The puzzle that is the cause of Autism is one of the internet s favorite conundrums. In fact a google search into what causes autism will turn up 120 million hits. Glyphosate is a popular choice amongst the pseudoscience elite, so are GMOs, vaccines, high fructose corn syrup and antibiotics (yet they strangely never mention the strong correlation between the increase in autism and the increase in organic food sales). More reliable sources have attempted to link the increase in autism to gestational diabetes, induced/augmented labor, pesticides and pollution. In fact, a 2012 report cited that a billion dollars was spent between 2002-2012 to find the cause of autism.
The rise of the autism epidemic, which the CDC states is characterized by a 30 percent increase in just the last few years alone, is one of the most talked about public health issues among both scientists and pseudoscientists alike. But what if the conversation is moot? The rise might not be a change in autism prevalence but a change in the way we talk about autism.
One change is that historically autism was a neurological, developmental disorder unto itself, but in the early 1990s it changed to a spectrum of disorders (Autism Spectrum disorder or ASD). This change brought with it an expanding list of symptoms and a more subtle classifications of autistic behaviors, which led to more types of behavioral profiles being classified as autistic. Another change in the way we talk about autism is the classification that as an epidemic which brings with it a connotation that there is a single, possibly environmental cause. Referring to autism as an epidemic leads one to think of it in the same class of diseases as Malaria: if we can stop the Plasmodium parasite, we can stop the spread of Malaria, becomes if we can stop GMOs, pollution, induced labor or whatever we can stop the spread of autism.
The idea that the autism epidemic is an epiphenomenon rather than a real one is not new, but now it has data from two recent studies to back it up. The most recent study conducted in Sweden and published in the British Medical Journal examined a large volume of data from both a twin study and the Swedish national patient registry and compared autism phenotypes vs. autism diagnoses over a ten year period. They found that although the number of ASD diagnoses increased over that period, the number of people with actual autism phenotypes remained stable.
A similar study in Denmark from earlier this year, published in JAMA Pediatrics, found that more than 60 percent of the increase of ASD diagnoses can be attributed to reporting practices and not actual increases in patients with ASD. Taken together, these two two studies suggest that autism rates, either defined as classical autism or ASD, have probably remained unchanged despite what you may see on your facebook or twitter feed.
The focus we as a society give to autism is great because it truly is a debilitating disorder; however, our energy and efforts are misplaced as we are spending too much time looking for causes in all the wrong places. My hope is that these two studies can refocus researchers away from the epidemic discussion, which leads us towards looking for environmental causes, and instead use that billion dollars towards finding the real cause or causes of ASD, the most likely of which are genetic.