The debate over vaccines and autism
Perhaps the most difficult news for parents to hear is that their child suffers from some type of disability or abnormal developmental condition. In recent years, some parents of autistic children have insisted with certainty that vaccines, specifically the MMR (Measles-Mumps-Rubella) vaccine, played a role in their child's development of autism. Despite parental clamors for additional investigation into potential links, respected scientific experiments have identified no reason to believe that any vaccination contributes to the development of autism.
A modern increase in diagnoses of autism
According to an article from the Journal of Immunotoxicology, diagnoses of children with autism have been dramatically increasing. In 1943, autism was estimated to occur in four to five of 10,000 children. Today, those numbers have grown to one in 110 in the United States and one in 64 in the United Kingdom. A report following the changing ideas about autism and immunizations from the Clinical Infectious Diseases journal says that the increasing number is probably due in part to more descriptive definitions of what constitutes autism, as well as increased awareness. In other words, even though the diagnoses for autism are increasing, that doesn't necessarily mean that the disease itself is becoming significantly more common. However, the sheer magnitude of the increase leads some to doubt that the rise in numbers is merely a result of more correct diagnoses. One hypothesis for the rising instances of autism blames the growing number of immunizations that children receive.
Early research linking autism to vaccinations
The belief in an autism-immunization link was fueled by a study in the late '90s by British Dr. Andrew Wakefield. Wakefield's study claimed to link the MMR vaccine to cases of autism in some British children. Though the report has since been declared fraudulent, the momentum from the study was propelled by the anecdotal evidence of parents who believed they had witnessed detrimental changes in their children as a result of vaccinations.
Research denying the link between autism and vaccinations
Despite parental beliefs, researchers addressing the vaccination-autism link remained adamant in their assertions that there was no identifiable link between immunization and autism. In 2004, research from the Institute of Medicine (IOM) concluded that the evidence "favors rejection of a causal relationship between the MMR vaccine and autism" and also rejected a causal relationship between autism and vaccines containing thimerosal. The report Clinical Infectious Diseases journal report cited 13 additional studies that found no link between autism and the MMR vaccine and seven additional studies that failed to show a link between autism and thimerosal.
An article from the Huffington Post explains that "regression [of autism] usually occurs between 12 and 24 months." In other words, natural regression of autism occurs at a time when many children are receiving early vaccinations, which can make it appear as though the vaccinations have caused a change, even if they were not the actual source of the change. Such misinterpretations are one reason anecdotal evidence is not considered scientifically sound.
Recent evidence revives the possibility of a potential vaccination-autism link
While anecdotal evidence is not enough to lend support to the theorized link between autism and immunizations, new evidence lends some credence to the concern. The report from the Journal of Immunotoxicology examines possible causes of autism. It lists "encephalitis following vaccination" among those possible causes. It should be noted, however, that this notation does not prove that vaccinations cause autism. It suggests that, in some cases, a specific reaction to immunizations may be a contributing factor of autism in certain individuals. The report did not mention how prevalent encephalitis is following vaccination. Clearly, more research is necessary before any concrete conclusions can be drawn.
