Wednesday, February 10, 2010

Vaccine study discredited, parent fears remain


Last week the prestigious medical journal The Lancet retracted a controversial 1998 study that linked the measles, mumps and rubella (MMR) vaccine to autism. The paper had fueled parent fears about the vaccine, leading to a sharp drop in vaccination rates. The Lancet retraction came after a British medical panel found lead author Dr. Andrew Wakefield "dishonest" and "irresponsible" in his biased selection of patients. In one of numerous ethical breaches, Dr. Wakefield paid children at his son’s birthday party to have blood drawn for the research. Yet parent activists like Jenny McCarthy heralded the news by insisting Dr. Wakefield is a hero. I interviewed Dr. Evdokia Anagnostou (above), a child neurologist who leads a clinical research program in autism at Bloorview, to understand why.

Me: Why was The Lancet retraction important?

Dr. Evdokia Anagnostou: For some time we've known this isn't a credible paper. Ten of the 13 authors had renounced the study's conclusions, no one could replicate the findings in outside labs and epidemiological studies from many countries have shown no association. But we don't retract papers because we get false positives. The retraction was based on ethical misconduct. We hope it will add to the growing body of evidence that there's no link between the MMR vaccine and autism. The concern for me is that we've been communicating that the data is inconsistent with the original study for years, and haven't been able to change the mindset of many in the autism community.

Me: Was the Wakefield paper the study that sparked the vaccine scare?

Dr. Evdokia Anagnostou: The media would like us to say this bad paper started the anti-vaccine culture. But the truth is that there's an anti-vaccine culture that is much bigger than autism. This paper found a home in that culture and had huge implications within the autism community, where parents were less likely to vaccinate their next child.

Me: Why do parents remain convinced that vaccines cause autism?

Dr. Evdokia Anagnostou: I think it's a devastating disorder, we agree on that. The truth is that research into the etiology of autism hasn’t been productive. We haven't found true etiological agents for autism. So we have models that say there's an increased genetic susceptibility that interacts with other genes or the environment to increase the expression of autism. But we haven't proven those models. For the parents of a child with a devastating illness, the hypothesis of a concrete, environmental agent – a vaccine – causing their child's condition is a very attractive proposition. People have strong emotional attachments to a hypothesis that there is one evil, outside cause that is identifiable and associated with ‘Big Pharma.’ And because the first symptoms of autism occur when most kids get their first MMR it’s easy to make the association.

Me: I think in our culture we struggle to accept that random things happen.

Dr. Evdokia Anagnostou: There is randomness to the combination, or degree of expression, of genes that can turn a functional personality trait into a condition of dysfunction like autism. In most cases, good traits that have served parents well are passed on in bad combinations. There is a reason autism is not disappearing. A detailed, systematic approach to life is a positive trait in today’s society – it makes for good scientists, bridge engineers and computer scientists. Autism is what happens when those good traits get expressed more than they should be, or in the wrong combination. For example, being very detailed-oriented and double checking your calculations to make sure that you are correct is a functional trait. But if over-expressed, this characteristic can look like compulsive behavior and all-encompassing interests to the exclusion of anything else in life. It’s not a case of passing on bad traits – which is a common misunderstanding of genetics – and is why many parents are averse to a genetic etiology to autism.

Me: Will we ever understand the cause of the genetic component of autism (why the genes get mixed in the wrong combinations) in a way that we could alter it? Is research focused on that now?

Dr. Evdokia Anagnostou: With very few exceptions, genes are inherited from mom and dad in a random fashion. Current genetics research is focused on what genes may produce susceptibility to autism and, in very rare circumstances, cause autism. At the same time, a whole new stream of research is looking at differences in the expression of genes in children with and without autism. This is of interest because it’s an area where environmental agents could interact with genes to change their expression. But so far we have not identified a single agent for autism. The question of whether vaccines could change something in your immune system that alters the expression of genes wasn’t a ridiculous hypothesis, but we haven’t found any link. The brain abnormalities we see in kids with autism – such as neurons not migrating to the right place in the brain – are ones that happen in utero, not post birth. The question is: Is it possible to have this brain abnormality and not express autism, but be at high risk of autism, and then get an environmental hit after birth that triggers it? That is a critical question we haven’t answered.

Me: Do you think The Lancet retraction will shift parent opinion?

Dr. Evdokia Anagnostou: For people like Jenny McCarthy, I doubt it. The theory has become so engrained. It’s a cause, and they feel they’re changing the next generation.

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2 comments:

It is sad that people will listen to a former playboy playmate named Jenny McCarthy!!
My youngest daughter has Autism and for years I had to answer the "vaccine" question. "Do you think the vaccine you opted to give your daughter caused her Autism?"
My response, "No I do not......are you finished judging me?"
Michelle

Good for you Michelle! It's amazing what people feel entitled to asking. It reminded me of this piece from the Globe last week -- it's all about a mom whose son has Down syndrome and how parents feel entitled to ask why she didn't have prenatal testing. What a sad culture we seem to be devolving into.

http://www.theglobeandmail.com/life/facts-and-arguments/theres-no-such-thing-as-the-perfect-child/article1470176/