We need a better explanation for the surge in autism


As we learn more about the link between genetics and the functioning of the brain, it could lead us closer to a theory to explain the increase in autism cases. (Allen Institute for Brain Science/Reuters)

The latest numbers from the Center for Disease Control showing a steep rise in the number of children with autism are so off the charts that it’s hard not to come to one of two conclusions: There’s something wrong in the way that we measure the data or there’s something extraordinary going on. 1 in 68 American children now has autism, up from 1 in 88 children just two years ago, an increase of 30 percent. A decade ago, one in 166 children were diagnosed as having autism. In 1975, it was 1 in 5000. Plot this as a graph using CDC data and you get a hockey stick curve showing exponential growth in autism over just the past decade.

If you accept the first conclusion – that we’re simply not measuring autism correctly – there’s actually a fair amount of evidence to suggest that as much as 53 percent of the variation in data can be explained away by factors such as better diagnosis, better detection and better awareness. And it’s true that the very definition of “autism” continues to change to include a much wider description of symptoms along a spectrum, so it’s only natural to expect an increase in the number of cases if we’re making it easier to define people as having autism. There’s even a growing consensus in the scientific community that the current numbers are “no cause for alarm” and may actually underestimate the incidence of autism in the population, due to problems in collecting information in more rural areas and among some demographic groups. 

That still leaves approximately 50 percent of the rise in autism cases to explain through science.

It won’t be easy. There may be as many as 60 different disorders that are associated with autism, and a multitude of factors at work, with most of them thought to be linked to changes in our environment or genetic factors resulting from increasing parental age. As a result, even the Chief Science Officer at Autism Speaks concedes that what causes autism remains a mystery. And that’s compounded by the fact that, unlike other medical disorders, there’s no definitive way to test for autism. You can’t take a blood test. You can’t take a biopsy of the skin. In fact, only 10 percent of autism cases are “definitive.”

Thankfully, science is riding to the rescue. We know more about the human genome than ever before and we are on the cusp of understanding the workings of the human brain, thanks to new brain science initiatives. Put these two areas of science together, and we might be able to solve the mystery of autism. Instead of coming up with conspiracy theories of how changes in the environment are leading to autism – they’re putting mercury in our food supplies! – science will help us focus our energy on real answers to an important question.

The latest example of how innovations in genetics and brain science can help to unravel the mystery of autism comes from the BrainSpan Atlas project. As recently reported by Natureit might be possible to track the genetic markers responsible for autism and see how they are expressed in the brain. This could lead to a breakthrough in understanding the genetic origins of autism. What’s even more exciting is that the results from the BrainSpan Atlas project will be made freely available to both the public and researchers, meaning that we’ll soon all have a “brain map” as a road map for understanding autism.

Once we understand the link between genetics and the brain, the next step is to develop a theory that can account for the stunning rise in autism in our generation. One provocative and counterintuitive theory is that autism might be explained by rapid evolutionary changes to the human brain. Through neuroscience, we know that the human brain shows signs of amazing neuroplasticity (i.e. it changes in response to external stimuli). It makes sense, then, that the human brain might be one of the first places we would see the result of evolutionary changes. It’s counterintuitive, though, because it suggests that autism is not really a “medical disorder.” Instead, autism can be understood as the result of combining genetic markers for specific aspects of brain activity and human personality in unpredictable ways. 

In 2012, Juan Enriquez, a Harvard academic, futurist and venture capitalist, outlined the possible link between evolution and autism in one of the most popular TED videos of all-time (1.4 million views and counting). At a time now when the average person absorbs more information in a single day than our ancestors did in an entire lifetime, Enriquez points out, it’s not out of the realm of possibility that our brains would change in response to these external stimuli. Within a generation, those changes would conceivably start appearing in the gene pool as people mate. Over a period of several generations, those changes would begin to be observable within the general population. Which might explain why the autism numbers have spiked over the past 30 years.

Think of it this way: It’s almost as if all those “Google is making us stupid” or “online skimming and scanning is changing my brain” stories are actually coming true and expressing themselves in the human gene pool. In fact, you could build out a convincing narrative to explain the high incidence of the following autism-like traits in the population: hyper-attention, hyper-perception and hyper-memory. If you buy into the argument that the only way to deal with the modern information economy is to change our brains to account for the massive influx of data and information in our lives, then maybe nature is already doing the job for us, we just don’t realize it. 

There are obviously tradeoffs involved, however. It’s not as if nature is giving us a free ride. Evolutionary changes are not linear — it’s more like ongoing genetic experimentation, in which nature sees what works, and what doesn’t work. Over time, what works will crowd out what doesn’t work. Genetic markers for “attention” and “perception” and “memory” may be undergoing some type of mutation in the gene pool in which they are also affecting genetic markers for “personality” and “communication.” This might explain one really fascinating part of the CDC results, in which an ever-higher incidence of individuals characterized as “intelligent” are being diagnosed as having traits on the autism spectrum.

Of course, one could argue that mentioning autism and evolution in the same sentence is just about as junky as junk science gets. At best, it sounds like something you’d hear at a TED conference or something that proponents of the Singularity would embrace, but nothing that should be voiced in polite conversations involving medical experts. In some people’s minds, invoking “evolution” surely ranks right up there with the host of other explanations that have been given to explain autism – that vaccinations cause autism or that obesity during pregnancy causes autism. Given that 33 percent of Americans don’t believe in the theory of evolution, right from the get-go, you’ve lost nearly one-third of your audience with such a provocative theory.

But that’s the way it goes with science. We come up with theories, test them, and discard them if they don’t work. At times they can be provocative and even counterintuitive. We owe it to ourselves to consider every option, every theory, if there’s a chance that it can help us arrive at an answer. Behind the CDC numbers, there are millions of people and millions of families, all of them wanting to know what’s behind the dramatic surge in autism.

Dominic Basulto is a futurist and blogger based in New York City.
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