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

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By Adrian Cho Whether they're from humans, whales, or elephants, the brains of many mammals are covered with elaborate folds. Now, a new study shows that the degree of this folding follows a simple mathematical relationship—called a scaling law—that also explains the crumpling of paper. That observation suggests that the myriad forms of mammalian brains arise not from subtle developmental processes that vary from species to species, but rather from the same simple physical process. In biology, it rare to find a mathematical relationship that so tightly fits all the data, say Georg Striedter, a neuroscientist at the University of California, Irvine. "They've captured something," he says. Still, Striedter argues that the scaling law describes a pattern among fully developed brains and doesn't explain how the folding in a developing brain happens. The folding in the mammalian brain serves to increase the total area of the cortex, the outer layer of gray matter where the neurons reside. Not all mammals have folded cortices. For example, mice and rats have smooth-surfaced brains and are "lissencephalic." In contrast, primates, whales, dogs, and cats have folded brains and are "gyrencephalic." For decades, scientists have struggled to relate the amount of folding in a species' brain to some other characteristic. For example, although animals with tiny brains tend to have smooth ones, there is no clean relationship between the amount of folding—measured by the ratio of the total area of the cortex to the exposed outer surface of the brain—and brain mass. Make a plot of folding versus brain mass for various species and the data points fall all over and not on a unified curve. Similarly, there is no clean relationship between the amount of folding and the number of neurons, the total area of the cortex, or the thickness of the cortex. © 2015 American Association for the Advancement of Science

Keyword: Development of the Brain; Evolution
Link ID: 21133 - Posted: 07.04.2015

By SINDYA N. BHANOO It may be possible to diagnose autism by giving children a sniff test, a new study suggests. Most people instinctively take a big whiff when they encounter a pleasant smell and limit their breathing when they encounter a foul smell. Children with autism spectrum disorder don’t make this natural adjustment, said Liron Rozenkrantz, a neuroscientist at the Weizmann Institute of Science in Israel and one of the researchers involved with the study. She and her colleagues report their findings in the journal Current Biology. They presented 18 children who had an autism diagnosis and 18 typically developing children with pleasant and unpleasant odors and measured their sniff responses. The pleasant smells were rose and soap, and the unpleasant smells were sour milk and rotten fish. Typically developing children adjusted their sniffing almost immediately — within about 305 milliseconds. Children with autism did not respond as rapidly. As they were exposed to the smells, the children were watching a cartoon or playing a video game. “It’s a semi-automated response,” Ms. Rozenkrantz said. “It does not require the subject’s attention.” Using the sniff test alone, the researchers, who had not been told which children had autism, were able to correctly identify those with autism 81 percent of the time. They also found that the farther removed an autistic child’s sniff response was from the average for typically developing children, the more severe the child’s social impairments were. © 2015 The New York Times Company

Keyword: Autism; Chemical Senses (Smell & Taste)
Link ID: 21129 - Posted: 07.04.2015

Nancy Shute Powerful antipsychotic medications are being used to treat children and teenagers with ADHD, aggression and behavior problems, a study finds, even though safer treatments are available and should be used first. "There's been concern that these medications have been overused, particularly in young children," says Mark Olfson, a professor of psychiatry at Columbia University who led the study. It was published Wednesday in JAMA Psychiatry. "Guidelines and clinical wisdom suggest that you really should be using a high degree of caution and only using them when other treatments have failed, as a last resort." Olfson and his colleagues looked at prescription data from about 60 percent of the retail pharmacies in the United States in 2006, 2008 and 2010. That included almost 852,000 children, teenagers and young adults. Teens were most likely to be prescribed antipsychotics, with 1.19 percent getting the drugs in 2010, compared to 0.11 percent in younger children. Boys were more likely to be given the medications. Antipsychotic medications like clozapine and olanzapine are used to treat schizophrenia, bipolar disorder and some symptoms of autism. They have not been approved by the Food and Drug Administration to treat aggression and ADHD, but are prescribed off label to reduce disruptive behavior. FDA Debates Safety Of Antipsychotic Drugs In Kids Use of antipsychotics in children has been questioned because the drugs can have serious side effects, including tremors, weight gain, increased diabetes risk and elevated cholesterol. © 2015 NPR

Keyword: Drug Abuse; Development of the Brain
Link ID: 21122 - Posted: 07.02.2015

Boys are more likely than girls to receive a prescription for antipsychotic medication regardless of age, researchers have found. Approximately 1.5 percent of boys ages 10-18 received an antipsychotic prescription in 2010, although the percentage falls by nearly half after age 19. Among antipsychotic users with mental disorder diagnoses, attention deficit hyperactivity disorder (ADHD) was the most common among youth ages 1-18, while depression was the most common diagnosis among young adults ages 19-24 receiving antipsychotics. Despite concerns over the rising use of antipsychotic drugs to treat young people, little has been known about trends and usage patterns in the United States before this latest research, which was funded by the National Institute of Mental Health (NIMH), part of the National Institutes of Health. Mark OlfsonExternal Web Site Policy, M.D., M.P.H., of the Department of Psychiatry, College of Physicians and Surgeons and Columbia University and New York State Psychiatric Institute, New York City, and colleagues Marissa King, Ph.D., Yale, New Haven, Connecticut, and Michael Schoenbaum, Ph.D., NIMH, report their findings on July 1 in JAMA Psychiatry. “No prior study has had the data to look at age patterns in antipsychotic use among children the way we do here,” said co-author Michael Schoenbaum, Ph.D., senior advisor for mental health services, epidemiology and economics at NIMH. “What’s especially important is the finding that around 1.5 percent of boys aged 10-18 are on antipsychotics, and then this rate abruptly falls by half, as adolescents become young adults.” “Antipsychotics should be prescribed with care,” says Schoenbaum. “They can adversely affect both physical and neurological function and some of their adverse effects can persist even after the medication is stopped.”

Keyword: Development of the Brain; Drug Abuse
Link ID: 21121 - Posted: 07.02.2015

By Dina Fine Maron The game is a contemporary of the original Nintendo but it still appeals to today’s teens and lab monkeys alike—which is a boon for neuroscientists. It offers no lifelike graphics. Nor does it boast a screen. Primate players—whether human or not—are simply required to pull levers and replicate patterns of flashing lights. Monkeys get a banana-flavored treat as a reward for good performance whereas kids get nickels. But the game's creators are not really in it for fun. It was created by toxicologists at the U.S. Food and Drug Administration in the 1980s to study how chronic exposure to marijuana smoke affects the brain. Players with trouble responding quickly and correctly to the game’s commands may have problems with short-term memory, attention or other cognitive issues. The game has since been adapted to address a different question: whether anesthetics used to knock pediatric patients unconscious during surgery and diagnostic tests could affect a youngster's long-term neural development and cognition. Despite 20 years’ worth of experiments in young rodents and monkeys, there have been few definitive answers. To date, numerous studies suggest that being put under with anesthesia early in life seems somehow related to future cognitive problems. But whether this association is causal or merely coincidence is unclear. Researchers do know that the young human brain is exceptionally sensitive. When kids are exposed to certain harmful chemicals in their formative years, that experience can fundamentally alter the brain’s architecture by misdirecting the physical connections between neurons or causing cell deaths. But unraveling whether anesthetics may fuel such long-term damage in humans remains a challenge. © 2015 Scientific American

Keyword: Development of the Brain; Sleep
Link ID: 21116 - Posted: 07.01.2015

Hannah Devlin Science correspondent Two licensed drugs have been shown to halt brain degeneration in mice, raising the prospect of a rapid acceleration in the search for a medicine to beat Alzheimer’s disease. The results, presented on Tuesday at the Alzheimer’s Society annual research conference in Manchester, have been hailed as “hugely promising” because they involve medicines that are already known to be safe and well-tolerated in people – potentially cutting years from the timeline for drugs to reach patients. Speaking ahead of her presentation, Giovanna Mallucci, professor of clinical neuroscience at the University of Cambridge, said: “It’s really exciting. They’re licensed drugs. This means you’d do a straightforward basic clinical trial on a small group of patients because these are not new compounds, they’re known drugs.” The scientists have chosen not to name the two drugs, which are currently used for conditions unrelated to dementia, to avoid the possibility of patients seeking to use them ahead of any clinical trial to prove their efficacy. The findings build on a landmark study two years ago, showing that brain cell death could be halted in mice by switching off a faulty signal in the brain that stops new proteins being produced. However, the breakthrough relied on a compound that had severe physical side-effects including weight loss and diabetes, making it unsuitable for use in humans. The two drugs were identified after Mallucci’s team screened hundreds of licensed compounds in search for something safe that had the same protective effects on the brain. Clare Walton, research manager at the Alzheimer’s Society, said: “The new results are hugely promising because the drugs are already given to people and we know they’re safe.” © 2015 Guardian News and Media Limited

Keyword: Alzheimers
Link ID: 21114 - Posted: 07.01.2015

By Jan Hoffman Guinea pigs do not judge. They do not bully. They are characteristically amiable, social and oh-so-tactile. They tuck comfortably into child-size laps and err on the side of the seriously cute. When playing with guinea pigs at school, children with autism spectrum disorders are more eager to attend, display more interactive social behavior and become less anxious, according to a series of studies, the most recent of which was just published in Developmental Psychobiology. In previous studies, researchers in Australia captured these results by surveying parents and teachers or asking independent observers to analyze videotapes of the children playing. In the new report, however, the researchers analyzed physiological data pointing to the animals’ calming effect on the children. The children played with two guinea pigs in groups of three — one child who was on the spectrum and two typically developing peers. All 99 children in the study, ages 5 to 12, wore wrist bands that monitored their arousal levels, measuring electric charges that race through the skin. Arousal levels can suggest whether a subject is feeling anxious or excited. The first time that typically developing children played with the guinea pigs, they reported feeling happy and registered higher levels of arousal. The researchers speculate that the children were excited by the novelty of the animals. Children with autism spectrum disorders also reported feeling elated, but the wrist band measurements suggested their arousal levels had declined. The animals seem to have lowered the children’s stress, the researchers concluded. © 2015 The New York Times Company

Keyword: Autism
Link ID: 21111 - Posted: 06.30.2015

By Ariana Eunjung Cha One of the most heartbreaking things about Alzheimer's is that it has been impossible for doctors to predict who will get it before symptoms begin. And without early detection, researchers say, a treatment or cure may be impossible. Governments, drug companies and private foundations have poured huge amounts of money into trying to come up with novel ways to detect risk through cutting-edge technologies ranging from brain imaging, protein analysis of cerebrospinal fluid and DNA profiling. Now a new study, published in the journal Neurology, shows that perhaps something more old-fashioned could be the answer: a memory test. The researchers tracked 2,125 participants in four Chicago neighborhoods for 18 years, giving them tests of memory and thinking every three years. They found that those who scored lowest on the tests during the first year were 10 times more likely to be diagnosed with Alzheimer's down the road -- indicating that cognitive impairment may be affecting the brain "substantially earlier than previously established," the researchers wrote.

Keyword: Alzheimers; Learning & Memory
Link ID: 21109 - Posted: 06.30.2015

Amy Standen A doctor I interviewed for this story told me something that stuck with me. He said for every person with dementia he treats, he finds himself caring for two patients. That's how hard it can be to be a caregiver for someone with dementia. The doctor is Bruce Miller. He directs the Memory and Aging Center at the University of California, San Francisco. According to Miller, 50 percent of caregivers develop a major depressive illness because of the caregiving. "The caregiver is so overburdened that they don't know what to do next," he says. "This adds a huge burden to the medical system." This burden is going increase dramatically in the coming decade. By 2025, 7 million Americans will have Alzheimer's disease, according to one recent estimate. Millions more will suffer from other types of dementia. Together these diseases may become the most expensive segment of the so-called "silver tsunami" — 80 million baby boomers who are getting older and needing more medical care. The cost of caring for Alzheimer's patients alone is expected to triple by 2050, to more than $1 trillion a year. So UCSF, along with the University of Nebraska Medical Center, is beginning a $10 million study funded by the federal Centers for Medicare & Medicaid Innovation. Researchers plan to develop a dementia "ecosystem," which aims to reduce the cost of caring for the growing number of dementia patients and to ease the strain on caregivers. © 2015 NPR

Keyword: Alzheimers
Link ID: 21104 - Posted: 06.29.2015

Sharon Darwish Bottlenose dolphins have an average brain mass of 1.6 kg, slightly greater than that of humans, and about four times the size of chimpanzee brains. Although you couldn’t really imagine a dolphin writing poetry, dolphins demonstrate high levels of intelligence and social behaviour. For example, they display mirror self-recognition, as well as an understanding of symbol-based communication systems. Research into the differing brain sizes and intellectual capabilities within the animal kingdom is fascinating. Why have some species evolved to be more intelligent than others? Does brain size affect cognitive ability? Some studies say yes, but some insist otherwise. It really depends which species we are talking about. In humans, for example, larger brains do not indicate higher intelligence – otherwise Einstein, who had an average-sized brain, may have not been quite as successful in his career. (Yes, that link was to a 23-pager on the analysis of Einstein’s brain. It makes for great bedtime reading.) Most neuroscientists now believe that it is the structure of the brain on a cellular and molecular level that determines its computational capacity. Within certain animal species however, a larger brain offers evolutionary advantage. For example, large-brained female guppies are better survivors and demonstrate greater cognitive strengths than their smaller-brained counterparts. © 2015 Guardian News and Media Limited

Keyword: Development of the Brain; Genes & Behavior
Link ID: 21102 - Posted: 06.27.2015

By Nicholas Bakalar Exposure to air pollution may hasten brain aging, a new study has found. Researchers studied 1,403 women without dementia who were initially enrolled in a large health study from 1996 to 1998. They measured their brain volume with M.R.I. scans in 2005 and 2006, when the women were 71 to 89 years old. Using residential histories and air pollution data, they estimated their exposure to air pollution from 1999 to 2006. They used data recorded at monitoring sites on exposure to PM 2.5 — tiny particulate matter that easily penetrates the lungs. Each increase of 3.49 micrograms per cubic centimeter cumulative exposure to pollutants was associated with a 6.23 cubic centimeter decrease in white matter, the equivalent of one to two years of brain aging. The association remained after adjusting for many variables, including age, smoking, physical activity, blood pressure, body mass index, education and income. Previous studies have shown that air pollution can cause inflammation and damage to the vascular system, but this study, in The Annals of Neurology, showed damage to the brain itself. “This tells us that the damage air pollution can impart goes beyond the circulatory system,” said the lead author, Dr. Jiu-Chiuan Chen, an associate professor of preventive medicine at the Keck School of Medicine at the University of Southern California. “Particles in the ambient air are an environmental neurotoxin to the aging brain.” © 2015 The New York Times Company

Keyword: Neurotoxins; Development of the Brain
Link ID: 21082 - Posted: 06.23.2015

Children who have a good memory are better at telling lies, say child psychology researchers. They tested six and seven-year-olds who were given an opportunity to cheat in a trivia game and then lie about their actions. Children who were good liars performed better in tests of verbal memory - the number of words they could remember. This means they are good at juggling lots of information, even if they do tell the odd fib. Writing in the Journal of Experimental Child Psychology, researchers from the Universities of North Florida, Sheffield and Stirling, recruited 114 children from four British schools for their experiment. Using hidden cameras during a question-and-answer game, they were able to identify the children who peeked at the answer to a fictitious question, even though they were told not to. A potentially surprising finding (for parents) is that only a quarter of the children cheated by looking at the answer. Further questioning allowed the researchers to work out who was a good liar or a bad liar. They were particularly interested in children's ability to maintain a good cover story for their lie. In separate memory tests, the good liars showed they had a better working memory for words - but they didn't show any evidence of being better at remembering pictures (visuo-spatial memory). The researchers said this was because lying involves keeping track of lots of verbal information, whereas keeping track of images is less important. © 2015 BBC

Keyword: Learning & Memory; Development of the Brain
Link ID: 21079 - Posted: 06.22.2015

Maanvi Singh Teenagers aren't exactly known for their responsible decision making. But some young people are especially prone to making rash, risky decisions about sex, drugs and alcohol. Individual differences in the brain's working memory — which allows people to draw on and use information to make decisions — could help explain why some adolescents are especially impulsive when it comes to sex, according to a study published Wednesday in Child Development. "Working memory is the ability to keep different things in mind when you're making decisions or problem solving," explains Atika Khurana, an assistant professor of counseling psychology at the University of Oregon who led the study. Khurana and her colleagues rounded up 360 adolescents, ages 12 to 15, and assessed their working memory using a series of tests. For example, the researchers told the participants a string of random numbers and asked them to repeat what they heard in reverse order. "We basically tested their ability to keep information in mind while making decisions," Khurana says. The researchers then tracked all the participants for two years, and asked about the teens' sexual activity. And through another series of tests and surveys, the researcher tried to gauge how likely each teen was to act without thinking, to make rash decisions and take risks. There was a correlation between weaker working memory and the likelihood that a teen would have sex — including unprotected sex — at a younger age. And they were more likely to act without much deliberation. That trend held true even after the researchers accounted for the teenagers' age, socioeconomic status and gender. © 2015 NPR

Keyword: Development of the Brain; Learning & Memory
Link ID: 21070 - Posted: 06.18.2015

By Nicholas Bakalar A new study has found a simple way to significantly reduce teenage smoking: raise the tobacco sales age to 21. In 2005, Needham, Mass., did just that, while surrounding communities kept their age limit at 18. Researchers surveyed 16,000 high school students in Needham and 16 surrounding communities four times between 2006 and 2012, gathering data on their smoking habits. The study is in Tobacco Control. Over the seven years, the number of children under 18 buying cigarettes in Needham decreased to 11.6 percent from 18.4 percent, while in the surrounding communities it hardly changed — down to 19 percent from 19.4. In 2006, 12.9 percent of students in Needham and 14.8 percent of students in surrounding communities reported having smoked in the past 30 days. By 2010, 6.7 percent of Needham students reported smoking, compared with 12 percent in other towns. At the end of the study in 2012, smoking had declined to 5.5 percent in Needham and 8.5 percent outside. “More than 80 percent of smokers begin before 18,” said the lead author, Shari Kessel Schneider, project director at the Education Development Center in Waltham, Mass. “Our findings provide strong support for initiatives going on all across the country to increase the sales age as a means for decreasing youth access to cigarettes, initiation of smoking, and ultimately addiction.” © 2015 The New York Times Company

Keyword: Drug Abuse; Development of the Brain
Link ID: 21069 - Posted: 06.18.2015

By James Gallagher Health editor, BBC News website Scientists have discovered a chemical in blood that indicates whether people will have declining brain function. Looking for the earliest signs of Alzheimer's disease, they analysed levels of 1,129 proteins circulating in the blood of more than 200 twins. These were compared with data from cognitive-function tests over the next decade, in Translational Psychiatry. And levels of one protein, MAPKAPK5, tended to be lower in those people whose brains declined. MAPKAPK5 is involved in relaying chemical messages within the body, although its connection with cognitive decline is unclear. Dementia cases are expected to treble globally by 2050, but there is no cure or treatment. It can take more than a decade from the first changes in the brain to culminate in symptoms such as memory loss, confusion and personality change. And drug companies believe they need to treat patients years before symptoms appear in order to protect the brain. Dr Steven Kiddle, a Medical Research Council scientist at King's College London, told the BBC News website: "People think it may be hard to reverse 20 years of potential damage to your brain. "But if you could start much earlier in that process, then you might be able to find something that works." He said a blood test could help identify people for clinical trials. But he added: "A test you could go in to your doctor to say, 'Do I have Alzheimer's disease or not?' I think that's a long way off." © 2015 BBC

Keyword: Alzheimers
Link ID: 21064 - Posted: 06.17.2015

by Meghan Rosen When we brought Baby S home from the hospital six months ago, his big sister, B, was instantly smitten. She leaned her curly head over his car seat, tickled his toes and cooed like a pro — in a voice squeakier than Mickey Mouse’s. B’s voice — already a happy toddler squeal — sounded as if she'd sucked in some helium. My husband and I wondered about her higher pitch. Are humans hardwired to chitchat squeakily to babies, or did B pick up vocal cues from us? (I don’t sound like that, do I?) If I’m like other mothers, I probably do. American English-speaking moms dial up their pitch drastically when talking to their children. But dads’ voices tend to stay steady, researchers reported May 19 in Pittsburgh at the 169th Meeting of the Acoustical Society of America. “Dads talk to kids like they talk to adults,” says study coauthor Mark VanDam, a speech scientist at Washington State University. But that doesn’t mean fathers are doing anything wrong, he says. Rather, they may be doing something right: offering their kids a kind of conversational bridge to the outside world. Scientists have studied infant- or child-directed speech (often called “motherese” or “parentese”) for decades. In American English, this type of babytalk typically uses high pitch, short utterances, repetition, loud volume and slowed-down speech. Mothers who speak German Japanese, French, and other languages also tweak their pitch and pace when talking to children. But no one had really studied dads, VanDam says. © Society for Science & the Public 2000 - 2015.

Keyword: Language; Development of the Brain
Link ID: 21050 - Posted: 06.15.2015

By Jessica Schmerler Approximately one in 68 children is identified with some form of autism, from extremely mild to severe, according to the U.S. Centers for Disease Control. On average, diagnosis does not occur until after age four, yet all evidence indicates that early intervention is the best way to maximize the treatment impact. Various tests that look for signs of autism in infants have not been conclusive but a new exercise could improve early diagnosis, and also help reduce worry among parents that they did not intervene as soon as possible. The two most widely used tests to measure symptoms, the Autism Observation Scale for Infants (AOSI) and the Autism Diagnostic Observation Schedule (ADOS), cannot be used before the ages of 12 or 16 months respectively. The AOSI measures precursors to symptoms, such as a baby’s response to name, eye contact, social reciprocity, and imitation. The ADOS measures the characteristics and severity of autism symptoms such as social affectation and repetitive and restrictive behaviors. Now a group of scientists at the Babylab at Birkbeck, University of London think they have identified a marker that can predict symptom development more accurately and at an earlier age: enhanced visual attention. Experts have long recognized that certain individuals with autism have superior visual skills, such as increased visual memory or artistic talent. Perhaps the most well known example is Temple Grandin, a high-functioning woman with autism who wrote, “I used to become very frustrated when a verbal thinker could not understand something I was trying to express because he or she couldn’t see the picture that was crystal clear to me.” © 2015 Scientific American

Keyword: Autism; Attention
Link ID: 21045 - Posted: 06.13.2015

Owning a cat as a kid could put you at risk for schizophrenia and bipolar disorder later on because of parasites found in feline feces, new research says. Previous studies have linked the parasite toxoplasma gondii (T. gondii) to the development of mental disorders, and two more research papers published recently provide further evidence. Researchers from the Academic Medical Centre in Amsterdam looked at more than 50 studies and found that a person infected with the parasite is nearly twice as likely to develop schizophrenia. The other study, led by Dr. Robert H. Yolken of Johns Hopkins University School of Medicine in Baltimore, confirmed the results of a 1982 questionnaire that found half of people who had a cat as a kid were diagnosed with mental illnesses later in life compared to 42% of those who didn't grow up with a cat. "Cat ownership in childhood has now been reported in three studies to be significantly more common in families in which the child is later diagnosed with schizophrenia or another serious mental illness," the authors said in a press release. The findings were published in Schizophrenia Research and Acta Psychiatrica Scandinavica. T. gondii, which causes the disease toxoplasma, is especially risky for pregnant women and people with weak immune symptoms. The parasite can also be found in undercooked meat and unwashed fruits and vegetables.

Keyword: Schizophrenia; Neurotoxins
Link ID: 21038 - Posted: 06.10.2015

By Sue Bailey, The Canadian Press Scientific studies increasingly suggest marijuana may not be the risk-free high that teens — and sometimes their parents — think it is, researchers say. Yet pot is still widely perceived by young smokers as relatively harmless, said Dr. Romina Mizrahi, director of the Focus on Youth Psychosis Prevention clinic and research program at the Centre for Addiction and Mental Health. She cites a growing body of research that warns of significantly higher incidence of hallucinations, paranoia and the triggering of psychotic illness in adolescent users who are most predisposed. "When you look at the studies in general, you can safely say that in those that are vulnerable, it doubles the risk." Such fallout is increasingly evident in the 19-bed crisis monitoring unit at the Children's Hospital of Eastern Ontario in Ottawa. "I see more and more cases of substance-induced psychosis," said Dr. Sinthu Suntharalingam, a child and adolescent psychiatrist. "The most common substance that's abused is cannabis." One or two cases a week are now arriving on average. "They will present with active hallucinations," Suntharalingam said. "Parents will be very scared. They don't know what's going on. "They'll be seeing things, hearing things, sometimes they will try to self-harm or go after other people." Potential effects need to be better understood She and Mizrahi, an associate professor in psychiatry at University of Toronto, are among other front-line professionals who say more must be done to help kids understand potential effects. "They know the hard drugs, what they can do," Suntharalingam said. "Acid, they'll tell us it can cause all these things so they stay away from it. But marijuana? They'll be: 'Oh, everybody does it."' Mizrahi said the message isn't getting through. ©2015 CBC/Radio-Canada.

Keyword: Drug Abuse; Development of the Brain
Link ID: 21025 - Posted: 06.08.2015

by Helen Thomson For the first time, scientists have discovered a mechanism in humans that could explain how your lifestyle choices may impact your children and grandchildren's genes. Mounting evidence suggests that environmental factors such as smoking, diet and stress, can leave their mark on the genes of your children and grandchildren. For example, girls born to Dutch women who were pregnant during a long famine at the end of the second world war had twice the usual risk of developing schizophrenia. Likewise, male mice that experience early life stress give rise to two generations of offspring that have increased depression and anxiety, despite being raised in a caring environment. This has puzzled many geneticists, as genetic information contained in sperm and eggs is not supposed to be affected by the environment, a principle called the August Weismann barrier. But we also know the activity of our own genes can be changed by our environment, through epigenetic mechanisms . These normally work by turning a gene on or off by adding or subtracting a methyl group to or from its DNA. These methyl groups can inactivate genes by making their DNA curl up, so that enzymes can no longer access the gene and read its instructions. Such epigenetic mechanisms are high on the list of suspects when it comes to explaining how environmental factors that affect parents can later influence their children, such as in the Dutch second world war study, but just how these epigenetic changes might be passed on to future generations is a mystery. © Copyright Reed Business Information Ltd.

Keyword: Epigenetics; Schizophrenia
Link ID: 21022 - Posted: 06.06.2015