Des défauts du placenta pourraient être un signe précoce d'autisme

Par Tracy Staedter, Scientific American

Les scientifiques ont découvert que le plus précoce des indicateurs d'autisme à ce jour, pourrait être la présence de cellules défectueuses dans le placenta. Cette découverte pourrait mener à un diagnostic plus précoce du trouble du développement qui touche environ un enfant sur 200 et peut avoir comme conséquence des difficultés d’apprentissage, des problèmes de parole et une difficulté dans les relations interpersonnelles.

"Plus vite nous le diagnostiquerons, plus nous le comprendrons et plus efficaces seront nos interventions," dit le chercheur scientifique Harvey Kliman, de l’Ecole de Médicine. Kliman et son équipe décrivent leur découverte dans l’édition en ligne du 26 juin de Biological Psychiatry.

Cette recherché s’appuie sur les travaux antérieurs de Kliman, qui décrivaient des crevasses anormales dans l’enveloppe externe du placenta. Dans le passé, ces anomalies ont été mises en relation avec une longue liste de défauts génétique, y compris les syndromes de Down et de Turner.

Kliman soupçonnait qu’ils pourraient aussi être lies à l’autisme. Alors, dans cette étude, lui et d’autres chercheurs de Yale ont utilise un microscope pour examiner des échantillons de tissu du placenta, conservés par plusieurs hôpitaux de recherche. Treize de ces échantillons provenaient d’enfants ayant été plus tard diagnostiqués nt une forme d’autisme; 61 échantillons provenaient d’enfants chez qui la maladie n’avait pas été diagnostiquée. Lorsque Kliman a compare les deux groupes de tissus, il s’est aperçu que les placentas des enfants autistes avait trois fois plus de chance d’avoir les crevasses microscopiques anormales.

Kliman pense que ces recherches pourront conduire à un examen de routine du placenta des nouveau-nés à risque, notamment ceux ayant un frère ou une sœur autiste. Tous les autistes n’ont pas nécessairement cet aspect anormal du placenta. Mais, dit Kliman, "Si vous observez ces défauts, il est improbable que l’enfant soit parfaitement normal."

Draw line under MMR scare, plead top doctors

· 'More children will die' unless jabs get all-clear
· Warning as England faces big measles epidemic

Ian Sample,
science correspondent
Tuesday June 27, 2006
The Guardian

A group of Britain's leading paediatricians and childhood vaccination experts has warned that more children will die unless a line is drawn under the autism and MMR (measles, mumps and rubella) vaccine controversy.

In an open letter, 30 scientists, including some of the country's most eminent child health experts, say that an overwhelming body of evidence shows the vaccine is safe. They add that urgent immunisations are necessary to prevent potentially devastating outbreaks among schoolchildren.

The warning comes as England faces its biggest measles outbreak in 20 years, fuelled by the refusal of some parents to have their children immunised because of now discredited claims linking the MMR jab and autism.

The letter, whose signatories include Patricia Hamilton, president of the Royal College of Paediatrics and Child Health, and Professor Sir David Hall, a paediatrician at Sheffield University, says: "The time has come to draw a line under the question of any association between the MMR vaccine and autism. The UK's children are in danger of serious illness or death if they are left unimmunised."

This month, the Health Protection Agency reported 449 cases of measles so far this year - more in just six months than the 438 reported cases in 2003. In 2005, there were only 77 reported cases.

Confidence in the MMR vaccine slumped in 1998 when a team led by Andrew Wakefield at the Royal Free hospital, north London, published research in the Lancet on bowel disease and autism. Dr Wakefield later suggested that there might be a link between autism and the MMR jab. He now faces professional misconduct charges brought by the General Medical Council.

In the letter, the scientists raise concerns that many children born during the height of the MMR scare are now set to enter schooling without the immunisation. "We are now faced with a potentially serious situation. Years of low uptake mean large numbers of unprotected children are now entering school. Unless this is rectified urgently, and children are immunised, there will be further outbreaks and more unnecessary deaths," it says.

Although immunisation rates are rising, they are still below the 95% level the World Health Organisation says is needed for "herd immunity". A year ago MMR uptake stood at 70.8% in London and 83% for the whole of the UK. The letter adds: "It is not too late to avert this predictable tragedy. It is time that due weight is given to the overwhelming body of scientific evidence in favour of the vaccine. Misguided concepts of "balance" have confused and dangerously misled patients. We all, media, politicians and health professionals, have a responsibility to protect the health of our children."

David Elliman, a consultant in community child health at Great Ormond Street Hospital, and a signatory of the letter, said that a vast body of research now vindicated the MMR vaccine, but he added that some media reports remained "partisan" in their coverage of research into the vaccine.

"Parents should be wary of simplistic headlines and information they read on the internet," he added.

Publish or be damned

Ben Goldacre

The Guardian

MMR is back. "US scientists back autism link to MMR," squealed the Telegraph. "Scientists fear MMR link to autism," roared the Mail. "US study supports claims of MMR link to autism," croaked the Times, a day later.

Strap me to the rocket and print my home address in the paper, I'm going after them again. So what was this frightening new data? Well it's hard to tell, since it hasn't been properly published anywhere yet. This is now standard operating procedure for all scare stories, because journalists have learnt that informed and informative public debate on unpublished research is basically impossible. So it turns out that these three stories were all about a poster presentation at a conference that had yet to occur on research not yet completed by a man with a track record of announcing research that then does not appear in academic journals.

The story is that Arthur Krigsman may have found genetic material (RNA) from vaccine-strain measles virus in some gut samples from children with autism and bowel problems. Some believe that this could implicate the vaccine in causing health problems.

But let's not forget, the Mail was promoting Dr Krigsman's research back in 2002: at that time, he was putting endoscopes into the bowels of young children with autism, and said he had found evidence of inflammation. Four years later, looking on PubMed, the standard database for all medical papers, it seems this research still has not been published in a peer-reviewed academic journal. Forgive my bluntness, but it seems a shame to go poking around up there if you're not going to write up your findings properly.

Meanwhile the Telegraph says his latest unpublished claim replicates similar work from 1998 by Andrew Wakefield, and from 2002 by Professor John O'Leary. But there is no such work from 1998 by Dr Wakefield, at least not on PubMed. Meanwhile it is well documented that other labs have tried to reproduce the 2002 study and come back with different results, and that the protocol was likely to have problems with false positives because of the tests used: two perfect examples of the importance of research being fully written up and published, so it can be replicated and assessed.

I could go on, but instead, here is the news you didn't read: in the May issue of the Journal of Medical Virology there was a similar study, only this one has actually been published. It looked for measles RNA in children with regressive autism after MMR vaccination but found no evidence of the magic vaccine-strain measles RNA to implicate MMR, and perhaps because of that unfrightening result, the study was loudly ignored by the press. Like all science in the real world it has its flaws, but because it has been published in full, I can read it, and pick holes in it.

In the spirit of science, the least opponents of MMR could do is share their data, and most importantly publish their scientific work, in full, openly, before their peers, rather than the press.

Study Shows Autism-related Developmental 'Red Flags' Identifiable At Age Two In Children

Science Daily — Early detection of autism is critical for early intervention, yet autism spectrum disorders (ASD) are typically not diagnosed until after three years of age. However, a study published today in the Journal of Child Psychology and Psychiatry found differences between typically developing children and those with ASD are detectable by two years of age. Because there are currently no medical diagnostic tests for autism, identifying developmental disruptions in infants and very young children with ASD may allow for earlier detection and critical intervention.

The study examined development in 87 infants at 6, 14 and 24 months of age using a standardized development test. Based on data and clinical judgment at 24 months, participants were classified as: unaffected, language delayed (LD) or ASD. Researchers compared development across groups at the three target ages and observed statistically significant differences between the ASD group and the unaffected group at 14 months. By 24 months, significant differences were detectable between the ASD group and both the unaffected and LD groups.

"Introducing behavioral interventions even one year earlier can make a tremendous difference in the lives of children with autism and their families," said Dr. Rebecca Landa, Director of the Center for Autism and Related Disorders at the Kennedy Krieger Institute in Baltimore, MD and lead author of the study. "If we are able to educate professionals to identify red flags in development we can then recognize and diagnose the disorder at one-and-a-half or two years of age, instead of three or four, allowing for earlier intervention and ultimately better outcomes."

Participants in the study included infants at high risk for autism (siblings of children with autism), and infants at low risk (no family history of autism). Researchers measured development using the Mullen Scales of Early Learning (MSEL), a standardized test which assesses five domains of development, including: gross and fine motor; visual reception; and receptive and expressive language. At 14 months, four of the five mean MSEL scores were significantly lower in toddlers with ASD than those in the unaffected group. By 24 months, the ASD group performed significantly worse than the unaffected group in all domains of development, and worse than the LD group in three domains. Nearly half of the ASD group showed developmental worsening between 14 and 24 months.

This study and previous research studies conducted by Dr. Landa found that developmental red flags for parents and physicians to watch for include: poor eye contact; reduced responsive smiling; diminished babbling; reduced social responsivity; and difficulty with language development, play and initiating or sustaining social interaction.

"With so many unanswered questions in the autism arena, we need to tackle this condition on many different fronts," said Dr. Gary Goldstein, President and CEO of the Kennedy Krieger Institute. "For this reason, experts at Kennedy Krieger are not only conducting early diagnosis and intervention research, but also investigating the genetic and environmental causes of autism, as well as other potential treatment options."

Autism is the fastest growing developmental disorder in the United States. This year more children will be diagnosed with autism than AIDS, diabetes and cancer combined, yet profound gaps remain in our understanding of both the causes and cures of the disorder. Increasing our knowledge about developmental disruptions in individuals with ASD is crucial, since early detection and intervention can lead to improved outcomes in individuals with ASD.

About the Kennedy Krieger Institute
Internationally recognized for improving the lives of children and adolescents with disorders and injuries of the brain and spinal cord, the Kennedy Krieger Institute in Baltimore, MD serves more than 12,000 individuals each year through inpatient and outpatient clinics, home and community services and school-based programs. Kennedy Krieger provides a wide range of services for children with developmental concerns mild to severe, and is home to a team of investigators who are contributing to the understanding of how disorders develop while pioneering new interventions and earlier diagnosis. For more information on Kennedy Krieger Institute, visit www.kennedykrieger.org.

Note: This story has been adapted from a news release issued by Kennedy Krieger Institute.