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And Babies Don't Come From Storks, Either

Science: The alleged link between vaccines and autism is just the latest example of finding causation out of coincidence.

May 07, 2000|CAROL TAVRIS | Carol Tavris is a social psychologist who writes on behavioral research

So which is it? Is autism a result of routine vaccinations or, as a new study suggests, is it a genetic disorder diagnosable in blood proteins at birth?

In a recent letter to The Times, a mother of an autistic daughter thinks it's vaccines, though that means blaming herself. "I cry every time I think of the days and trips to doctors' offices in which they told me those vaccinations were to protect my daughter," she wrote. "Instead, I helped them to give my daughter autism . . . Damn those creators of dream-killers . . . I damn them for my marriage and myself."

Where have we heard this tragic but misguided self-blame before? For decades, Bruno Bettelheim persuaded the public that autism was caused by cold, rejecting, "refrigerator" mothers. Countless mothers berated themselves for causing their children's autism. Bettelheim was no scientist, but a self-proclaimed "expert" who based his ideas on his own subjective, selective perceptions of a few children in his school.

Years later, when proper studies were done--using objective tests and comparing autistic children and their parents with control groups--scientists found that parents in both groups did not differ psychologically. Researchers discovered that autism is a biological disorder not caused by parents' behavior.

Yet, when one Bettelheim falls, others take his place. Some influential people in the autism world, for example, endorse megadoses of vitamin B6 and magnesium as treatments (there's no sound evidence that they help); assure parents that vitamin megadoses have no negative side effects (they are toxic and can produce irreversible damage to the central nervous system); and encourage parents to defy the "authorities" and experiment with treatments. Their latest pseudoscientific mischief is to blame vaccines.

The appeal of the vaccine explanation reflects the universal human inclination to confuse correlation with causation: The fact that two events are linked in some way must mean that one causes the other. When the two events are especially vivid, the chances of creating what social scientists call an "illusory correlation" increase. For example, the number of storks nesting in some European villages apparently correlates with the number of human births there. If you know when the storks will nest, you can predict when more human births than usual will occur. Does that means that babies attract storks? Unlikely. Human births are more frequent at certain times, for reasons that are fun to imagine, and the peaks just happen to coincide with the storks' nesting periods.

Many of the children who are diagnosed with autism also get the MMR vaccine (for measles, mumps and rubella) at about the same time. This is a coincidence. Nonetheless, when emotional vulnerability meets scientific illiteracy, panic is likely to ensue.

The vaccine alarmists also reason that because the number of vaccines and the incidence of autism have both increased, the first must be responsible for the second. But there is no scientific evidence that we are in the midst of an autism "epidemic." According to Gina Green, director of research at the New England Center for Children and a specialist in the behavioral treatment of children with autism, more children are being diagnosed as autistic today because of changes in diagnostic and reporting practices. The criteria for diagnosing autism were broadened a few years ago. Many children and adults now are being diagnosed as falling somewhere on an autism "spectrum," where once they would have been given some other label--or no diagnosis. Children also are being labeled autistic at much younger ages.

The other reason people are panicking, Green believes, comes from a report from one of the state Department of Developmental Services-funded regional centers, claiming a huge increase in autism in that office's area. But this report was not a scientific study. It was a summary of the number of children who had been labeled autistic by the school districts reporting to the center. "To my knowledge," says Green, "those diagnoses were not verified by qualified independent evaluators. Autism is not easy to diagnose accurately, and is often misdiagnosed by public school personnel."

At a National Academy of Sciences conference last December, Dr. Eric Fombonne of Britain carefully analyzed the few sound studies that have been done and showed that apparent increases in autism can be accounted for by the expanded diagnostic categories and by new reporting practices.

Scientific research thus has contributed immensely to debunking incorrect ideas about autism. The news of finding a possible biological marker of autism is exciting, but the study has not been replicated, or even published in a peer-reviewed scientific journal. We will have to wait and see.

Many parents of autistic children are tired of waiting, and this makes them vulnerable to the assertions of the nonscientists and quacks who feed their alarm and who, more dangerously, encourage them to abandon proven procedures in favor of unvalidated ones. The mother who wrote the afore-mentioned letter, for example, is quick to blame scientists for requiring vaccines, but not the "experts" who promote unsupported beliefs and cures.

The alleged link between vaccines and autism is this year's illusory correlation. In a culture eager for simple explanations, unfamiliar with how scientific research works and impatient with its contradictions and pace, there will be others. Even when it cannot provide "the" answers, science teaches us to examine evidence and ask critical questions. Do we have a biological marker for autism? Not yet. Does the evidence support the letter-writer's belief that by vaccinating her daughter, she ruined her child's mind? That's a no-brainer for science. No.

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