07 décembre 2008

It's not what the papers say, it's what they don't

Ben Goldacre
The Guardian

Writing this column really scares me because I wonder whether everything else in the media is as shamelessly, venally, manipulatively, one-sidedly, selectively reported on as the things I know about. But this week the reality editing was truly without comparison.

On Tuesday the Telegraph, the Independent, the Mirror, the Express, the Mail, and the Metro all reported that a coroner was hearing the case of a toddler who died after receiving the MMR vaccine, which the parents blamed for their loss. Toddler 'died after MMR jab' (Metro), 'Healthy' baby died after MMR jab (Independent), you know the headlines by now.

On Thursday the coroner announced his verdict: the vaccine played no part in this child's death. So far, of the papers above, only the Telegraph has had the decency to cover the outcome. The Independent, the Mirror, the Express, the Mail, and the Metro have all decided that their readers are better off not knowing. Tick, tock.

Does it stop there? No. Amateur physicians have long enjoyed speculating that MMR and other vaccinations are somehow "harmful to the immune system" and responsible for the rise in conditions such as asthma and hay fever. Doubtless they must have been waiting some time for evidence to appear.

This month a significant paper was published by Hviid and Melbye in the December 1 issue of the American Journal of Epidemiology. They examined 871,234 children in a Danish birth cohort, comparing asthma in those who had MMR against those who didn't. MMR-vaccinated children were massively and significantly less often hospitalised with an asthma diagnosis, and used fewer courses of anti-asthma medication than unvaccinated children. This "protective" effect of the MMR vaccine was more pronounced for hospitalisations with severe asthma diagnoses.

Those results aren't just incompatible with an increased risk of asthma following MMR vaccination, they actually support the hypothesis that MMR vaccination is associated with a reduced risk of asthma in young children. Tick, tock.

And most astonishing of all is the tale of "the Uhlmann paper", or the "O'Leary paper". This came out in 2002 and claimed to have found evidence of vaccine measles virus in tissue samples from children with autism and bowel problems, to massive media acclaim.

As I've said previously, two similar papers, by Afzal et al and D'Souza et al, in 2006 found negative results on almost the same question, and were unanimously ignored by the media (even though D'Souza actively went out of his way to show how O'Leary et al got false positives).

Stephen Bustin is professor of molecular science at Barts and the London. He examined the O'Leary lab for the court case against MMR, as an expert witness for the drug company defendants. The case collapsed, and he was unable to discuss his findings. Then he was called to give evidence in the American "autism omnibus" case against the vaccine. The anti-vaccine movement did their best to prevent this. They knew what he had found: it appears to be incontrovertible evidence that the lab was detecting false positives.

Now Bustin has finally been able to write about what he found in O'Leary's lab. He published this month. Nobody who covered the original O'Leary paper has written about it. Not a soul will.

Measles cases are rising. Middle class parents are not to blame, even if they do lack rhetorical panache when you try to have a discussion with them about it.

They have been systematically and vigorously misled by the media, the people with access to all the information, who still choose, collectively, between themselves, so robustly that it might almost be a conspiracy, to give you only half the facts.

Today, I have merely given you some small part of the other half, and next week I will move on: but know that nobody else has.

01 décembre 2008

Brain's magnetic fields reveal language delays in autism

Psychology & Sociology

Faint magnetic signals from brain activity in children with autism show that those children process sound and language differently from non-autistic children. Identifying and classifying these brain response patterns may allow researchers to more accurately diagnose autism and possibly aid in developing more effective treatments for the developmental disorder. Timing appears to be crucial. "Children with autism respond a fraction of a second more slowly than healthy children to vowel sounds and tones," said study leader Timothy Roberts, Ph.D., vice chair of radiology research and holder of the Oberkircher Family Endowed Chair in Pediatric Radiology at The Children's Hospital of Philadelphia. Roberts used a technology called magnetoencephalography (MEG), which detects magnetic fields in the brain, just as electroencephalography (EEG) detects electrical fields.

Roberts presented his findings today at the annual meeting of the Radiological Society of North America in Chicago. "The brain's electrical signals generate tiny magnetic fields, which change with each sensation, and with communication among different locations in the brain," he added.

Roberts is working to develop "neural signatures" that can link recorded brain activity to particular behaviors in children with autistic spectrum disorders (ASDs), which are characterized by impaired development in communications and social functioning. "Our hypothesis is that speech and other sounds come in too fast for children with ASDs, and their difficulties in processing sound may impair their language and communication skills," said Roberts.

Physicians already use MEG to map the locations of abnormal brain activity in epilepsy, but the technology Roberts used is one of the few MEG machines available in a dedicated pediatric facility. In the current study, the researchers evaluated 64 children aged six to 15 at The Children's Hospital of Philadelphia. Thirty children had ASDs, the rest were age-matched, typically developing control subjects.

The MEG machine has a helmet that surrounds the child's head. The researchers presented a series of recorded beeps, vowels and sentences. As the child's brain responded to each sound, noninvasive magnetic detectors in the machine analyzed the brain's changing magnetic fields.

When sounds were presented, the MEG recorded a delay of 20 milliseconds (1/50 of a second) in the brain's response for children with ASDs, when compared with healthy control subjects. "This delay indicates that auditory processing is abnormal in children with autism, and may lead to a cascade of delay and overload in further processing of sound and speech," said Roberts. "Further research may shed light on how this delay in processing sounds may be related to interconnections among parts of the brain." Other testing, measuring a response to mismatched or changed sounds, found longer delays, up to 50 milliseconds (1/20 of a second).

Because autism disorders range across a spectrum of functional abilities, explained Roberts, neural signatures based on brain responses may allow clinicians to more accurately diagnose which subtype of ASD an individual patient has. Such diagnoses may be possible at an earlier age if future studies show that such signatures are detectable in infancy—at younger ages than in the children involved in the current study. "Earlier diagnosis of ASDs may allow clinicians to intervene earlier with possible treatments," said Roberts.

Furthermore, added Roberts, if a patient's neural signature overlaps with that found in another neurological condition, such as epilepsy or attention-deficit hyperactivity disorder, for which a treatment exists, that patient may benefit from such a treatment.

15 octobre 2008

Les Français ne sont pas assez vaccinés

Les Français ne sont pas assez vaccinés et on peut s'attendre à une recrudescence de maladies telles que la rougeole, la tuberculose, la coqueluche ou l'hépatite B, ont souligné mercredi des spécialistes lors d'une séance spéciale de l'Académie de Pharmacie.

Daniel Floret, président du comité technique des vaccinations, a noté que les Français étaient "les cancres de l'Europe" pour la vaccination contre l'hépatite B, avec un taux de couverture de 30%, suite aux polémiques sur le lien avec la sclérose en plaques.

"On attend une hausse de l'incidence de la maladie", a-t-il affirmé, de nombreuses personnes non vaccinées entrant dans la période la plus "à risque" (20-30 ans).

Pour la rougeole, le taux de couverture est un peu insuffisant et on assiste à "des flambées épidémiques". Pour le BCG, l'obligation vaccinale a été suspendue mais "il faut vacciner les enfants à risque", notamment ceux d'Ile-de-France ou issus de l'immigration.

Pour la coqueluche, les bébés pas encore vaccinés risquent d'être contaminés par des adultes qui ne sont plus immunisés. Il cite ainsi le cas de "17 nourrissons" atteints à Lyon au cours de la dernière année.

Le Pr Floret a évoqué aussi les risques de grippes nosocomiales, les infirmières étant "moins vaccinées" que l'ensemble de la population. Les soignants sont peu vaccinés aussi contre la coqueluche, la varicelle ou la rougeole.

Le Pr Jean-François Bach, secrétaire perpétuel de l'Académie des sciences, a admis qu'il y avait des risques vaccinaux mais "très rares" : "bécégite", une inflammation d'après BCG, paralysies du nerf facial après administration d'un vaccin nasal contre la grippe, réactions après vaccination contre la rougeole en Afrique...

En revanche les spécialistes se sont insurgés contre les effets secondaires "non prouvés" : autisme attribué au vaccin contre la coqueluche dans les années 80 en Grande-Bretagne, diabète attribué au BCG aux Etats-Unis, sclérose en plaques liée à la vaccination contre l'hépatite B en France.

Le Pr Bach a souligné "l'énorme erreur statistique" de l'équipe menée par le Pr Marc Tardieu, qui a vu récemment une "tendance significative" à la sclérose en plaques dans un sous-groupe d'enfants traités par le vaccin. "On ne peut pas analyser des sous-groupes commes des groupes entiers", a-t-il souligné. "Le dossier est vide".

Le Pr Marc Girard, de l'Académie de médecine, a évoqué les "vaccins du futur" pour lesquels la recherche pourrait aboutir dans 5 à 10 ans, concernant par exemple la bronchiolite de l'enfant ou le paludisme. Les chercheurs travaillent aussi sur un nouveau vaccin contre la tuberculose, le BCG n'étant pas efficace chez l'adulte.

Des vaccins non plus préventifs mais thérapeutiques (une fois la maladie déclarée) contre le sida ou l'hépatite C sont envisageables à plus long terme, de même que contre des maladies non infectieuses tels cancers, Alzheimer ou athérosclérose. Mais selon le Pr Girard c'est encore aujourd'hui "un peu théorique".

04 septembre 2008

Autisme: une étude confirme l'absence de lien avec le vaccin anti-rougeole

WASHINGTON (AFP) - Une étude conduite aux Etats-Unis confirme l'absence de lien entre l'autisme et le vaccin combiné contre la rougeole, la rubéole et les oreillons ce qui, espèrent ses auteurs, va permettre de revenir à un taux normal de vaccination pour combattre des poussées épidémiques de ces infections.

Cette recherche publiée mercredi dans la version en ligne du journal Public Library of Science, a tenté de reproduire les résultats d'une étude de 1998 conduite par le Dr Andrew Wakefield du Royal Free Hospital en Grande Bretagne selon laquelle il existerait un lien entre l'autisme et ce vaccin.

Le Dr Wakefield, dont les travaux avaient alors paru dans la revue le Lancet, a depuis officiellement demandé leur rétractation.

Des chercheurs de l'Université Columbia à New York et des Centres fédéraux américains de contrôle et de prévention des maladies (CDC) ont ainsi tenté de trouver des signes de la présence de marqueurs génétiques du virus de la rougeole dans des échantillons de tissus intestinaux prélevés sur 25 enfants autistes et souffrant également de problèmes gastro-intestinaux.

Ils ont comparé ces échantillons avec ceux provenant de 13 enfants du même âge ayant aussi les mêmes troubles intestinaux mais qui ne sont pas autistes.

Les tissus ont été analysés par trois laboratoires qui ignoraient de quels enfants ils provenaient.

"Cette étude montre sans aucun doute l'absence d'un lien entre autisme et le vaccin", concluent ces auteurs.

Ils ont aussi collecté auprès des parents et des médecins traitants des données sur les antécédents médicaux de ces enfants pour déterminer si l'apparition de leur autisme ou de leurs troubles intestinaux précédaient leur vaccination.

"Nous n'avons trouvé aucun lien entre le moment de la vaccination et l'apparition de problèmes intestinaux ou d'autisme", a dit dans un communiqué le Dr Mady Horni de l'Université Columbia, l'un des co-auteurs de cette étude.

Les responsables de santé publique aux Etats-Unis insistent depuis ces dernières années sur l'absence de risque posé par ce vaccin combiné ou d'autres vaccins destinés aux enfants face à des groupes de parents affirmant que ces vaccinations pourraient être responsables de l'autisme.

Un cour fédérale américaine (U.S Court of Federal Claims), saisie par des parents, examine cette question depuis près d'un an.

L'Institut américain de médecine, qui fait autorité, a publié plusieurs rapports concluant avec certitude à l'absence de relation entre l'autisme et ces vaccins.

Le refus de nombreux parents de faire vacciner leurs enfants contre les infections infantiles a contribué au plus grand nombre de cas de rougeole aux Etats-Unis et dans certains pays européens observés depuis de nombreuses années, soulignent les CDC.

La rougeole tue environ 250.000 personnes annuellement dans le monde dont la plupart du temps des enfants dans les pays pauvres.

Selon les statistiques des CDC, un enfant sur 150 est atteint d'autisme ou du syndrome d'Asperger aux Etats-Unis.

08 août 2008

Rougeole : l'Europe voit rouge

Par Destination Santé

La rougeole envahit l'Europe. Après la Suisse et l'Autriche elle s'attaque à l'Italie et au Royaume-Uni. De l'autre côté de la Manche, 461 cas ont été enregistrés depuis le début de l'année. Les autorités italiennes ont quant à elles comptabilisé… 2 079 cas entre septembre 2007 et mai 2008 !

Une véritable flambée épidémique à laquelle jusqu'à présent, la France est épargnée. En Italie l'épidémie a débuté dans la région du Piémont, affectant essentiellement des adolescents non vaccinés. Mais 15 régions sur 21 sont désormais touchées. En cause comme toujours, une trop faible couverture vaccinale. Certes des progrès ont été réalisés mais « ils restent insuffisants » soulignent les rédacteurs d'Eurosurveillance. Selon le ministère de la Santé italien, elle était de 88% en 2006 contre 84% en 2003.

Les autorités sanitaires anglaises et galloises s'alarment pour leur part, du caractère endémique de la rougeole. A tel point qu'elles demandent à tous les services de santé de vacciner le maximum d'enfants. Une mission loin d'être évidente. Au Royaume-Uni en effet, une rumeur –démentie depuis - selon laquelle la vaccination ROR aurait été liée à l'apparition de cas d'autisme a effrayé la population en 1998. A cette date, 92% des petits Britanniques étaient immunisés. En 2003 ils n'étaient plus que 79%. Un taux de couverture qui depuis, peine à remonter.

Source : Eurosurveillance, volume 13, 3 juillet 2008 ; 17 juillet 2008

La bêtise et n'en finit pas de faire des petites victimes.

17 juin 2008

Hépatite B : la France toujours à la traîne

Par Destination Santé

Plus de 10 ans après « l'affaire » du vaccin anti-hépatite B et de son rôle supposé dans l'apparition de cas de sclérose en plaques (SEP), la France nage toujours dans ses contradictions. Onze études ont déjà écarté toute relation entre la SEP et ce vaccin… Et pourtant rien n'y fait : les Français et une partie des professionnels de santé le boudent toujours. Petit retour sur une épine dans le pied, dont un récent rapport de l'OMS ravive le piquant…

« Dix ans après, la France a encore du mal à augmenter sa couverture vaccinale contre l'hépatite B » nous explique sur un ton très diplomatique (devoir de réserve oblige !) Eric Laurent. Au bureau régional de l'OMS pour l'Europe, il est « Conseiller adjoint en charge du programme des vaccinations ». Un conseiller donc, qui rappelle à l'envi que « le rôle de l'OMS n'est certainement pas de critiquer ses Etats-Membres ».

Critiquer, peut-être pas… Mais l'Organisation sait trouver son franc-parler quand il s'agit de mettre en garde contre les risques sanitaires liés à des choix politiques hasardeux ! En 1998, elle ne s'était pas privée de dire son désaccord avec la décision – prise par Bernard Kouchner – de suspendre la vaccination systématique des adolescents contre l'hépatite B. « Vous savez, nous sommes en contact régulier avec les autorités sanitaires françaises. Mais la situation est délicate, la vaccination contre l'hépatite B est un dossier sensible en France ». Sensible et surtout explosif : avec une couverture vaccinale qui oscille entre 33% et 42%, notre pays prend le risque sérieux de laisser « filer » les cirrhoses et les cancers primitifs du foie…

Pourquoi sommes-nous les seuls en Europe à nous défier de ce vaccin, le seul encore très récemment, à protéger d'un cancer ? Pour Eric Laurent, l'affaire est entendue : c'est la campagne de vaccination de masse lancée contre l'hépatite B en 1997 qui serait en cause. « C'est connu, les populations établissent très facilement un lien de cause à effet entre un vaccin et un effet secondaire. En revanche, défaire ce lien est une entreprise beaucoup plus longue et difficile. Il y a un grand travail d'information à fournir de la part des autorités ».

Aussi bien en direction du public, que des professionnels de santé ? « Oui, tout à fait, il est impératif d'avoir une position claire sur le sujet. La France devrait peut-être lancer une vaste campagne médiatique afin de rassurer une fois pour toute ses citoyens quant à l'innocuité du vaccin. A l'instar de celle qui a été menée en Grande-Bretagne il y a 4 ans. Elle avait alors permis de réconcilier les Anglais avec le vaccin ROR ».

Source : Bulletin de l'OMS, 6 juin 2008 ; interview d'Eric Laurent, Conseiller adjoint en charge du programme des vaccinations, OMS/Europe, 13 juin 2008

"Contre la stupidité, les dieux eux-mêmes luttent en vain" écrivait Schiller. Après "l'affaire" (inexistante) du ROR, "l'affaire" toujours aussi inexistante du vaccin de l'hépatite B n'en finit pas de faire des victimes... de la bêtise humaine.

06 mai 2008

Vaccin rougeole et autisme: aucune évidence scientifique

Genève, 2 mai - L'hypothèse d'un lien entre la vaccination rougeole et l'autisme a été lancée en 1998 par Wakefield. Des millions de dollars ont été investis pour étudier cette hypothèse effrayante. Le verdict est tombé en 2001: il n'y a aucune évidence scientifique soutenant cette hypothèse. Si la vaccination était une cause d'autisme, le nombre d'autistes augmenterait lorsque la vaccination est introduite dans un pays ou que la proportion d'enfants vaccinés augmente: ce n'est pas le cas, puisque l'autisme continue à augmenter même quand la vaccination rougeole diminue! Si la vaccination était une cause d'autisme, les enfants non vaccinés devraient avoir un risque d'autisme plus faible que les enfants vaccinés: ce n'est pas le cas, l'autisme touchant un enfant sur 100-150, vaccinés ou non.

Si la vaccination était un facteur déclenchant de l'autisme, les problèmes devraient apparaître plus souvent après qu'avant un vaccin: ce n'est pas le cas, puisque les troubles régressifs commencent après le vaccin chez 16% des enfants et avant le vaccin chez 18% d'entre eux. En 2004, une enquête a révélé que Wakefield avait été grassement payé par des avocats espérant intenter un procès aux producteurs. Même sa pseudo-démonstration de résidus de vaccin dans les intestins d'enfants autistes a été invalidée. En 2008, affirmer que ses travaux ont été vérifiés est un mensonge et accuser tous les autres chercheurs d'être manipulés par l'industrie est ridicule. En 2008, affirmer que la vaccination ROR provoque l'autisme c'est nier volontairement toutes les évidences. Répéter une croyance personnelle, même émotionnelle, ne suffit pas à la rendre juste et détourne l'attention des vrais défis. Les enfants autistes et leurs parents méritent plus de considération: ils ont le droit que les recherches s'orientent vers les causes réelles de leurs souffrances.

Professeur François Ansermet, médecin-chef du Service Psychiatrie de l'enfant et de l'adolescent HUG, et professeur Claire-Anne Siegrist, médecin adjoint et directrice du Centre de vaccinologue de la Faculté de médecine de Genève.

28 mars 2008

Doctor in MMR row defends stance at disciplinary hearing

Three deny serious professional misconduct
Clinical care of children main concern, GMC told

* Karen McVeigh
* The Guardian

The doctor who first sparked widespread safety fears over the MMR vaccine said yesterday that his paramount concern was "clinical care" for children who had developed autism after being vaccinated.

Giving evidence for the first time at a General Medical Council disciplinary hearing, where he is accused of serious professional misconduct, Dr Andrew Wakefield also denied he was motivated by an interest in litigation. He defended the way he carried out research which caused national controversy and a drop in vaccine rates.

Claims against Wakefield, 51, and two other doctors relate to investigations for their study on 12 children with bowel disorders carried out between 1996 and 1998. It is alleged Wakefield accepted £50,000 for research to support parents' attempts to fight for compensation.

Wakefield said: "In a research capacity, I was fascinated by the possibility that something could be done to help those children in their plight, but it was secondary to getting help for them. The reason those parents were contacting me was nothing to do with litigation."

Wakefield, a senior lecturer and academic who admitted at the hearing he had no knowledge of autism, nor any qualifications in paediatrics or pathology, also denied submitting young children to a series of painful tests in an attempt to stand up his hypothesis.

He said he had "no role whatsoever in determining clinically whether those tests should or shouldn't take place". He said all the tests were ordered by Professor John Walker-Smith, one of his co-accused. He referred to Walker-Smith as "one of the most eminent paediatric gastroenterologists in the world".

Earlier, Wakefield and his wife, Carmel, were cheered by about 60 supporters as they arrived at the hearing in central London.

Wakefield said he first published a paper on a possible link between the measles vaccine and inflammatory bowel problems such as Crohn's disease in 1995, after which he received calls from parents, beginning with the mother of "child two". He said she told him a "compelling story" - that she believed her child had developed autism after receiving the MMR vaccine.

Wakefield, who resigned from the Royal Free hospital in north London over the row, now works at the Thoughtful House Centre for Children in Austin, Texas.

Wakefield, Walker-Smith and the third defendant, Professor Simon Murch, all deny serious professional misconduct. The hearing continues.

17 mars 2008

Autismes et vaccin: le retour

(Agence Science-Presse)

On croyait la controverse sur l’autisme morte, eh bien la voilà qui resurgit par la façade politique.

Maintes fois avancé, le lien entre vaccination et autisme constitue un mythe. Toutes les hypothèses qui ont été proposées, comme la présence de mercure, se sont révélées, après examens, sans fondements.

Or, voilà que le gouvernement américain rallume le feu. Au début du mois, on apprenait que celui-ci allait compenser un couple de Georgie qui alléguait que l’autisme de sa fille, Hannah, aujourd’hui âgée de 9 ans, avait été causé par les vaccins qui lui ont été administrés en 2000.

La décision du gouvernement ne dit pas spécifiquement que ces vaccins ont causé l’autisme, mais que les vaccins auraient « aggravé » un trouble cellulaire déjà existant —un trouble au niveau des mitochondries. Les experts interrogés un peu partout se sont dit stupéfaits —et inquiets de l’impact que cela pourrait avoir sur les campagnes de vaccination, avec tous les risques que cela entraînerait pour la santé publique. Le ministère de la Santé a refusé de commenter, et les documents relatifs à la décision n’ont pas été rendu publics.

Quelque 5000 autres familles ont déposé des plaintes similaires. Le quotidien Atlanta Journal and Constitution parle de deux autres familles qui ont déposé des plaintes similaires à celle de la famille d’Hannah, pointant du doigt le thimérosal, un des composés du vaccin à base de mercure, comme étant la cause de l’autisme. Ces deux causes doivent arriver en cour en mai.

Or, la piste du thimérosal a bel et bien été fouillée ces dernières années. Au Danemark, le thimérosal avait été éliminé des vaccins infantiles dès 1992. Une étude menée dans ce pays au début des années 2000 a révélé qu’après 1992, le nombre de cas d’autisme a... continué de grimper. Cette année encore, trois études distinctes ont échoué à trouver un lien entre thimérosal et autisme. L’une d’elles, publiée en janvier dans les Archives of General Psychiatry, a révélé qu’après le retrait du thimérosal des vaccins administrés en Californie, le taux d’autisme n’a pas baissé... là aussi, il a continué d’augmenter!

L’augmentation pourrait être une affaire de diagnostic. Il y a longtemps qu'on ne parle plus d’un autisme, mais de plusieurs degrés d’autisme, et les diagnostics se sont considérablement raffinés depuis l'époque où ces enfants étaient confondus avec les déficients mentaux.

L’autisme est un problème neurologique dont on ignore la cause; elle pourrait être génétique. Les symptômes n’apparaissent pas clairement avant l’âge de 3 ans —soit quelques mois après la vaccination contre la rougeole et la rubéole. Plusieurs médecins croient que c’est la raison pour laquelle tant de parents font spontanément ce lien.

Leaky gut autism theory doubted

BBC News

Children with autism do not appear to leak damaging proteins from their intestines, a study into the so-called "leaky gut" theory has suggested.

It has been claimed autistic children cannot fully digest proteins found in many foods - and that the resulting peptides escape and affect the brain.

But UK researchers found children with autism did not have more peptides in their urine than a control group.

They have published their findings in the Archives of Diseases in Childhood.

The "leaky gut" theory is based in part on the idea that vaccines such as MMR - given to immunise against measles, mumps and rubella - damage the wall of the intestines.

This causes the digestive problems which lead to the production of peptides, the theory goes.

To try to counter the effects of this, some parents of autistic children then reduce the amount of proteins such as gluten - found in wheat, oats, rye and barley - and casein - found in dairy products, such as milk, cheese and yogurt - in their child's diet.

Looking for a cure

But a team from Great Ormond Street Hospital, Guy's and St Thomas' Hospital and the University of Edinburgh have found no evidence of a higher level of peptides in the urine of autistic children.

They looked at 65 boys with autism and 158 without.

"It is very distressing to have a diagnosis of autism, a lifelong condition. Many families are driven to try out interventions which currently have no scientific basis," said Dr Hilary Cass of Great Ormond Street.

"Advocates of the leaky gut theory offer children a casein and gluten-free diet which as yet lacks an evidence base. Our research throws serious scientific doubt on the putative scientific basis of that diet."

But Paul Whiteley of the Autism Research Unit at Sunderland University said while the study appeared to have ruled out one reason why a gluten and casein-free diet may work, that did not mean it was not effective for some sufferers.

"It is very good news that more research is being carried out in this area. But evidence suggest that the diet does have beneficial effects for a proportion of those with autism, many of whom do suffer from bowel problems," he said.

"We need further investigation to find out if there are other reasons why it may work."

Benet Middleton of the National Autistic Society said there was an "urgent need" for more research into the efficacy of special diets for thos with autism.

"We are aware of anecdotal support for some dietary interventions, particularly those involving the exclusion of wheat and dairy products," he said.

"There is limited evidence about whether or not these diets are effective and concerns have been raised about their unregulated use."

12 février 2008

Some cases of autism may be traced to the immune system of mothers during pregnancy

UC-Davis discovery could lead to prenatal identification and prevention

(SACRAMENTO, Calif.) – New research from the UC Davis M.I.N.D. Institute and Center for Children’s Environmental Health has found that antibodies in the blood of mothers of children with autism bind to fetal brain cells, potentially interrupting healthy brain development. The study authors also found that the reaction was most common in mothers of children with the regressive form of autism, which occurs when a period of typical development is followed by loss of social and/or language skills. The findings, to be published in the March 2008 issue of Neurotoxicology, raise the possibility that the transfer of maternal antibodies during pregnancy is a risk factor for autism and, at some point, that a prenatal test and treatment could prevent the disorder for some children.

“While a growing body of research is dedicated to finding distinctions in the immune systems of children with autism, this is one of the first studies to identify immunological factors in mothers that could be linked to autism in the very earliest stages of life,” said Judy Van de Water, senior author of the study and professor of rheumatology, allergy and clinical immunology. “Our results should lead to more research on the prenatal environment and the onset of autism. We are also optimistic that in the future a prenatal test and therapeutic intervention preventing IgG exposure during pregnancy could protect some children from ever getting autism.”

Van de Water and her team began their research with blood samples from 123 mothers – 61 whose children have autism and 62 whose children are typically developing. They isolated IgG antibodies from the samples then exposed the antibody to fetal brain tissue by western blot analysis, which detects antibody reactivity to proteins. The outcome revealed a highly specific reactivity pattern to two fetal brain proteins in seven of the 61 samples from the autism group, six of which were from mothers of children who had regressive autism. None of the IgG samples from mothers in the control group produced this same result.

“We’re not entirely sure why the IgG response against fetal brain proteins was so specific for later onset autism,” said Van de Water. “It’s possible that early exposure to maternal antibodies sets in motion a biological path to autism with the behavioral outcomes not apparent until much later. It’s also possible that an environmental exposure sometime after birth could be required to set this process in motion. We are hopeful that this study will help build our understanding of the foundations of the regressive form of the disorder.”

Characteristic features of autism – social deficits, language impairments and limited, repetitive behaviors – are often clear early in an affected child’s life. Other children seem to progress normally until 12-to-24 months of age, when developmental milestones disappear. These distinct pathways have led clinicians to identify autism as one of two types – early onset or regressive – potentially with distinct causes and disease processes.

IgG antibodies are responsible for long-term immune system responses to infection, but they can also contribute to autoimmune diseases such as arthritis, multiple sclerosis and lupus. IgG also crosses the placenta in order to provide key immune system protectants to a growing fetus and newborn child, which is a key reason why Van de Water decided to investigate the role of IgG as a potential factor in autism.

Van de Water next wants to know if IgG in women during the time of their pregnancies produces the same response to fetal brain proteins. Women in the current study were two-to-five years beyond childbirth. She will now conduct the same study with women who are pregnant and already have a child with autism, because such women are much more likely to have another child with the disorder.

“If women in this next phase of the study give birth to a child eventually diagnosed with autism, blood analyses from all stages of her pregnancy will give us a clear picture of the immune system factors that were in play during gestation and could have altered her child’s neurodevelopment,” Van de Water said.

Other key next steps are to identify the specific proteins targeted by autism-specific maternal antibodies and their role in neurodevelopment and to determine whether or not exposure to maternal IgG during pregnancy leads to behavioral or social distinctions in offspring. Animal model studies are now under way to help answer these questions.

“Our outcome leads autism science in many new and exciting directions,” said Daniel Braunschweig, pre-doctoral fellow of immunology in the Van de Water lab, lead author of the current study and recent recipient of an Autism Speaks mentor fellowship to further pursue this research. “We now know we should be looking for the clues to the onset and pathology of autism much earlier than was initially assumed. Future studies should consider the immune system interactions between mother and child as a focal point in creating greater understanding of, and eventually finding effective preventions for, this complex neurodevelopmental disorder.”

“This finding is important because it provides important clues about the potential maternal contributions to autism risk in a subset of children who may develop autism,” said Isaac Pessah, director of the UC Davis Center for Children’s Environmental Health and professor of molecular biosciences. “We’re determined to find out what causes autism. Studies conducted in the Van de Water lab are giving us valuable insights as to when and where in the developmental process we should be looking for those causes.”

“We’re very interested in understanding the underlying causes of autism,” said Cindy Lawler, scientific program director at the National Institute of Environmental Health Sciences. “This finding, in combination with other new research findings coming from NIH-funded studies, demonstrates the complexity of this disorder and underscores the importance of understanding how the mother’s immune system can influence early brain development.”


The study, “Maternally Derived Antibodies Specific for Fetal Brain Proteins,” was funded by the National Institutes of Environmental Health Sciences, the U.S. Environmental Protection Agency and the M.I.N.D. Institute. A copy can be requested from newsroom@elsevier.com or downloaded at www.sciencedirect.com.

The UC Davis M.I.N.D. (Medical Investigation of Neurodevelopmental Disorders) Institute is a unique collaborative center that brings together clinicians, scientists, parents and educators for research on causes, treatments, preventions and cures for autism, fragile X syndrome, Tourette’s syndrome, attention-deficit/hyperactivity disorder and other neurodevelopmental disorders. For more information, visit www.mindinstitute.org.

The UC Davis Center for Children’s Environmental Health and Disease Prevention is a multi-disciplinary research effort established to examine how toxic chemicals may influence the development of autism in children. Toward that goal, the center is conducting two large-scale research projects: the Childhood Autism Risks from Genetics and the Environment (CHARGE) study and Markers of Autism Risk in Babies—Learning Early Signs (MARBLES) study. For more information, visit www.vetmed.ucdavis.edu/cceh.

Editor’s note: B-roll of blood sample processing for immunological studies of autism in the Van de Water lab is available on request.

05 février 2008

MMR links to autism dismissed by huge study

Sarah Boseley, The Guardian

There is no evidence to link the MMR vaccination to autism in children, according to a substantial new study published today.

In the biggest review conducted to date, scientists from Guy's Hospital in London, Manchester University and the Health Protection Agency, analysed the blood from 250 children and concluded that the vaccine could not be responsible.

The study, which was funded by the Department of Health and is published in the journal Archives of Disease in Childhood, was initiated five years ago and comes a decade after a scare about the vaccination - which protects against mumps, measles and rubella - led to a big drop in the number of children given the jab.

The theory put forward by Dr Andrew Wakefield and colleagues was that the measles virus in the MMR caused bowel disorder and subsequently autism.

However, the blood samples taken from all the children in today's study did not support that analysis. The research specifically looked for traces of measles virus in the blood of 250 children who had been given the MMR vaccination, 98 of whom had an autistic spectrum disorder.

The scientists found no difference in levels of measles virus or antibodies between those who had been diagnosed with autism and those who had not.

The tests also showed no signs of bowel disorders developing either.

The children, aged about 10 years old, had been given the first MMR jab but not all had the booster. The researchers found that those with autism or learning difficulties tended not to have had the second jab, which they say is of concern.

Professor David Salisbury, director of immunisation at the Department of Health, said: "It's natural for parents to worry about the health and wellbeing of their children and I hope this study will reassure them that there is no evidence linking the MMR vaccine to autism."

Public health experts will be hoping this study can lay to rest the controversy.

The Department of Health stressed the quality of the study and in a statement said it had "linked very careful assessment and diagnosis of a child's condition, with expert analysis of blood samples".

27 janvier 2008

Dental Tooth Fillings Containing Mercury Don't Affect Children's Brain Development, Study Suggests

ScienceDaily (Jan. 27, 2008) — Dental amalgam tooth fillings do not adversely affect children's brain development and neurological status, researchers report in the February issue of The Journal of the American Dental Association.

The authors of the report—members of a joint team from the University of Lisbon, Portugal, and the University of Washington, Seattle—studied the possible neurological effects of dental amalgam tooth restorations. Dental amalgam contains elemental mercury combined with other metals such as silver, copper, tin and zinc to form a safe, stable alloy. Dental amalgam has been used for generations to fill decayed teeth that might otherwise have been lost.

Beginning in 1997 and continuing for seven years, the authors studied 507 Portuguese children aged 8 through 12 years who received either amalgam or resin-based composite fillings. They conducted routine clinical neurological examinations to assess two types of neurological signs: hard (indicating damage to specific neural structures) and soft (subtle signs of central nervous system dysfunction that likely point to immature sensory-motor skills rather than to any structural damage in the brain). The researchers also evaluated the children for presence of tremor.

After seven years, the two groups of children did not differ in terms of the presence or absence of hard signs or tremor. They also didn't differ in terms of the presence or absence or severity of soft signs at any point. Also, as expected in healthy children, the severity of any neurological soft signs diminished as the children aged.

"Even at the levels of amalgam exposure in this study (a mean of 7.7-10.7 amalgam surfaces per subject across the seven years of follow-up)," the authors write, "[we] conclude that exposure to mercury from dental amalgam does not adversely affect neurological status.

"These data indicate the absence of a generalized negative effect on children's nervous system functions stemming from the presence of dental amalgam," they continue, "and while we cannot rule out potential adverse reactions in individual children, we found no indications of any."

JADA, a monthly journal, is the ADA's flagship publication and the most widely read scientific journal in dentistry.

Adapted from materials provided by American Dental Association.