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AUTISM FIRST STEPS
AUTISM DAILY NEWSLETTER
Sunday January 6, 2002
INDEX:
* Critical
Period For Acquiring Non-Verbal Language
* Medical Research Council review sets research agenda for autism
* Study finds there's a critical time for learning all languages,
including
sign language
* District evaluates full inclusion
******************************
Critical Period For Acquiring Non-Verbal Language
Neuroscientists
examining the brain activity of people who learned to speak American Sign
Language (ASL) at different times in their lives have found the first evidence
that there is a critical period for acquiring a non-verbal language, just as
there is for spoken languages.Using functional magnetic resonance imaging
(fMRI), the researchers discovered patterns of brain activity in bilingual
people who learned ASL before puberty differed from those who learned it after
puberty.The findings are reported in this month's issue of the journal Nature
Neuroscience. They indicate there are regions in the brain's right
hemisphere that are activated when children who learned ASL before puberty are
reading sign language. The brains of children who learned ASL after puberty
show significantly less right hemisphere activity when they are doing the same
activity.There is widespread acceptance among neuroscientists that there is a critical
period for first language acquisition, and that children who are not exposed to
any language before puberty, or perhaps sooner, are unable to fully acquire and
use the principles of language. There also is evidence of similar critical
periods for acquiring a second language."We know that late learners of
ASL, while they are very fluent, never will be fully fluent like native, or
early, learners of ASL," said David Corina, a University of Washington
associate professor of psychology and a co-author of the study. Corina is
fluent in ASL."One aspect of ASL that is difficult for late learners is
verb signs of motion. You see some subtle errors in their use of these verbs,
just as you might detect subtle grammatical differences when listening to bilingual
users of a spoken language when they are not using their native
tongue."Other members of the research team are Aaron Newman, a University
of Oregon doctoral student; Helen Neville, University of Oregon psychology
professor; Daphne Bavelier, assistant professor of brain and cognitive sciences
at the University of Rochester, and Peter Jezzard, a physicist at John
Radcliffe Hospital in England.The new study builds on earlier work by this
research team showing that right hemisphere activity, along with activation in
the left hemisphere, is necessary for processing ASL. The left hemisphere
activity has long been associated with the processing of spoken
languages."One area of the brain that is the signature, or specific, to
signers if they learned ASL as a native signer, is the right angular
gyrus," Corina said.It is located at the juncture of the temporal and
parietal lobes. Activation of the left angular gyrus has been associated with
reading English and other spoken languages for many years. The new study shows
consistent activation of the right angular gyrus among native signers and some,
but not consistent, activation of that brain region among late signers.The
study involved 27 bilingual subjects. Sixteen were hearing persons born to deaf
parents. They learned ASL and English from birth as native languages. The
remaining 11 were the late learners who had English as their native language
and learned ASL after puberty, in early adulthood. All of the subjects watched
a screen while their brains were imaged using fMRI and were asked to read
written English sentences and meaningless strings of consonants. They also were
shown and asked to read ASL sentences and meaningless gestures that were
similar to real ASL signs."This work is important because we want to
understand the neural systems underlying language," said Corina. "We
want to know if they are malleable or fixed and the degree to which they may
vary in different languages. We now know there is activation in the right
hemisphere when native signers view ASL, and to see that this is dependent on
early exposure suggests there are specific times when neural systems for
language may be particularly sensitive to change."He added that the
research has implications for early education of all children because it stressed
the need for early language exposure at critical times in development. And now,
it is equally important in education for the deaf to ensure linguistic
competency in ASL.The National Institute of Deafness and Communicative
Disorders, the National Sciences and Engineering Council of Canada, the Charles
A. Dana Foundation and a University of Oregon postgraduate scholarship funded
the research. - By Joel Schwarz
[Contact: David Corina, Helen Neville, Joel Schwarz]
http://unisci.com/stories/20021/0104026.htm
******************************
Medical Research Council review sets research
agenda for autism
Susan Mayor, London The
Medical Research Council has published a major review of research which reveals
that the prevalence of autism is higher than had been thought but indicates no
association with the measles, mumps, and rubella vaccination.The review was
commissioned by the Department of Health in March 2001, partly in response to
public concerns raised by research alleging that MMR vaccination might be
linked to an apparent increase in the numbers of children with autism. It was
designed to be a wide ranging review of research into different aspects of
autism and other disorders in the autism spectrum, to identify gaps in
knowledge and to make recommendations on future research in the United Kingdom.
Three groups of scientists examined the research evidence and assessed the
strength of knowledge based on research in epidemiology and case definition;
physiology and infection; and psychology and behaviour. For the first time in a
research review by the council there was extensive input from the outset from
lay people, who put forward questions that reflected the concerns of parents of
children with autism. The report found that autism was more prevalent than had
previously been thought: around six in 1000 young children have a disorder in
the autism spectrum. Carol Dezateux, clinical reader in epidemiology at the
Institute of Child Health at Great Ormond Street NHS Trust and chairwoman of
the review’s epidemiology subgroup, said: "This estimate makes autism
spectrum disorders far more common than was previously generally
recognised."Most of the apparent increase was considered by the reviewers
to have resulted from changes in case definition, as well as increased
awareness of the condition. The reviewers thought it most likely that autism
results from several causes, but they argued that the strongest evidence was
for a genetic component. They said: "It seems likely that several genes
interact to create susceptibility to the disorder. The interplay between
genetic and environmental factors is also likely to play a key role but the
nature of these interactions is not yet known." It was concluded that
current evidence did not support the link between MMR and autism spectrum
disorders. The review was chaired by Professor Eve Johnstone, who is also
chairwoman of the council’s neurosciences and mental health research board. She
said, "The report has identified some successes in research into autism
but there is still a long way to go to better understand these disorders."
She added: "The participation in this review of people with autism, their
carers, and people with experience of support groups has enriched both the
process and its outputs. Further partnerships which give lay organisations
access to scientific expertise and give scientists access to lay perspectives
can only be of benefit." For the future, the report recommends building on
the existing strengths of research into autism by improving coordination
between different research disciplines and improving research training in
service settings. It also called for more research on the definition of autism
spectrum disorders, especially in adults, noting that such research is
"crucial both for future research and for provision of services" for
people with the disorder. More basic biological research studies were also
suggested—an acknowledgement that there is still a lot of uncertainty about the
biological processes involved in autism, in the brain as well as other organs.
Large population studies were proposed, to address questions about
environmental risks and their interaction with genetic factors. The council is
now discussing with the Department of Health how to act on these proposals.Dr
Dezateux concluded that progress in autism research would depend on adequate
funding.The Medical Research Council’s review of autism research is available
on its website: www.mrc.ac.uk
http://bmj.com/cgi/content/full/324/7328/10/b
******************************
Screening for inherited metabolic disease in newborn infants using tandem mass
spectrometry
Further assessment of performance and
outcome is needed
Although individually rare, inborn
errors of metabolism represent a potentially preventable cause of death and
disability. Screening for
phenylketonuria (birth prevalence 10 per 100 000) was introduced in the United
Kingdom over 30 years ago. It has proved successful in preventing severe mental
retardation. The development of tandem mass spectrometry enables a wide variety of additional compounds to be assayed on the dried blood spots routinely collected from newborn infants.1 The combined birth prevalence of disorders, excluding
phenylketonuria, which could be detected by screening is about 20 per 100 000.
Of these, medium chain acyl CoA dehydrogenase deficiency is one of the most
important. However, despite experience of screening over a million infants,
many questions about screening for this disorder remain unanswered. In the
United Kingdom between 5 and 11 per 100 000 live born infants have medium chain
acyl CoA dehydrogenase deficiency, which is about 35 to 70 children each year.2 This recessively inherited disorder classically presents during
infancy and early childhood with a severe illness characterised by
encephalopathy and hypoglycaemia. This is usually
precipitated by a minor febrile illness,
particularly gastroenteritis, and fasting. Of those presenting clinically, up to a quarter will die and about a third of
survivors will have irreversible neurological damage. 3 4 In a significant proportion there is a history of previous sudden
unexplained death or encephalopathy in a sibling. 4 However, the presentation varies widely, with some individuals not
presenting until they are adults and an unknown number remaining undiagnosed or
asymptomatic. In people of northern European descent, over 80% of clinically
diagnosed patients are homozygous for one mutation
G985A. Simple heterozygotes have no symptoms. The mainstay of
treatment is a high carbohydrate diet, orally or intravenously during fasting
or intercurrent infection. 5 This seems to be effective, with few of the 162 children reported
in the two largest series having further episodes of encephalopathy. 3 6 The outcome for siblings diagnosed prospectively also seems good.6 Given this clinical course and response to treatment, medium chain
acyl CoA dehydrogenase deficiency has been identified as a potential candidate
for early detection through newborn screening. 7 8 Several centres outside the United Kingdom have introduced newborn
screening for medium chain acyl CoA dehydrogenase deficiency by using tandem
mass spectrometry to measure acyl carnitines.9 Carpenter et al have recently reported identifying 11 babies with
definite medium chain acyl CoA dehydrogenase deficiency among 275 000 screened,
a birth prevalence of 4 per 100 00010which
was lower than expected. Their publication highlights many of the questions and
uncertainties that remain about performance and outcome. Differences in the
choice of metabolite as well as in thresholds used to define a positive result
limit direct comparison of test performance between centres. A further issue is
the criteria used to confirm a diagnosis of medium chain acyl CoA dehydrogenase
deficiency. In one study from the United States 62 infants were considered to
have medium chain acyl CoA dehydrogenase deficiency solely on the basis of
"pathological acyl carnitine profiles."9 By contrast, Carpenter et al applied explicit independent
diagnostic criteria to 23 infants with positive screening results and diagnosed
definite medium chain acyl CoA dehydrogenase deficiency in 11, with one further
probable mild case.10
A striking finding in this report is that of the remaining
11 babies who screened positive but did not meet the diagnostic criteria for
medium chain acyl CoA dehydrogenase deficiency (false positives), four died in
the neonatal period. This is consistent with observations that infants and
young children who are ill for any reason may have abnormal patterns of acyl
carnitines.11
In a retrospective study based on 100 600 dried blood spots,
all but one of those with false positive results were preterm babies.12 The false negative rate is difficult to determine, as none of the
prospective studies included a rigorous scheme to identify those who might have
escaped detection. Babies who have rapidly become carnitine depleted may be
missed. It is already clear that newborn screening identifies some individuals
whose history is not known and who may be treated unnecessarily. In both the
Australian and the US study the frequency of the common mutation was lower than
expected, and the proportion of A985G heterozygotes higher. 9 10 To be maximally effective screening needs to be done and acted on
very soon after birth. Up to one third of those with medium chain acyl CoA
dehydrogenase deficiency have been reported to present in the first three days
of life,4 and this
may be an underestimate since the diagnosis is easily missed. Appropriate
samples need to be collected from all sick newborn infants, including those who
die. Detection and timely diagnosis will also depend on the age at which
screening is undertaken. In all the prospective studies reported to date the
screening specimen was collected between the second and third day of life,
considerably earlier than in the United Kingdom, where this is generally
collected between the sixth and tenth day. However, bringing forward the age at
screening in the United Kingdom may influence test performance for other
conditions that share the same screening infrastructure. Ensuring that
screening improves outcome will depend on the timely delivery of high quality
clinical services to babies and their families. This is a considerable
challenge, especially since there is a shortage of clinicians with training in
paediatric metabolic medicine. Judgments about the effectiveness of screening
need to be informed by prospective data on mortality, neurological outcome, and
cognitive function. Additionally the impact of screening and treatment on the
families of infants with true, borderline, and false positive diagnoses needs
to be taken into account. Despite increasing experience of screening for medium
chain acyl CoA dehydrogenase deficiency, there has been no report of a
systematic follow up of longer term outcome in affected infants detected by
screening. Randomised trials of screening for rare disorders are difficult, but
observational data from largescale prospective collaborative studies can
provide information on test and programme performance and clinical outcome to
guide policy decisions. 7 13 These require a coordinated strategy and resources, which have
proved difficult to secure but are vital if newborn screening programmes are to
serve infants and their families and not simply be technology led. The United
Kingdom health technology assessment programme had the foresight to commission
systematic reviews in this field in the early 1990s 7 8 and originally gave high priority to evaluating newborn screening
for medium chain acyl CoA dehydrogenase deficiency. The subsequent failure to
fund this primary research has left many stakeholders disillusioned and
frustrated.14
In the United Kingdom many newborn screening laboratories
are introducing tandem mass spectrometry to screen for phenylketonuria. It now
seems probable that acyl carnitines will be added, but once again, a screening
technology looks set to be driven by enthusiasm and opinion rather than
evidence.
James V Leonard, professor of paediatric metabolic disease. Biochemistry, Endocrinology and Metabolism Unit, Institute of
Child Health, London WC1N 1EH (J.Leonard@ich.ucl.ac.uk)
Carol Dezateux, reader in
paediatric epidemiology. Centre for Paediatric
Epidemiology and Biostatistics, Institute of Child Health
Footnotes CD
is a member of the child health subgroup of the National Screening Committee.
This editorial is written in a personal capacity and is not intended to
represent the views of this committee. CD is lead investigator, and JVL a
collaborator, in a national prospective evaluation of newborn screening for
medium chain acyl CoA dehydrogenase deficiency that has been submitted, but a
decision about funding by the Department of Health and the National Screening
Committee has been deferred.
1. Report of a work group. Using tandem mass spectrometry for metabolic disease
screening among newborns. MMWR 2001; 50: 1-34. 2. Seddon HR, Gray G,
Pollitt RJ, Iitia A, Green A. Population screening for the common G985 mutation
causing medium-chain acyl-CoA dehydrogenase deficiency with Eu-labeled
oligonucleotides and the DELFIA system. Clin Chem 1997; 43: 436-442[Abstract/Full
Text]. 3. Iafolla AK, Thompson RJ, Roe CR.
Medium-chain-acyl-coenzyme A dehydrogenase deficiency: clinical course in 120
affected children. J Pediatrics 1994; 124: 409-414[Medline].
4. Pollitt RJ, Leonard JV. Prospective surveillance study of
medium chain acyl-CoA dehydrogenase deficiency in the UK. Arch Dis Child
1998; 79: 116-119[Abstract/Full
Text]. 5. Dixon MA, Leonard JV. Intercurrent
illness in inborn errors of intermediary metabolism. Arch Dis Child
1992; 67: 1387-1391[Abstract].
6. Wilson CJ, Champion MP, Collins JE, Clayton PT, Leonard
JV. Outcome of medium chain acyl-CoA dehydrogenase deficiency after diagnosis. Arch
Dis Child 1999; 80: 459-462[Abstract/Full
Text]. 7. Pollitt RJ, Green A, McCabe ERB, Booth A, Cooper NJ, Leonard JV,
et al. Neonatal screening for inborn errors of metabolism: cost, yield and
outcome. Health Technology Assessment 1997;1. 8. Seymour CA, Chalmers
RA, Addison GM, Bain MD, Cockburn F, Littlejohns P, et al. Neonatal screening
for inborn errors of metabolism: a systematic review. Health Technology Assessment
1997;1. 9. Andresen BS, Dobrowolski SF, O'Reilly L, Muenzer J, McCandless
SE, Frazier DM, et al. Medium-chain acyl-CoA dehydrogenase (MCAD) mutations
identified by MS/MS-based prospective screening of newborns differ from those
observed in patients with clinical symptoms: identification and
characterization of a new, prevalent mutation that results in mild MCAD
deficiency. Am J Hum Genet 2001; 68: 1408-1418[Medline].
10. Carpenter K, Wiley V, Sim KG, Heath D, Wilcken B.
Evaluation of newborn screening for medium chain acyl-CoA dehydrogenase
deficiency in 275 000 babies. Arch Dis Child 2001; 85: F105-F109[Abstract/Full
Text]. 11. Clayton PT, Doig M, Ghafari S,
Meaney C, Taylor C, Leonard JV, et al. Screening for medium chain acyl-CoA
dehydrogenase deficiency using electrospray ionisation tandem mass
spectrometry. Arch Dis Child 1998; 79: 109-115[Abstract/Full
Text]. 12. Pourfarzam M, Morris A, Appleton M,
Craft AW, Bartlett K. Neonatal screening for MCAD deficiency: support from a
retospective study. Lancet 2001; 358: 1063-1064[Medline].
13. Dezateux C. Evaluating newborn screening programmes
based on dried blood spots: future challenges. Br Med Bull 1998; 54:
877-890[Abstract].
14. Tanner S, Sharrard M, Cleary M, Walter J, Wraith E, Lee
P, et al. Screening for medium chain acyl-VoA dehydrogenase deficiency has
still not been evaluated. BMJ 2001; 322: 112[Full
Text
http://bmj.com/cgi/content/full/324/7328/4
******************************
Study finds there's a
critical time for learning
all languages, including sign language
Neuroscientists examining the brain
activity of people who learned to speak American Sign Language (ASL) at
different times in their lives have found the first evidence that there is a
critical period for acquiring a non-verbal language, just as there is for
spoken languages.Using functional magnetic resonance imaging (fMRI), the
researchers discovered patterns of brain activity in bilingual people who
learned ASL before puberty differed from those who learned it after puberty.
The findings are reported in this month’s issue of the journal Nature
Neuroscience. They indicate there are regions in the brain’s right hemisphere
that are activated when children who learned ASL before puberty are reading
sign language. The brains of children who learned ASL after puberty show
significantly less right hemisphere activity when they are doing the same
activity. There is widespread acceptance among neuroscientists that there is a
critical period for first language acquisition, and that children who are not
exposed to any language before puberty, or perhaps sooner, are unable to fully
acquire and use the principles of language. There also is evidence of similar
critical periods for acquiring a second language. “We know that late learners
of ASL, while they are very fluent, never will be fully fluent like native, or
early, learners of ASL,” said David Corina, a University of Washington
associate professor of psychology and a co-author of the study. Corina is
fluent in ASL.“One aspect of ASL that is difficult for late learners is verb
signs of motion. You see some subtle errors in their use of these verbs, just
as you might detect subtle grammatical differences when listening to bilingual
users of a spoken language when they are not using their native tongue.”Other
members of the research team are Aaron Newman, a University of Oregon doctoral
student; Helen Neville, University of Oregon psychology professor; Daphne Bavelier,
assistant professor of brain and cognitive sciences at the University of
Rochester, and Peter Jezzard, a physicist at John Radcliffe Hospital in
England.The new study builds on earlier work by this research team showing that
right hemisphere activity, along with activation in the left hemisphere, is
necessary for processing ASL. The left hemisphere activity has long been
associated with the processing of spoken languages.“One area of the brain that
is the signature, or specific, to signers if they learned ASL as a native
signer, is the right angular gyrus,” Corina said. It is located at the juncture
of the temporal and parietal lobes. Activation of the left angular gyrus has
been associated with reading English and other spoken languages for many years.
The new study shows consistent activation of the right angular gyrus among
native signers and some, but not consistent, activation of that brain region
among late signers.The study involved 27 bilingual subjects. Sixteen were
hearing persons born to deaf parents. They learned ASL and English from birth
as native languages. The remaining 11 were the late learners who had English as
their native language and learned ASL after puberty, in early adulthood. All of
the subjects watched a screen while their brains were imaged using fMRI and
were asked to read written English sentences and meaningless strings of
consonants. They also were shown and asked to read ASL sentences and
meaningless gestures that were similar to real ASL signs.“This work is important
because we want to understand the neural systems underlying language,” said
Corina. “We want to know if they are malleable or fixed and the degree to which
they may vary in different languages. We now know there is activation in the
right hemisphere when native signers view ASL, and to see that this is
dependent on early exposure suggests there are specific times when neural
systems for language may be particularly sensitive to change.”He added that the
research has implications for early education of all children because it
stressed the need for early language exposure at critical times in development.
And now, it is equally important in education for the deaf to ensure linguistic
competency in ASL.
Contact: Joel Schwarz
joels@u.washington.edu
206-543-2580
University of Washington
http://www.eurekalert.org/pub_releases/2002-01/uow-sft010202.php
******************************
District evaluates full inclusion
Officials
cite progress in special education, but some parents question affects on
general education.
By Gary Moskowitz BURBANK -- The school board recently got a crash course in
its own special education program as leaders spelled out current tactics
designed to meet the needs of Burbank children with learning disabilities.
A meeting that lasted more than three hours just scratched the surface of
special education, educators said. The district's program serves 1,619 students
with 270 employees and a budget of more than $14 million in federal, state and
district funds.
The district, which has about 15,000 students, will spend almost $2 million of
its general fund on special education this year. Considering characteristics
like autism, mental retardation and impairments of hearing, vision and speech,
program director Sandy Gaynan told the board special education should be the
last resort for children, and that it must be proved that regular classroom
intervention has been unsuccessful.
"Is the child going to benefit from this? That is what we have to
establish with every student," Gaynan said.
Gaynan said 13 students are participating in full inclusion -- the placement of
special education students into general education classrooms -- and performance
has improved among many of Burbank's special education students.
For parents like Pam Reynolds, full inclusion has made a difference for her
9-year-old son, Jake, who is autistic.
"It can be too stressful for some kids and not the best idea, but it is
extremely helpful for kids who can benefit from the social interaction,"
Reynolds said.
But parents like Nancy Pierce question the effects of full inclusion on the
rest of the general education class.
"What safeguards are in place for the average classroom kid, and if you
are a kindergarten student with an autistic child in the room, how is their
education going to be altered?" Pierce asked. "It helps the handicapped
kids in later years, because they have had socialization, which is important,
but at what cost to the other students in the room?"
Pierce's concerns are somewhat assuaged by the fact that her 10-year-old son,
Matthew, has shared a class with an included special-education student for two
years and enjoys helping the student without being asked to do so.
"I usually help him, because I feel like it, and I respect him like any
other normal kid. It doesn't bother me or distract me," said Pierce's son,
Matthew. "It can be difficult, but when you put effort into it it's
worthwhile."
Reynolds maintains the more parents and educators communicate about what
strategies are successful and what goals are for the students, the more
successful programs like full inclusion will be.
http://www.latimes.com/tcn/burbank/news/la-bl0007213jan02.story?coll=la%2Dtcn%2Dburbank%2Dnews
******************************
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