Here’s something that most reasonable people can agree on: Vaccines don’t cause autism. And yet, when your Facebook friends decide that it’s time to go on another crusade against BIG PHARMA, one of their main talking points is often the fact that autism rates continue to climb and why is that if not for the insidious effects of all those chemicals injected right into a baby’s body? That image will definitely win some converts, the reality is much different, and autism rates are climbing for much less shareable reasons.
While autism has probably been present throughout history, the definition of the disorder, Scientific American reports, has changed drastically since it was coined as ‘infantile autism’ in 1943. Between then and 1980, when autism finally made it into the Diagnostic and Statistical Manual for Disorders (DSM), the criteria for diagnosis was revised and expanded, and it continued to shift between different editions of the DSM. The latest edition of the text, for instance, removed Asperger’s Syndrome from its pages. Then there’s the fact that in 1991, the Department of Education decreed that children diagnosed with autism were eligible for special education. Suddenly, children who had just been listed as “intellectually disabled” before were receiving the new diagnosis and, Scientific American reports, families were becoming more encouraged to have their children diagnosed in order to get access to support in schools.
Even more interestingly, because some children may have been misdiagnosed with intellectual disability to begin with, as autism rates go up, the rates of children being diagnosed with intellectual disability are decreasing, meaning that it may not be that autism is actually becoming more common, just that it’s being diagnosed more accurately. And that also has to do with how aware the public is becoming of the disorder.
Until the 1980s, many people with autism were institutionalized, rendering them effectively invisible. Studies show that parents who are aware of autism’s presentation—by living near someone with the condition, for example—aremore likely to seek a diagnosis for their children than parents with no knowledge of the condition. Living close to urban centers and having access to good medical care also boost the likelihood of diagnosis.
Policy changes may have also played a role. In 2006, the American Academy of Pediatrics recommended screening all children for autism during routine pediatrician visits at 18 and 24 months of age. This move may have led to diagnoses for children who would otherwise have slipped under the radar.
These are just a few of the factors that are influencing the numbers. Others include how the CDC tracks autism — it’s an imperfect method and rates of the disorder vary wildly from state to state — as well as more children, particularly from minority groups, being able to access diagnostic services. And new rules allow for children diagnosed with autism to also be diagnosed with ADHD, something Scientific American reports hasn’t always been the case.
Finally, if rates are increasing, then researchers need to look at biological factors more closely. Parental age, for instance has been shown to be correlated with development of the disorder. Infants born prematurely are also at higher risk for developing the disorder.
Check out the full list of reasons here and then commit them to memory, just in case you need to explain that that whole vaccine thing to another friend who’s fallen for something Jenny McCarthy said.