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Is Autism Spectrum Disorder Becoming More Prevalent?

With the Centers for Disease Control and Prevention reporting that the number of children in the United States with a diagnosed autism spectrum disorder rose substantially between the years 2000 and 2010, parents, doctors and researchers alike are wondering whether there has been an actual increase in the prevalence of the disorder. There is no clear-cut answer to this question, although experts mostly agree that some—but likely not all—of the increase in diagnosis stems from heightened awareness and broader diagnostic criteria.

The Numbers

In 2000 and 2002, CDC data indicated that approximately one in every 150 U.S. children had a verifiable autism spectrum disorder. This number began to increase every two years after 2002 with approximately one in every 68 children having a diagnosis by 2010, marking a 120 percent increase in cases. Only one in every about 2,000 children received a diagnosis of an autism spectrum disorder during the 1970s and 1980s, reports WebMD.

Boys are significantly more likely than girls to be on the autism spectrum, with one in every 42 boys compared to one in every 189 girls having a diagnosis.

Diagnostic Criteria and Substitution

It is indisputable that the prevalence of actual diagnosed cases of autism spectrum disorders has increased dramatically over the years. However, scientific researchers point out that this may not be entirely due to environmental or genetic factors. For example, as WebMD states, changes in diagnostic criteria in the Diagnostic and Statistical Manual of Mental Disorders have made it more common for children with milder cases of autism to receive diagnoses. Children with the same symptoms existed in previous years, but they were not included in statistical data because doctors did not recognize them as having an autism spectrum disorder.

Another factor that likely plays a role in the increase in diagnosis is the phenomenon of diagnostic substitution. Schools may recognize children who received labels such as “mental retardation” a few decades ago as being on the autism spectrum today. Part of the reason for this is that the education system did not include autism as a special education category until the early 1990s.

Genetic and Environmental Contributors

Investigating the genetic and environmental causes of autism is the key to determining exactly how much more prevalent autism disorders are becoming, if at all. According to a study published in June 2015, the risk of autism spectrum disorders rises with higher maternal or paternal age. It is, therefore, possible that autism has grown more prevalent due to people delaying parenthood at increasing rates, although more research is necessary.

An example of a genetic factor to which research shows a potential link to autism is maternal exposure to pesticides while pregnant. Environmental exposure to certain types of polychlorinated biphenyls, which are chemical compounds that are known developmental neurotoxins, may also contribute to the development of autism spectrum disorders.

Whatever the case, additional scientific research is necessary to determine whether genetic and environmental contributors to autism have themselves grown more prevalent over the years. And whether or not autism spectrum disorders are truly becoming more prevalent as time passes, an increased number of diagnoses has definitely increased public awareness—something that is undoubtedly wonderful.

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