells, suggesting that these neuron precursors may have interaction with the circulatory system. Wyss-Coray's team measured neurogenesis, the creation of new neurons from stem cells, in mice that were 3 months old and mice that were almost 2 years old and considered adults. Then they surgically connected the circulatory systems of pairs of young and old mice. The number of new cells in one region of the brain's hippocampus, related to memory formation, went from fewer than 400 to almost 1000 in the older mice. In the younger mice, it dropped by almost a quarter. © 2010 American Association for the Advancement of Science
By Victoria Gill Science reporter, BBC Nature Female yellow-bellied marmots that have many male litter-mates become "tom boys", according to a study of these big, playful rodents. Developing males produce testosterone, which circulates in the mother's uterus; this male sex hormone "masculinises" the females. The phenomenon has been seen in many species, but this study shows its long-term impact on animal behaviour. The findings are published in the Royal Society journal Biology Letters. Lead researcher Raquel Monclus explained that the results emerged from a 50-year study of the marmots in the Rocky Mountain Biological Laboratory, Colorado. "We have data from generations of these animals that the lab has gathered," Dr Monclus told BBC Nature. She carried out the study while at the University of California, Los Angeles, and is now based at the UAM (Universidad Autonoma de Madrid) in Spain. The physical effects of testosterone were apparent early in this ongoing study, as it was much more difficult for the researchers to correctly identify the sex of newborn females from litters that were mostly male. BBC © 2011
by Cian O'Luanaigh Here's a piece of good news for people who have had a gastric bypass – not only will you eat less, you may also start to eat more healthily. The most common form of bariatric – anti-obesity – surgery is the "Roux-en-Y" gastric bypass, which involves stapling the stomach so a small pouch is made at the top, which is then connected directly to the small intestine. This bypasses most of the stomach and the duodenum so the patient feels full quicker. The vertical-banded gastroplasty is an alternative technique which reduces the volume of the stomach without bypassing any part of the intestine, restricting how much the patient can eat at any one time. After people undergo gastric bypass operations, it is not uncommon for them to report that their eating habits have changed. To investigate these claims, Carel le Roux and colleagues from Imperial College London asked 16 people who had undergone either type of bariatric surgery six years before to fill in a survey about their dietary preferences after the operation. People who had had a gastric bypass reported eating a lower proportion of fat after surgery than those with a vertical-banded gastroplasty. To find out why this was so, the team carried out either a gastric bypass or a sham operation on 26 rats. © Copyright Reed Business Information Ltd.
THERE was at least one downside to Farinelli's castration. The operation may have preserved the 18th-century singer's treble voice into adulthood, making him a musical legend, but it also condemned him to a skull deformity that may have affected his mind. Farinelli was exhumed in 2006 so that his skeleton could be studied. Lead investigator Maria Giovanna Belcastro of the Alma Mater Studiorum University of Bologna, Italy, was able to identify two unusual features. Like those of other castrati, Farinelli's limb bones were unusually long. And the front of his skull had grown inwards in a lumpy mass, in places twice as thick as unaffected bone (Journal of Anatomy, DOI: 10.1111/j.1469-7580.2011.01413.x). This is called hyperostosis frontalis interna (HFI). It is thought to be caused by hormonal disorders, particularly too much oestrogen, which explains why it is normally found in post-menopausal women and is rare in men. HFI was thought to be harmless, says Israel Hershkovitz of Tel Aviv University in Israel, but is now linked to behavioural disorders, headaches and neurological diseases like Alzheimer's. Though any such symptoms probably would not have affected Farinelli until late in life, Hershkovitz says. © Copyright Reed Business Information Ltd.
By Nathan Seppa A nutritional supplement that is free of charge, offers a wide range of health benefits and poses little risk sounds like fodder for a late-night TV commercial. But proponents of vitamin D are increasingly convinced that the sunshine vitamin delivers the goods, no strings attached. It offers a safe route to better health, these advocates say, by promoting proper function of the bones, heart, brain, immune system, you name it. Yet, the proponents claim, most people don’t get enough. Whereas humans’ prehistoric ancestors lived outdoors and made oodles of vitamin D in their sun-exposed skin, people today have become shut-ins by comparison — and scant sun exposure means low vitamin D. Of course, not everyone sees such a grand reach for the vitamin. While scientists concur that it is essential for bone maintenance, some stop right there. The skeptics note that vitamin D’s other promising qualities have shown up largely in studies that fall short of the gold standard of medicine — the randomized controlled trial, in which groups of people get either a placebo or the real thing. While a handful of randomized trials have shown additional benefits, others have not, leaving a gap in the vitamin’s otherwise sterling reputation. This debate came to a head last November, when an Institute of Medicine panel of scientists announced new vitamin D recommendations. The old intake levels were barely high enough to prevent rickets, a bone condition associated with the Industrial Revolution. The IOM panel boosted the recommended daily intake of the vitamin from 200 to 600 international units per day for most of the population. The new dose is about 15 micrograms, in the range of vitamin D found in most multivitamins. © Society for Science & the Public 2000 - 2011
By Janet Raloff An ingredient in many clear plastics also renders some gender-linked behaviors plastic, at least in mice. Two new studies link feminized behaviors in adult males with exposures during development to bisphenol A, a weak estrogen-mimicking chemical. In one study, some behaviors in BPA-exposed females morphed into features characteristic of males. The findings come from laboratory studies conducted in different species. Each experiment also exposed animals at a different time during development — one from the womb through weaning, the other during the rodent equivalent of adolescence and early adulthood. The trials therefore identify different periods during which the brain appears vulnerable to pollutants that mimic or alter the activity of sex hormones. Because early BPA exposures left no lasting changes in sex hormone levels, the authors of each study note, the behavioral changes they observed in adulthood probably trace to an earlier rewiring of brain circuitry — most likely in an area known as the hippocampus. Cheryl Rosenfeld of the University of Missouri–Columbia and her colleagues added BPA to the chow they fed to pregnant deer mice. BPA concentrations in the moms peaked at around 9 nanograms per milliliter, Rosenfeld says, “which is in the range of what’s been measured in humans.” © Society for Science & the Public 2000 - 2011
by Elizabeth Norton Life for those with a genetic disease called Prader-Willi syndrome, which affects an estimated one out of 15,000 people, can be challenging both for the patient and his or her family. Sufferers have an insatiable hunger that can lead to life-threatening obesity if access to food is not restricted. And worse, they have behavioral problems akin to autism. Tantrums and tears are common because these patients have difficulty understanding the motives of others and controlling their own emotions. But treatment with the brain hormone oxytocin may help bring both emotions and eating into balance, according to a new study. Several clues pointed to the potential of oxytocin, often thought of as the "trust hormone." Research conducted on the brain tissue donated after death from Prader-Willi patients showed that the hypothalamus (the body's thermostat) has abnormalities in the nerve cells that produce this hormone. Moreover, the hypothalamus releases oxytocin in response to touching, social interactions, relaxation, and trust—all the things people with Prader-Willi syndrome have trouble with. And oxytocin treatments have improved the social skills of autistic patients. Finally, the hormone is thought to contribute to feelings of fullness after eating, "satiety" in scientific parlance. To see whether oxytocin could benefit individuals with Prader-Willi syndrome, endocrinologist Maïthé Tauber of the Children's Hospital in Toulouse, France, and colleagues injected oxytocin or a placebo into the noses of 24 adult patients. The researchers monitored the patients' behavior; they also used cartoon stories to test patients' grasp of social interactions and pictures of faces to see how well they could recognize emotions. © 2010 American Association for the Advancement of Science
By KATHRYN HARRISON Readers who can’t identify Jean-Martin Charcot as the name of the French neurologist whose 19th-century experiments with hypnosis influenced Sigmund Freud’s theory of neurosis may yet recognize the work he conducted at the Saltpêtrière Hospital in Paris. Photographs and illustrations of Charcot’s patients, all women suffering hysteria, remain in currency today, 140 years after they were made, if more as curiosities than as clinically valuable documents. Once seen, these images — of, for example, a woman wearing little more than a tangle of bed sheets, her eyes rolled up into her head in either “ecstasy” or “delirium,” or fixed on the invisible object of her “amorous supplication” — are not easily forgotten, let alone dismissed. Poses classified as “passionate attitudes,” they have the disquieting aspect of pornography masquerading as intellectual inquiry. Charcot, as portrayed in Asti Hustvedt’s consistently enthralling “Medical Muses,” focused intently — myopically, one could argue — on using hypnosis to induce hysteria and make “his hysterics, with their bizarre fits and spasms, into ideal medical specimens.” But the provocative behavior of those “specimens” transformed Saltpêtrière into something closer to a carnival than a teaching hospital. As much showman as physician, Charcot gave weekly two-hour lectures to a packed amphitheater, including demonstrations designed to captivate an audience accustomed to staged séances and exhibitions of mesmerism or telepathy. One of Charcot’s students described the dramatic potential of exhibiting hypnotized women: “We can cut them, prick them and burn them, and they feel nothing.” © 2011 The New York Times Company
Keyword: Hormones & Behavior
Link ID: 15460 - Posted: 06.20.2011