Rougeole, oreillons et rubéole: un vaccin calomnié par profit

Sciences - Le médecin britannique selon qui le vaccin combiné rougeole, oreillons, rubéole pourrait provoquer l’autisme était à la solde d’avocats qui voulaient intenter un procès collectif.

Anne-Muriel Brouet

Le vaccin combiné rougeole, oreillons, rubéole (ROR) ne provoque pas l'autisme. Une association entre les deux est non seulement fondée sur des études grossièrement biaisées mais encore le résultat d'une stratégie visant à intenter une action en nom collectif (class action) contre les fabricants du vaccin, révèle l'enquête d'un journaliste du Sunday Times *.

Pire, un fonds d'aide juridique britannique, public, a versé plus de 8,5 millions de francs à des chercheurs et médecins pour accréditer cette thèse en vue de ce procès, aujourd'hui abandonné.

La bombe explose en février 1998. Le triple vaccin ROR provoquerait un nouveau type d'autisme, combinant troubles gastriques et syndrome régressif, selon une étude parue dans la revue médicale de référence britannique The Lancet. Dans une conférence de presse, donnée à l'époque, l'auteur de l'étude, Andrew Wakefield, plaide pour une vaccination séparée des trois maladies.

L'autisme étant une maladie aux causes mal connues, la communauté médicale aussi bien que les parents s'inquiètent. La vaccination ROR chute drastiquement en Grande-Bretagne tandis que la polémique s'étend à l'Europe et aux Etats-Unis.

Les études se multiplient dans le monde pour confirmer ou infirmer cette hypothèse. En 2002, le doute est levé: il n'y a aucun lien entre les deux choses.
Et pour cause, démontre l'enquête de Brian Deer. Derrière Andrew Wakefield, il y a un avocat, Richard Barr, à la recherche d'une class action.

Depuis 1996, il paie grassement Wakefield pour trouver la faille dans le ROR. Pourquoi lui? Le médecin londonien a déjà publié un article, dans The Lancet, sur un lien éventuel entre inflammation de l'estomac et infection virale persistante, due au vaccin contre la rougeole. Bien que cette thèse ait été infirmée, il poussera l'idée en soutenant que ces troubles digestifs modifient la perméabilité intestinale. Du coup, les toxines passent dans le sang et causent des lésions neuronales, provoquant l'autisme. C.Q.F.D.

L'objectif est plus large.

Wakefield, qui travaille à la Royal Free Medical School, a des projets qui pourraient rapporter gros: un vaccin unique contre la rougeole et des médicaments contre les problèmes gastriques et l'autisme.

Barr paye Wakefield au prix fort. Le médecin trouve parmi ses patients 12 enfants qui souffrent de troubles gastriques et d'autisme. Il nourrit ainsi son hypothèse et publie son article en 1998. D'autres, aux données biaisées, suivent.

Auditions en juillet

Parallèlement, les parents des «victimes» sont candidats à l'action collective menée par Barr. Ils seront rejoints par 1600 personnes. Durant 10 ans, la Commission des services légaux (LSC) arrose des chercheurs – beaucoup d'associés, partenaires commerciaux et employés de Wakefield – pour fournir des expertises, rapporte encore le journal britannique. Le médecin lui-même recevra un million de francs d'argent public.

Après avoir soutenu les travaux du Britannique durant six ans, The Lancet admet son erreur, en 2002. Aujourd'hui, le Conseil général médical de Grande-Bretagne a ouvert une enquête sur Andrew Wakefield qui se traduira par des auditions dès le mois de juillet. Quant à la LSC, qui gère un budget de plus de 3 milliards pour rendre la justice accessible aux défavorisés, elle a reconnu que son action contre le ROR était «ni efficace ni appropriée», rapporte le Sunday Times. Elle devra aussi vraisemblablement rendre des comptes.

* L'enquête complète de Brian Deer se trouve sur le site:
briandeer.com/mmr/lancet-summary.htm

Activation Of Brain Region Predicts Altruism

Science Daily — Duke University Medical Center researchers have discovered that activation of a particular brain region predicts whether people tend to be selfish or altruistic.

"Although understanding the function of this brain region may not necessarily identify what drives people like Mother Theresa, it may give clues to the origins of important social behaviors like altruism," said study investigator Scott A. Huettel, Ph.D., a neuroscientist at the Brain Imaging and Analysis Center.

Results of the study appear Sunday, Jan. 21, in the advance online edition of Nature Neuroscience and will be published in the February 2007 print issue of the journal. The work was funded by the National Institutes of Health.

Altruism describes the tendency of people to act in ways that put the welfare of others ahead of their own. Why some people choose to act altruistically is unclear, says lead study investigator Dharol Tankersley, a graduate student in Huettel's laboratory.

In the study, researchers scanned the brains of 45 people while they either played a computer game or watched the computer play the game on its own. In both cases, successful playing of the game earned money for a charity of the study participant's choice.

The researchers scanned the participants' brains using a technique called functional magnetic resonance imaging (fMRI), which uses harmless magnetic pulses to measure changes in oxygen levels that indicate nerve cell activity.

The scans revealed that a region of the brain called the posterior superior temporal sulcus was activated to a greater degree when people perceived an action -- that is, when they watched the computer play the game -- than when they acted themselves, Tankersley said. This region, which lies in the top and back portion of the brain, is generally activated when the mind is trying to figure out social relationships.

The researchers then characterized the participants as more or less altruistic, based on their responses to questions about how often they engaged in different helping behaviors, and compared the participants' brain scans with their estimated level of altruistic behavior. The fMRI scans showed that increased activity in the posterior superior temporal sulcus strongly predicted a person's likelihood for altruistic behavior.

According to the researchers, the results suggest that altruistic behavior may originate from how people view the world rather than how they act in it.

"We believe that the ability to perceive other people's actions as meaningful is critical for altruism," Tankersley said.

The scientists suggest that studying the brain systems that allow people to see the world as a series of meaningful interactions may ultimately help further understanding of disorders, such as autism or antisocial behavior, that are characterized by deficits in interpersonal interactions.

The researchers are now exploring ways to study the development of this brain region early in life, Tankersley said, adding that such information may help determine how the tendencies toward altruism are established.

C. Jill Stowe, a decision scientist in Duke's Fuqua School of Business, also participated in the research.

Note: This story has been adapted from a news release issued by Duke University Medical Center.

Ped Med: Autism tied to neural 'cracks'

By LIDIA WASOWICZ

SAN FRANCISCO, Jan. 15 (UPI) -- In prying beneath the brain surface of autistic patients, researchers have discovered "cracks" in a system of nerve cells called mirror neurons, which under normal circumstances permit people to see a clear reflection of the actions of others and respond appropriately to them.

Electroencephalograph, or EEG, recordings of 10 individuals with autism revealed that their mirror neurons -- also dubbed "monkey-see, monkey-do" cells -- responded only to their own doings, not to those of others, scientists said.

First identified in the early 1990s in macaque monkeys (hence their nickname), these nerve cells in the premotor cortex -- a movement-controlling brain region -- fire up both when a monkey performs an action and when it sees others imitating it.

Scientists are unable to directly study the counterpart of these nerve cells in people because they cannot be implanted with electrodes for experimental purposes. However, researchers have deduced the presence of a mirror neuron system through indirect brain-imaging measures, such as the EEG.

It now appears these cells have a greater role than previously thought.

A study in the Jan. 6 issue of Nature Neuroscience journal indicates they are involved not only in the execution and observation of movement, but also in higher cognitive processes. These include speaking, imitating and learning from the action of others, by deciphering their intentions and empathizing with their pain.

Because all these abilities come up short in most individuals with autism, scientists have suspected there may be a glitch.

New findings lend substantial support to that theory, providing evidence of a dysfunctional mirror neuron system that may contribute to many impairments, particularly those involving comprehending and responding to the behavior of others, said lead author Mirella Dapretto, assistant professor in residence of psychiatry and biobehavioral sciences at the Semel Institute for Neuroscience and Human Behavior and the David Geffen School of Medicine at the University of California-Los Angeles.

The study sheds new light on the neural basis of autism and may pave the way to early diagnosis and potential therapies, such as biofeedback, the authors said.

The investigators have already experimented with several brain-computer interface techniques that, for example, teach participants in four to six hours how to move a paddle in a computer game simply by imagining the action.

Another possibility might be to use mirrors to "trick" autistic brains into perceiving their own body's reflected movements -- to which they already respond -- as those of another being, scientists said.

Researchers have had some success in using this strategy to treat amputees who feel pain or paralysis in their missing leg or arm. Using a mirror to reflect the healthy limb, they were able to make the brain believe it was the "phantom" appendage fully restored.

It appears a breakdown in this neural network can hinder a child's ability to see and react to not only the movements but also the feelings of others, a skill crucial for social interactions.

This "crack" in the neuron mirror system may be at the root of such hallmarks of autism as difficulty in communicating, interacting, imitating and empathizing, scientists speculate.

"Together with other recent data, our results provide strong support for a mirror neuron theory of autism," Dapretto said. "This is exciting because we finally have an account that can explain ... all core deficits seen in this disorder, including impairments in social communication/interaction, 'theory of mind,' empathy, imitation and even stereotyped/repetitive behaviors."

Using a cutting-edge screening tool called functional magnetic resonance imaging, which gives researchers a front-row view of the brain's inner workings, Dapretto and her team measured the cerebral activity of 10 children with autism and 10 without the disorder. The study participants looked at 80 photographs of faces depicting anger, fear, sadness, happiness or neutrality.

The scientists found a striking contrast between the two groups, even though both were in the same age and IQ range.

Although the autistic children were able to watch and imitate the facial gestures, the pars opercularis of their inferior frontal gyrus -- a brain region near the temple that houses the mirror neurons -- failed to fire up as it was supposed to during the exercise.

In fact, the researchers said they found an inverse relationship: the less the cerebral activity, the greater the child's impairment.

In addition, all was abnormally still in the brain's emotional centers that are involved in understanding others' states of mind, which should have been humming with activity, the scientists said.

The results add validity to the hypothesis that the mirroring mechanism underlies the understanding of and response to the feelings of others -- and that its breakdown can derail an autistic child's capabilities to interact socially, the authors said.

While the investigators worked with high-functioning children on the less-impaired end of the autism spectrum, Dapretto believes the findings can apply to the entire continuum.

As is typical of scientific ventures into the unknown, the study leaves off at a critical juncture that will require further exploration.

"The question of why this system would be impaired is the billion-dollar question," Dapretto said. "If we knew this, we would be in a much better place in terms of developing successful intervention strategies or even a cure for this disorder."

Her best guess puts the blame on both nature and nurture.

"My hunch is that this is very likely to happen ... in development," she said in an e-mail message.

While nobody has any clear-cut evidence of mirror neuron functioning in neonates, the imitation seen in newborn babies can certainly suggest that this system is functional at birth, at least for some type of actions, such as mouth and facial movements that babies had a chance to practice in the womb, she said.

(Note: In this multi-part installment, based on dozens of reports, conferences and interviews, Ped Med is keeping an eye on autism, taking a backward glance at its history and surrounding controversies, facing facts revealed by research and looking forward to treatment enhancements and expansions. Wasowicz is the author of the new book, "Suffer the Child: How the Healthcare System Is Failing Our Future," published by Capital Books.)

Next: Autism at the nature-nurture nexus

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UPI Consumer Health welcomes comments on this column. E-mail: lwasowicz@upi.com

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