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Big Think hosted a panel discussion highlighting cutting-edge autism research as part of our Breakthroughs series, made possible by Pfizer. This conversation features back-and-forth exchanges between top luminaries in the[…]

Many kids are vaccinated at age two, the same age at which autism is often first noticed. But the “evidence” that one causes the other doesn’t wash.

Why Vaccines Don’t Cause Autism

Wilczynski: In the last decade there has been a great deal of public controversy surrounding the idea that vaccines might cause autism.  Where did this perception come from and tell us do you think it’s wrong and why?

Fischbach:  How much time do we have?  I can trace the origins of that idea and you’ll see right at the end that it’s always difficult, if not impossible, to say a concept like that is wrong.  You can say that it’s unlikely or that it’s not among the prominent hypotheses today.  It came... the origin I believe came from a study in England of an individual, a physician at the Royal Free Hospital who were studying children who had infections, viral infections.  It seemed to disrupt their bowel habits. And he postulated that there were toxins being released from the bowel.  In fact, many children come to autism clinics early on with GI/bowel disturbances. But he pointed to vaccines as causing this, that somehow it disrupted normal bodily function and caused release of toxic materials that affected the nervous system and that led to widespread suspicion. 

There is a phenomenon...  It is not all that common, but there is a phenomenon where autism could get worse at about age two.  There are some controversies whether regression is a prominent part of autism, but many people feel that it’s very hard to diagnose autism before you can begin really talking in detail with a child. But there is some hint that some children develop normally up to age two and then go through a precipitous decline—and that is about the time they receive the measles, mumps and pertussis vaccine.

So you have two very common things, autism, 1 in 110 children some people estimate, and vaccination. And the correspondence was almost too much to ignore, especially with a troubled family looking for reasons and so the suspicion grew and then some epidemiologic studies were suggestive, but the great, great majority and millions of dollars have been spent on epidemiologic studies, have found no correspondence between vaccination and autism.  It doesn’t rule it out.  Nothing will rule it out until we know what the cause is.

One aspect of it that has been ruled out I believe is a preservative in the vaccine, the ethyl mercury and the mercury is put in vaccines so that the vial can be used over and over again, especially in general clinics where you have to vaccinate several children and it was thought that mercury was triggering autism and in fact, many children were treated with agents to remove mercury and other heavy metals from their system, very toxic drugs. But mercury has been removed from the vaccines since 1987.  There is really... first reduced to very low levels and now essentially eliminated and the autism reported prevalence is still... hasn’t decreased.  If anything, it is on the rise. 

I believe the reported prevalence, and everybody should chip in, is due to wider recognition, broadening of the criteria... and you can trace this in the diagnostic and statistical manual of the American Psychiatric Association. The criteria got broader and broader and broader and more people were recognizing that their children had a slight disability.  Resources became available for helping families and stigma, although it’s not gone by any means, is slightly reduced, so I think, I believe the prevalence was just as high 20 years ago, just not recognized.  I don’t believe there is something that's happened in the environment, but other people...

Wilczynski:  I would add to that our diagnostic tools have become much better during that period of time.  Historically the professional who was providing a diagnosis relied almost exclusively on behavioral observation that wasn’t necessarily highly structured or standardized and now we have more structured interviews.  We have more structured observations. And people are very careful to collect data, as you mentioned earlier, from school professionals, from parents, as well as engaging with the child themselves. And so more professionals have been educated about how to diagnose individuals and the tools we use are actually much better. 

Fischbach:  Absolutely right.  There is a postscript to this.  The original paper was written by a physician written named Andrew Wakefield, who has been debarred in England.  The paper has been withdrawn.  I think something like eight out of the nine authors have withdrawn their names and it’s thought to be totally fabricated, so it was based on a sham and it has not been supported and the reason I'm rather vehement about this is the danger in not vaccinating children is real.

Bookheimer:  I would like to add to that.  In Los Angeles Country where I live 10 children died of pertussis last year, which would normally be... would never happened.  It’s unprecedented and it’s because parents are not vaccinating their children and they’re passing germs and diseases around that weren’t being passed around before and that is a direct consequence of this.