Dr. Dustin Ballard: Don't blame autism on shots
Before you rush out to stock up on pints of Cold Stone Creamery and shares of Ben & Jerry's, I should mention that people eat more ice cream in the summer. They are also more active and have higher metabolic rates in warmer weather. So, perhaps it's not the ice cream that leads to weight loss but rather seasonal variation in calorie burning. What's the lesson here? That causality can be elusive.
Causality, for those not familiar with the term, simply means "cause and effect." Determining whether there is genuine causality between two entities, rather than a chance association or one unduly influenced by unrecognized factors (called confounders), is difficult. For example, many people still believe that exposure to cold weather causes pneumonia. But it's actually not the chilly weather that increases the risk of pneumonia, it's that during the cold winter months people stay inside and are in closer contact with other people's germs. Proving a clear-cut link between a dietary item, personal habit or medical treatment and a disease process is fraught with the potential for misinterpretation.
Consider the proposed connection between routine childhood vaccinations and autism. The diagnosis of childhood autism is on the rise and we don't know why. Since the 1990s, autism rates have increased by 700 percent to 800 percent.
As a parent, I have experienced a good deal of anxiety about the possibility that the routine measles-mumps-rubella (MMR) vaccine and/or a mercury-based additive (thimerosal) once used in children's vaccines could be responsible for the incredible spike in autism- especially since this spike has hit close to home.
I have a niece and nephew who have each been diagnosed with an autism spectrum disorder and my wife has repeatedly agonized about the immunization process for our own children. But as a medical professional, I have unabashedly preached that routine immunization programs are critically important for the public's health. After all, vaccination efforts have a proven track record: they eradicated smallpox and made polio a disease only seen in paranoid communities (such as the Nigerian province that banned immunizations because they believed they were a Western plot to sterilize their children.) Thus, when I was confronted with the possibility that routine shots could permanently alter the neurochemistry of my children, my friends' children, or anyone's children, I was frightened. Even more so because the alternative to community vaccination is a free-for-all of childhood diseases and, as in Nigeria, the widespread return of a horrible illness like polio.
Fortunately, my fears have been allayed by the alignment of an overwhelming preponderance of medical research against the vaccines-cause-autism hypothesis. Last month, a federal court considering this question ruled in favor of the U.S. government, clearing immunizations of causality. Special Master George L. Hastings Jr., after reviewing 5,000 pages of testimony, concluded that the government's expert witnesses were "far better qualified, far more experienced and far more persuasive" than those of the plaintiffs.
Additionally, a California Department of Health study released last year found that autism rates in the state rose continuously from 1995 through 2007, despite the fact that thimerosal was removed from all vaccines (except some flu shots) in 2001. Since signs of autism usually surface by age 3, one would expect that if thimerosal in vaccines was the problem, the autism diagnosis rates would have dropped between 2004 and 2007. They did not. This simple finding, which is supported by a number of other rigorous investigations, is compelling evidence that researchers will have to look elsewhere for the cause of the autism epidemic.
In contrast, the primary scientific evidence supporting a link between vaccines and autism is a small study published in the medical journal Lancet in 1998 - a study that has been thoroughly discredited. Since its publication, it has come to light that there was a conflict of interest (the research was secretly funded by plaintiff lawyers) and that the data was falsified. Its findings (linking intestinal inflammation with the MMR immunization and subsequent autism) have not been replicated in larger studies and have been repudiated by 10 of the paper's 13 authors.
Why, with all of this evidence, is there a persistent perception that vaccines cause autism? It's kind of like ice cream and weight loss in the summertime. People eat ice cream during the time of year when they are most likely to lose weight. Children are diagnosed with autism at around the same time as they receive vaccinations. Virtually every child who has autism will have also been immunized, and in some rare cases, children with underlying immune or metabolic disorders may have their inevitable symptoms unmasked by vaccination. Thus it is easy to stray down the path to mistaken association.
But, if it's not the shots, what is it?
That's tricky, too. There are other suspects; genes, environmental toxins and television have been implicated. But it seems that a significant culprit is increased awareness among parents and physicians of the behavioral and cognitive manifestations of autism. With increased awareness comes increased recognition and diagnosis.
Still, no matter how persuasive the evidence proving otherwise, some people will remain fixated on vaccines as the agents of autism. This is unfortunate and shortsighted. Failure to vaccinate children can have real and deadly consequences. There are many parents out there who might say. "Well, my child didn't get vaccinated, and she didn't get sick." Those parents should know that is the reason their child didn't become ill is because the vast majority of the other kids in their community did get vaccinated. But if enough of those other children don't get vaccinated, more children will get sick.
So, it is time to turn our attention to other possible causes and treatments for autism and leave the vaccines alone. No medical treatment is completely risk-free, but routine childhood immunizations are clear winners in any cost-benefit analysis. Despite its indisputable deliciousness, the same cannot be said of ice cream.
For more information about the importance of this issue in Marin County, contact Dr. Clark Hinderleider of the Health Council of Marin at: CLARKMDPH@aol.com
Dr. Dustin W. Ballard is an emergency physician at Kaiser Permanente San Rafael and the author of "The Bullet's Yaw: Reflections on Violence, Healing and an Unforgettable Stranger." His Medically Clear column appears every other Monday.
