Has Incidence of Autism Increased?
Recently a report from the CDC's Autism and Developmental Disabilities Monitoring (ADDM) Network indicated that the prevalence of autism spectrum disorders (ASDs) amongst 8-year-old children had increased from 6.7 per thousand children in the year 2000 to 11.3 children per thousand children in 2008. That means that in year 2000, one in 150 children was diagnosed with ASD and in 2008 it was one in 88 children. The question is why has the incidence increased so steadily? None of us medical professionals currently know, but most believe the majority of the increase is due to our greater awareness of the diagnosis and improved record keeping. There are likely many factors that account for the increase in incidence of recorded ASD and researchers continue to search for exposure or risk factors. However, there are a number of established risk factors for developing an ASD and these include genetic and non-genetic associations including:
- Sibling or parent with an ASD
- Children born to older parents
- Certain genetic disorders (Down syndrome, Fragile X, tuberous sclerosis, and others)
- Certain drugs (thalidomide and valproic acid)
- Low birth-weight, prematurity
One of the major challenges of ASDs is that they can neither be simply categorized nor described. They exhibit a “spectrum” of symptoms and severities involving a variety of typical social, communication, and repetitive behaviors.
Is There a Link Between Autism and Vaccines?
There is no documented link between vaccines and autism. Illnesses that can be prevented by vaccines are much worse than any risk from the vaccines developed to prevent them. Moreover, that there was no evidence that vaccines are linked to autism. The primary study “linking” immunization with the MMR vaccine and thimerosal with autism was withdrawn due to falsification of data, and since then there have been a number of studies that have verified the lack of an association between MMR and ASDs. It is very important to remember that despite the fact that no new vaccine licensed by the FDA for use in children has contained thimerosal as a preservative since 2001, the number of children diagnosed with autism has almost doubled. It seems clear that thimerosal and vaccines are not the culprits.
Unfortunately, anti-vaccine groups continue to demonize the practice and are promoting concepts that are putting children at risk. Herd immunity occurs when the majority of individuals are immunized. Individuals who decide not to immunize their children put that herd immunity at risk, and are dependent upon the vaccine status of the rest of our children. The problem is that at some point herd immunity wanes and then those old diseases arise again. As a result, measles cases are on the rise and other vaccine-preventable illnesses are starting to show up after years of lying dormant.
There is some promising news in all of this. ASDs are on the rise, but a recent study from Columbia University indicates that that early intervention can result in rapid gains in function in certain groups of children diagnosed with severe symptoms. A major difficulty is that the ASDs are variable in symptom severity and research is still being done to determine which intervention or therapy would best serve which patients.
Are Reduced Vaccination Rates Responsible of Increases in Deadly, Preventable Disease?
In 2000, measles was declared eliminated from the United States. According to the CDC's MMWR (Morbidity and Mortality Weekly Report) from May 27, 2011, “from 2001 to 2008, a median of 56 measles cases were reported to the CDC and during the first 19 weeks of 2011, 118 cases of measles were reported, the highest number reported for this period since 1996.” The report continued to identify that the majority of those hospitalized were children less than 5 years old and unvaccinated. Fortunately, there were no deaths.
Measles is only one example. Vaccination programs against other diseases have similar stories all resulting in dramatic decreases in morbidity and mortality, especially in children. These include:
Studies thus far have not revealed any relationship between vaccines and autism. Nevertheless, this doesn't mean that the research should completely stop. Significant research and development in the field of vaccinations needs to continue for the foreseeable future, so that we can one day hope to decrease the number of deaths and hospitalizations due to preventable infections.
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Centers for Disease Control and Prevention (CDC). "Community Report From the Autism and Developmental Disabilities Monitoring (ADDM) Network. Prevalence of Autism Spectrum Disorders (ASDs) Among Multiple Areas of the United States in 2008." Autism and Developmental Disabilities Monitoring Network 2012. <http://www.cdc.gov/ncbddd/autism/documents/ADDM-2012-Community-Report.pdf>.
Centers for Disease Control and Prevention (CDC). "Summary of notifiable diseases—United States, 2009." Morbidity and Mortality Weekly Report 58.53 (2011).
Fountain, Christine, et al. "Six Developmental Trajectories Characterize Children With Autism." Pediatrics published online April 2, 2012. <http://pediatrics.aappublications.org/content/early/2012/03/28/peds.2011-1601>.
Mrozek-Budzyn, Dorota, et al. "Lack of association between measles-mumps-rubella vaccination and autism in children: a case-control study." The Pediatric Infectious Disease Journal 29.5 (2010): 397-400.