Vaccines Cause Autism

Melissa Stone | melissa.stone@yale.edu April 24, 2010

A sizable number of parents with autistic children believe early vaccinations are the cause of their childrens’ condition. Similarly, many parents now refuse vaccinations for their children for fear of autism. Two pre­vailing ideas are that : 1) the mercury-based preservative named thimerosal in some vaccines causes autism, and 2) the measles, pumps, and rubella (MMR) vaccine leads to intestinal problems that in turn instigate autism development.

However, numerous investigations have failed to provide substantial evidence for either hypothesis. Why, then, do so many people still believe that vaccinations cause autism? How did this belief originate?

The erroneous belief began when British researcher Andrew Wakefield published a study in 1998 in The Lancet, linking childhood vaccines to autism. Since this publication, rates of childhood vaccinations dropped dramatically in Europe and the United States. Yet also since Wake­field’s study, more than a dozen epidemiological studies have been done throughout the world to test it, and there is little evidence to support the link. Additionally, many newspapers have since published evidence that Wakefield falsified and inappropriately manipulated his data. The American Academy of Pediatrics, the Institute of Medicine, and the World Health Organization have not found a sufficient link between autism and vaccines, and they continue to endorse the MMR vaccine.

There are several underlying factors that make childhood vac­cinations an easy scapegoat for parents of an autistic child. The Center for Disease Control and Prevention recommended in 2009 that over thirty different shots be given to all children before they are three years old. Specifically, doctors recommend the MMR vaccination to be given at eighteen months, which is a common time for a child to show signs of autism.

Autism is a neurodevelopmental disorder characterized by impaired social interaction and communication. At two months, most children notice major events, but autistic children tend to focus on the less salient details of their surroundings. At eighteen months, when a child is typically given the MMR vaccine, most children can speak a few words and are able to understand simple instructions. Many autistic children, on the other hand, show language delays. This would understandably raise concerns for a parent. Furthermore, autism appears to many as an“unnatural” disorder, similar to how vaccines are an “unnatural” means of preventing disease. Although a person with autism might appear healthy and look just like those with normal cognitive function, the autistic person acts atypically, such as avoiding prolonged eye contact and engaging in repetitive behaviors. Those with autism are also “unusual” in that many exhibit a great spread between their verbal and nonverbal IQ scores. Some are even considered autistic savants, displaying an expertise in a particular area, such as being able to tell you the day of the week on a particular date ten thousand years ago within seconds.

In addition to unusual traits, autism is also characterized by an unusual developmental trajectory. We tend to think of diseases as developing slowly. While most autistic children indeed show signs of autism from an early age that develop over time, some autistic children start out seemingly normal and then regress. This drastic and sudden change is the child’s behavior often occurs when the child is less than four years old. The unnaturalness of autism leads many parents to believe that something unnatural was the cause – and vaccinations, as manu­factured means to manipulate normal bodily conditions, fit the bill.

Technology, with its easy access to large amounts of informa­tion, has further perpetuated the myth that vaccines cause autism. There are many online forums and websites designed for parents of autistic children, some of which foster the spread and the prevalence of misunderstood theories and ideas about autism. For example, parents can read the blog “MomLogic,” in which Holly Peete discusses life with an autistic child. She writes, “I firmly believe that [the vaccinations] took my son to a place of no return and his body could not handle it.” Alternatively, parents can turn on their televisions to see Jenny McCarthy, an activist for removing the “toxins” from vaccinations that she believes cause autism, share her beliefs on Larry King Live, Oprah, or The View.

But if vaccines do not cause autism, then what does? Scientists have yet to find a single cause for autism, and many believe that the disorder is caused by a combination of genetic and environmental factors, including the environment of the womb, that lead to certain changes in brain structure. Autism might even be exacerbated by previously existing immune deficiency or food allergies. Vaccines, however, are not within the list of potential causes.