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News- Page 3
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Research : Home Videos Suggest Regression Occurs in Some Autistic Children
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Posted by sylvia on Friday, September 30, 2005 (10:08:47)
NewsWise August 2005
Home videos of first and second year birthday parties provide support for parents’ reports of children whose behavior seemed normal when they were one-year-olds but then display symptoms of autism at the age of two years, according to a study in the August issue of Archives of General Psychiatry, one of the JAMA/Archives journals.
Although symptoms of autism have been observed in children as young as eight to 12 months, some parents report that their child had normal or near-normal development and then experienced a regression, as their communication and/or social skills worsened, according to background information in the article. Estimates of the prevalence of this “regressive pattern†vary widely and depend for the most part on parental memories that may be biased by later events, the authors suggest.
Emily Werner, Ph.D., and Geraldine Dawson, Ph.D., of the University of Washington, Seattle, analyzed home videotapes of first and second year birthday parties for children without autism and for children who have been diagnosed with autism spectrum disorder (ASD). Of the 56 children included in the study, 15 were children diagnosed with ASD whose parents reported a worsening in social and/or communication skills during the second year of life, 21 were children with ASD whose parents reported that they had had impairments before age one year (early onset) and 20 were typically developing children. All the children in the study were younger than seven and all but three were younger than four years old.
The researchers coded the frequency and duration of a number of behaviors seen on the videotape, including language, gaze, repetitive behavior, emotion and playing with toys. In addition, they conducted an interview with the child’s primary caregiver designed to help the caregiver recall the child’s early development, including questions about social responsiveness, language skills and temperamental differences.
Infants with ASD with regression showed more frequent use of words and babble at 12 months compared to normal infants. Early onset ASD infants showed the least frequent use of words and babble. The level of joint attention (frequency of pointing) was the same for normal infants and infants with ASD with regression at 12 months. “In contrast, infants with ASD with early onset of symptoms and no regression displayed fewer joint attention and communicative behaviors at 12 months of age,†the authors report. “By 24 months of age, both groups of toddlers with ASD displayed fewer instances of word use, vocalizations, declarative pointing, social gaze, and orienting to name [responding to the use of their name] as compared with typically developing 24-month-olds.â€
“While we cannot be certain from these data that children with autistic regression were developing entirely normally before the regression occurred, the results of the present study suggest that at least some children with autism do not display prototypical impairments in joint attention, such as a lack of declarative pointing, nor do they display obvious delays in their use of language at the end of the first year of life,†the authors write. “Future research should focus on examining whether autistic regression in the first two years of life is distinct from later regression seen in cases of childhood disintegrative disorder and determining whether regressive forms of autism represent genetic subtypes and/or distinct etiologies [causes].â€
This study was supported by grants from the National Institutes of Child Health and Human Development (NICHD), Rockville, Md., which is part of the NICHD Collaborative Program of Excellence in Autism, and was facilitated by a NICHD grant to the Center on Human Development and Disability, Seattle.
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Research : Rodent social behavior encoded in junk DNA
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Posted by sylvia on Saturday, August 06, 2005 (09:52:55)
EurekAlert 09/06/05
By Jules Asher
A discovery that may someday help to explain human social behavior and disorders such as autism has been made in a species of pudgy rodents by researchers funded, in part, by the National Institutes of Health's (NIH) National Institute of Mental Health (NIMH) and National Center for Research Resources (NCRR).
The researchers traced social behavior traits, such as monogamy, to seeming glitches in DNA that determines when and where a gene turns on. The length of these repeating sequences – once dismissed as mere junk DNA – in the gene that codes for a key hormone receptor determined male-female relations and parenting behaviors in a species of voles. Drs. Larry Young and Elizabeth Hammock, Emory University, report on their findings in the mouse-like animals native to the American Midwest in the June 10, 2005 Science.
The discovery is the latest in a two decades-old scientific quest for the neural basis of familial behavior begun at the NIMH Intramural Research Program in the mid l980s by now NIMH director Thomas Insel, M.D. By l993, his team had discovered that the distribution of brain receptors that bind to the hormone vasopressin differed dramatically between monogamous and polygamous vole species and accounted for their divergent lifestyles. Yet, how such behavioral differences could have evolved in animals that otherwise appear almost identical remained a mystery.
"This research appears to have found one of those hotspots in the genome where small differences can have large functional impact," explained Insel. "The Emory researchers found individual differences not in a protein-coding region, but in an area that determines a gene's expression in the brain. This is an extraordinary example of research linking gene variation to brain receptors to behavior."
Hammock and Young were particularly intrigued with microsatellites, repeating sequences of letters in the genetic code peppered throughout these regulatory areas of the vasopressin receptor gene.
"It was considered junk DNA because it didn't seem to have any function," noted Hammock.
Each animal species has its own signature microsatellites; for example, the repeating letter sequences are much longer in monogamous than in polygamous vole species. But even within a species, there are differences in the number of letters in the sequence among individuals.
The researchers first showed in cell cultures that the vole vasopressin receptor microsatellites could modify gene expression. Next, they bred two strains of a monogamous species, the prairie vole – one with a long version of the microsatellites and the other with a short version.
Adult male offspring with the long version had more vasopressin receptors in brain areas involved in social behavior and parenting (olfactory bulb and lateral septum). They also checked out female odors and greeted strangers more readily and were more apt to form pair bonds and nurture their young.
"If you think of brain circuits as locked rooms, the vasopressin receptor as a lock on the door, and vasopressin as the key that fits it, only those circuits that have the receptors can be 'opened' or influenced by the hormone," added Hammock. "An animal's response to vasopressin thus depends upon which rooms have the locks and our research shows that the distribution of the receptors is determined by the length of the microsatellites."
Prairie voles with the long version have more receptors in circuits for social recognition, so release of vasopressin during social encounters facilitates social behavior. If such familial traits are adaptive in a given environment, they are passed along to future generations through natural selection.
Variability in vasopressin receptor microsatellite length could help account for differences in normal human personality traits, such as shyness, and perhaps influence disorders of sociability like autism and social anxiety disorders, suggest the researchers. The Emory researchers have found that the bonobo, an ape noted for its empathic traits, unlike its relative the chimpanzee, has a microsatellite with a sequence similar to that of humans. Two studies have found modest associations between alterations in this microsatellite and autism in some families. As subgroups of autism spectrum disorders are characterized, a stronger connection may emerge.
Far from being junk, the repetitive DNA sequences, which are highly prone to mutate rapidly, may ultimately exert their influence through complex interactions with other genes to produce individual differences and social diversity, according to Young.
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Research : Autism and X-fragile syndrome
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Posted by sylvia on Saturday, August 06, 2005 (09:45:15)
Innovations-report.de 09/06/05
By Elhuyar Fundazioa
According to the World Health organisation, the definition of autism is based on a specific pattern of behaviour characteristics, as neither its aetiology nor pathology is defined. This is why a search for autism markers is proposed at three levels: morphological, cytogenetic and molecular.
In the 80s, a research group at the Leioa campus of the University of the Basque Country worked on dermatoglyphs, an analysis technique applied to autistic children. Dermatoglyphs, or handprints and footprints, are useful in the morphological analysis of the symmetry of the human body.
That initial study of dermatoglyphs enabled the fluctuating asymmetry between the sides of the body to be seen, i.e. that asymmetry with a non-definable pattern being the more common amongst autistic children than in the rest of the population.
Fragile sites
Following on from this initial morphological study, the research took a cytogenetic turn. In this second phase, chromosomes of autistic children were analysed. This was undertaken with the knowledge that certain sites on the chromosomes were more prone to breaking than others. One of these fragile locations is found on the X chromosome and is known as FRAXA.
The results show that children with autism had a significantly greater frequency of expression of these fragile sites than the control population. The FRAXA fragile site expressed itself only amongst autistic children, although not in all. Thus, at a cytogenetic level, FRAXA s the most important marker for a genetic alteration that underlies autism.
Too many repetitions
Effectively, the genetic alteration on this location of the X chromosome was identified at the beginning of the 1990s. The gene known as FMR1 (Female Mental Retardation 1) is responsible for the X-fragile syndrome related to autism.
But not all autistic children showed this genetic alteration and, so, an analysis at a molecular level was undertaken in order to determine the prevalence of the X-fragile syndrome amongst individuals with mental backwardness in the Basque Country.
From a simple blood DNA analysis, it is known that the FMR1 gene has a CGG (cytosine- guanine-guanine) tri-nucleotide, usually repeated between 6 and 54 times in normal persons. On the other hand, amongst premutated persons, these repetitions appear between 55 and 200 times and, in those who have the mutated gene - i.e. those suffering from the X fragile syndrome -, they appear more than 200 times, reaching 1,000 repetitions in some cases.
The results of this analysis show that none of the individuals with the X-fragile mutation was of Basque origin though they had mental backwardness or autistic characteristics. These results led to the investigation of the stability of the FMR1 gene amongst the Basque population. The project was subsequently widened to undertake separate analyses of the different Basque regions. This study showed that there exist different mutational paths of the FMR1 gene amongst the Basque population and which may be of a relatively recent origin – thus explaining the absence of the X fragile syndrome amongst this population.
With this conclusion reached, the studies now target persons with the permutated form of the gene given that three pathologies associated with this CGG premutation have been discovered: moderate mental backwardness and autistic characteristics, premature ovarian failure before the age of 45 and ataxia – a pathology with trembling similar to that of Parkinson’s. In short, there is still much to investigate regarding the X fragile syndrome.
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Research : Autism's cause unknown, but research points to genetics
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Posted by sylvia on Saturday, June 04, 2005 (14:19:16)
Pittsburgh Live 01/05/05
By Liz Hayes
Autism is more common than most serious developmental disabilities, but its cause probably is the least understood.
Scientists know that an extra chromosome causes Down syndrome, which the Centers for Disease Control and Prevention estimate affects about half as many children as autism spectrum disorders. Cerebral palsy, also less common than autism, can be caused by head injuries, jaundice, infections or lack of oxygen.
The most frequent serious developmental disability is mental retardation, which is about three times as common as autism. Although not all the causes of mental retardation are known, several have been identified, including fetal alcohol syndrome and a variety of genetic conditions.
But autism's origins are largely a mystery.
The medical community has come a long way from the mid-20th century suppositions of Dr. Bruno Bettelheim, a developmental psychologist who theorized autism was the result of cold and unloving mothers who weren't stimulating their children.
Bettelheim's "refrigerator mother" theory was debunked decades ago when scientists determined autism was a biological, not psychological, condition.
Now they are trying to determine whether the biology has a basis in genetics or the environment -- or both.
A possible genetic connection was first considered in the late 1970s when a study noted twins of autistic children had a greater than average chance of also being autistic. Even siblings, though at a low risk, are slightly more likely than the general population to be diagnosed with autism.
Also, autism is about four times more common in boys than girls. The unexplained tendency suggests a genetic component.
Researchers have found evidence that may link several chromosomal abnormalities to autism. The disorder sometimes occurs along with identified genetic conditions, such as fragile x syndrome, untreated phenylketonuria (PKU), neurofibromatosis and tuberous sclerosis.
However, all of these genetic conditions combined only account for a small percentage of autism cases and no single gene or combination of genes has been identified as a cause.
And if genes alone cause autism, scientists would be hard-pressed to explain the exploding number of autism cases.
Many therefore point to some environmental catalyst that either exacerbates a genetic condition or works independently to cause autism. The popular theory now is that people can be born with a genetic predisposition that, coupled with some environmental trigger, causes autism.
"We know there have to be some environmental impacts," said Dr. Laura Hewitson, a University of Pittsburgh Medical School professor and autism researcher with the Magee-Women's Research Institute.
Environmental toxins and vaccinations have long been fingered as possible triggers.
Autism and vaccines
Childhood vaccinations especially have been scrutinized because some children don't exhibit many autistic characteristics until they are several years old -- after they are exposed to a series of immunizations. On the other hand, it is at this time when language and learning problems that can prompt an autism diagnosis become more apparent.
The measles, mumps and rubella (MMR) vaccine in particular is singled out due to some controversial studies that link intestinal problems and autism with the measles virus. Others have theorized the combined MMR vaccine might overburden and weaken the immune system and have called for the measles, mumps and rubella vaccines to be administered as separate immunizations.
The Centers for Disease Control and Prevention, the Institute of Medicine and the American Academy of Pediatrics all contend these studies do not prove the MMR vaccine causes autism and maintain the combined shot is safer because the delay between individual shots would expose children needlessly to the remaining viruses.
The other reason vaccinations are considered a possible cause is due to a mercury-based preservative called thimerosal that was used in multidose vials to prevent contamination. Thimerosal never was used in the MMR vaccine, but it was common in children's doses of diphtheria, tetanus and pertussis (DTaP), hepatitis B (HepB) and Haemophilus influenzae type b (Hib).
Thimerosal, which is about 50 percent mercury, was introduced in the 1930s as an effective bacteria and fungus killer in vaccines. Shortly after its introduction, autism was identified, which prompted some to wonder whether there is a correlation between the two, especially because some symptoms of autism are similar to those seen in mercury poisoning.
Although mercury exposure is associated with a variety of serious health problems, including brain, nerve and kidney damage and possibly cancer, thimerosal was thought to be harmless because vaccines contained only a minuscule amount of it.
However, as more childhood immunizations containing thimerosal were required, the Food and Drug Administration determined it was possible for some infants to be exposed to cumulative amounts of mercury that cross into unsafe consumption levels as set by the Environmental Protection Agency. As a precaution, several federal agencies began to work with pharmaceutical companies to reduce or eliminate the amount of thimerosal in vaccines.
Today, all childhood vaccines contain only a trace (one microgram or less) of mercury per dose or no thimerosal at all. Thimerosal-free vaccines include most brands of DTaP, MMR, HepB, Hib, inactivated poliovirus, varicella (chicken pox), pneumococcal and meningococcal, according to the Food and Drug Administration.
Most flu vaccines still contain thimerosal, although some doses are produced with only a trace of the preservative.
Aside from thimerosal, children also can be exposed to mercury through industrial emissions and fish consumption.
Dr. Scott Faber, a specialist in neurodevelopmental disabilities and behavioral pediatrics at the Children's Institute in Pittsburgh, said there is emerging evidence that heavy metal build-up in the body can cause the neurological impairment seen in autism.
Faber and Hewitson, the researcher with Magee's Pittsburgh Development Center, each said there may be a connection between mercury exposure in the womb and autism.
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Research : Specific behaviors seen in infants can predict autism
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Posted by sylvia on Saturday, June 04, 2005 (11:36:04)
Medical News Today 29/04/05
Canadian researchers have become the first to pinpoint specific behavioral signs in infants as young as 12 months that can predict, with remarkable accuracy, whether a child will develop autism.
The preliminary findings, published this month in the International Journal of Developmental Neuroscience, were taken from an ongoing study of 200 Canadian infants, the largest study of its kind in the world. The infants, many of whom have been followed from birth to 24 months, are younger siblings of children who have been diagnosed with autism.
Studies show that families with one autistic child have a roughly five to10 percent chance of a second child being diagnosed with autism, a rate of recurrence about 50 times higher than the general population.
The Canadian study, which began as a collaboration of McMaster University's Offord Centre for Child Studies in Hamilton, The Hospital for Sick Children in Toronto and the IWK Health Centre in Halifax, has gained international attention. Initially funded by The Hospital for Sick Children Foundation, and currently by the Canadian Institutes of Health Research (CIHR), it has mushroomed into a global initiative involving leading autism researchers in 14 cities across Canada and the U.S.
Chaired by Lonnie Zwaigenbaum, a developmental pediatrician with the Offord Centre and McMaster Children's Hospital and a lead investigator for the Canadian study, the Canada - U.S. Baby Sibs Research Consortium is supported by the National Alliance for Autism Research (NAAR) and the National Institute of Child Health and Human Development (NICHD) in the U.S. It is widely regarded as one the most exciting developments in autism research today.
“This is groundbreaking work that is pushing the frontier of what we know about the biological nature of autism, and why it emerges so early in life,†says Dr. Zwaigenbaum. “Our hope is that it will lead to the development of new and earlier treatments that could make a huge difference for these children.â€
Second only to mental retardation as the most common developmental disability, autism forms part of a spectrum of related disorders referred to as the autism spectrum disorders (ASDs). Although symptoms can range from mild to severe, those affected typically exhibit severe impairments in social interaction and communication, and engage in repetitive, solitary activities.
The complex nature of the disorder makes it difficult to diagnose. In the absence of any biological marker, clinicians have been typically forced to rely on parental reports, home videos and direct observations of behavior, using standardized tools like the Checklist for Autism in Toddlers (CHAT). But these tools were designed for children 18 months and older; there has been no instrument to measure autistic behaviors in young infants.
So the Canadian researchers designed their own. Led by Susan Bryson, Craig Chair in Autism Research at the IWK Health Centre/Dalhousie University, and co-lead investigator for the study, they developed the Autism Observation Scale for Infants (AOSI). The scale maps the development of infants as young as six months against 16 specific risk markers for autism, including such behaviors such as not smiling in response to the smiles of others or not responding when one's name is called.
“The predictive power of these markers is remarkableâ€, says Dr. Zwaigenbaum. “We are finding that within this high-risk group of siblings, almost all of the children who are diagnosed with autism by age two years have seven or more of these markers by the time they are a year old.â€
The researchers found that even at six months of age there were certain behaviors that distinguished those siblings later diagnosed with autism from other siblings. These included a passive temperament and decreased activity level at age six months, followed by extreme irritability, a tendency to fixate on objects, reduced social interaction and lack of facial expression as they approached the age of 12 months. At one year, these same children also showed difficulties with language and communication - they used fewer gestures, understood fewer phrases and had lower scores for both expressive and receptive language.
It is not known whether these risk markers constitute an early manifestation of the disorder, or are behaviors that reduce the child's opportunities to learn from social experiences, thereby contributing to a pattern of development that may lead to autism. Still, the results shed new light on when autism starts and how early it can be detected.
“This is an important breakthrough in our understanding of the initial behavioral signs of autism,†says Peter Szatmari, Director of the Offord Centre and a member of the Canadian research team. “By identifying these signs in children as soon as they are detectable, clinicians will be able to diagnose earlier, interventions can begin earlier, and we can improve the long-term outcomes for these children.â€
Jessica Brian, who with Wendy Roberts is one of two investigators at The Hospital for Sick Children working on the study, has already developed and begun to evaluate innovative interventions for infants showing early signs.
John Kelton, dean and vice-president of McMaster's Faculty of Health Sciences, said: “This is an important step forward. The team at the Offord Centre is making a real difference towards better care for children and families affected by autism.â€
The Offord Centre for Child Studies at McMaster University is an internationally recognized centre of research focused on early child development. The Centre is affiliated with the McMaster Children's Hospital, Hamilton Health Sciences. For more information, go to http://www.offordcentre.com.
Contact: Veronica McGuire
vmcguir@mcmaster.ca
90-552-591-402-2169
McMaster University
http://www.mcmaster.ca
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