Sunday, March 09, 2008

Autism and Vaccines

The New York Times has a story on a lawsuit over vaccines and autism. It opens as follows:
Study after study has failed to show any link between vaccines and autism, but many parents of autistic children remain unconvinced. For the skeptics, the case of 9-year-old Hannah Poling shows that they have been right along.

The government has conceded that vaccines may have hurt Hannah, and it has agreed to pay her family for her care. Advocates say the settlement — reached last fall in a federal compensation court for people injured by vaccines, but disclosed only in recent days — is a long-overdue government recognition that vaccinations can cause autism.

“This decision gives people significant reason to be cautious about vaccinating their children,” John Gilmore, executive director of the group Autism United, said Friday.
The government argued that it did not cave in to anti-vaccine hysteria:

“Let me be very clear that the government has made absolutely no statement indicating that vaccines are a cause of autism,” Dr. Julie L. Gerberding, director of the Centers for Disease Control and Prevention, said Thursday. “That is a complete mischaracterization of the findings of the case and a complete mischaracterization of any of the science that we have at our disposal today.”
So, why did they settle? It's not clear from the news stories, and I don't have access to the settlement. Given the attitude toward science in our government, decision-makers may have decided not to let the facts bother them when their minds were made up. Or, maybe they just decided that they didn't want to put this one in front of a jury that might be controlled by sympathy, rather than science.

To understand the science, you have to understand some background. There are two reasons why people began worrying that vaccines may be causing an "epidemic" of autism. The first is that autism rates have been rising along with vaccination rates. The second is that symptoms of autism emerge at roughly the same time as vaccinations occur. So, it seemed like a logical hypothesis. Thimerosal quickly became the culprit.

Thimerosal is a vaccine preservative, and it contains ethylmercury in very low doses. There had been general consensus that the doses were low enough to be of no concern. However, the safety standards were based on methylmercury exposure, and it was thought remotely possible that there could be greater risk with ethlymercury. Alternative preservatives had been developed and it seemed prudent to eliminate thimerosal. Beginning in 1989 thimerosal levels were reduced in vaccines. The process was completed in 1992.

Because Thimerosal levels have been reduced over the years, a good way to track the effects of Thimerosal exposure is look at rates of autism as they correspond to Thimerosal exposure. A number of these studies (summarized here) have looked at this. Of particular interest is the California study. They looked at autism rates in California from 1989 to 1992, when Thimerosal was being removed from vaccines. Had Thimerosal increased risk of autism, rates of autism would have dropped over the course of the study. Instead, there was no change in the frequency of autism. Since they were relying on practitioner's diagnoses, there was no room for bias (by massaging diagnoses) in the study.

Hannah, the autistic girl in the lawsuit, was a member of the age group in the California study. According to the story, she got 5 immunizations at the same time, but still, she would have been getting lowered doses of Thimerosal, because she was getting them after 1989. Again, overall, Hannah's age group showed no change in it's rates of autism over the course of the study.

As an alternative to Thimerisol, there has also been concern about the measles, mumps, and rubella (MMR vaccine) itself causing autism. Here, the evidence is even weaker. Studies purporting to show a relationship usually involve smaller numbers of cases. They often rely on investigating groups of autistic children and try to relate the emergence of autism with receiving the MMR vaccine. However, as I said before, vaccination occurs at the same age that autism emerges, so you're bound to see a correlation. The only way to identify a relationship here is to examine individuals both with and without autism who have both received vaccinations.

The data just doesn't support a relationship between vaccines and autism. The best explanation for rising autism rates comes from two sources. First, there have been marked changes in diagnosis. We used to see autism as a single entity. You were either autistic or you weren't. Today, we see autism as a spectrum of disorders; you may be more or less autistic. So, people previously diagnosed as mentally retarded are now seen as autistic. High functioning autistic individuals used to be diagnosed with "childhood schizophrenia." Today they're diagnosed with Asperger's disorder, which is considered a form of autism.

Secondly, and perhaps more cynically, diagnostic labels determine access to some services. There are a large range of services for people who are called autistic. If someone's "just" mentally retarded, they may not have access to the same services. Hence, providers may say, "This kid needs Day Training Program A. If I call him 'autistic,' he'll get it. If I call him mentally retarded, he won't." I can't prove this happens, but it wouldn't surprise anyone in this business.

My first professional position after graduate school involved working in an institution for people with mental retardation. I was involved in the group of professionals who made it possible to clear the institutions and get people with cognitive and developmental disabilities living in the community. So, over the years, I've seen a lot. What I've seem mostly, is parents struggling with their disabled children.

As late as the 1960's, the conventional wisdom was to tell parents to put their cognitively disabled children in an institution and try to forget about them. Parents who followed that advice were often consumed by guilt. Today, thankfully, disabled children live and are educated in the community. But it's a terrible strain on the parents and on other family members to have a disabled person in the house. Behavior modification, the best treatment for autism, requires an incredible amount of time and effort. Even so, the guilt hasn't been completely eliminated.

Parents wonder if they caused their child's autism. Was it that drink I had when I was 3 months pregnant? Or that I smoked, or that I chose to have a child at 38? Maybe it was a toxin I was exposed to at work? Maybe I shouldn't have worked? Maybe I should have taken better care of myself?

Wouldn't it be nice if autism was caused by the doctor, and not me?

My heart goes out to parents of disabled children. Their desperation leads to all kinds of ideas; I've seen them come and go. Megavitamin therapy was big for a while. Give lots of vitamins to your autistic child and he won't be autistic any more. Didn't do a thing. Remember assisted communication? The idea was that autistic children had only impaired communication skills and if we helped them communicate they would be just fine. It turned out that the people that helped them communicate were really doing the communication themselves. It's hard to find a good reference to it now on Google.

This doesn't mean we should throw our hands up in despair. As Rabbi Tarphon, a Jewish sage remarked, "It is not required that you complete the job, but neither are you free to abstain from it." We cannot cure or prevent autism yet, but as a community we can support autistic people, their families and other caregivers. We cannot give support by pretending there is an easy cure or an easy explanation for their children's illness.


Therapy said...

All these responses basically come from the extreme stress and fatigue parents of special children face. Trying to look for a solution is one way of keeping the long reality at bay

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