In Search of the Cause of Autism
How about television?
By Gregg Easterbrook
Posted Tuesday, Sept. 5, 2006, at 3:57 PM ET
Autism in the United States has been increasing for two and a half decades, from one child in 10,000 to one in 500 or perhaps even one in 166 today. Maybe advancing parental age is a factor; this Israeli study, published Monday, shows that men over 40 are more likely to father autistic children than men under 30. And it's clear that part of the rise can be attributed to better identification by doctors, improved parental candor, and, especially, an expanded definition of the psychiatric diagnosis for the ailment. But because the autism surge began around the year 1980, researchers and parents of afflicted children continue to ask what kind of exposure could have begun at that time that might account for the surge.
More ...
http://www.slate.com/id/2149002/
TV Really Might Cause Autism
A Slate exclusive: findings from a new Cornell study.
By Gregg Easterbrook
Posted Monday, Oct. 16, 2006, at 6:52 AM ET
Last month, I speculated in Slate that the mounting incidence of childhood autism may be related to increased television viewing among the very young. The autism rise began around 1980, about the same time cable television and VCRs became common, allowing children to watch television aimed at them any time. Since the brain is organizing during the first years of life and since human beings evolved responding to three-dimensional stimuli, I wondered if exposing toddlers to lots of colorful two-dimensional stimulation could be harmful to brain development. This was sheer speculation, since I knew of no researchers pursuing the question.
Today, Cornell University researchers are reporting what appears to be a statistically significant relationship between autism rates and television watching by children under the age of 3. The researchers studied autism incidence in California, Oregon, Pennsylvania, and Washington state. They found that as cable television became common in California and Pennsylvania beginning around 1980, childhood autism rose more in the counties that had cable than in the counties that did not. They further found that in all the Western states, the more time toddlers spent in front of the television, the more likely they were to exhibit symptoms of autism disorders.
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http://www.slate.com/id/2151538
TV causes autism? I doubt it.
By Steven D. Levitt
October 17, 2006
An article in Slate yesterday argued that TV watching causes autism. The Slate article is based on research done by Cornell economists Michael Waldman, Sean Nicholson, and Nodir Adilov. You can download the academic working paper here.
The paper gives some theories why TV and autism might be linked, but the more interesting part of the paper is the data analysis. The researchers are trying to find a “natural experiment” that shifts around TV watching, but otherwise has no impact on whether a child is diagnosed as autistic. Rainfall is one of the things they use. In places where it rains a lot, kids watch more TV. Maybe rainfall doesn’t affect autism in any other way. This is a creative approach, although it suffers from the weakness (which they acknowledge in the paper), that rainfall changes other things, like how much time you spend indoors doing other things besides watching TV. They also use the arrival of cable TV in an area. This approach is potentially stronger, although it would be better if they used availability of cable TV, rather than the number of people who actually subscribe.
These are intriguing approaches, but personally I did not find the empirical evidence in the paper very compelling.
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http://freakonomics.blogs.nytimes.com/2006/10/17/tv-causes-autism-i-doubt-it/
Does watching TV cause autism?
William M. Briggs, Statistician
I have no idea, but two gentlemen from the Johnson School of Management at Cornell and one from the Economics department at Purdue seem to think so. They have written a paper, which has found interest at Slate, which they boast as an “exclusive.”
Waldman’s (and others) paper, which is a couple of years old, is a prime example of how to get carried away with an idea, so it is worthwhile to review it. It’s best to download the paper so you can follow along (the paper is freely available).
The genesis of the idea was noticing that autism rates at birth in the state of California started to increase in the early 1970s, picking up pace until 2000, when their data stops (see their Figure 1). It is true to say that something caused this increase. But what?
There is no way to know, but we can posit causes and then test them. The best way to do that is by direct measurement: Propose a cause, design an experiment or collect data in which the cause was controlled and the effect happened. That is difficult to do in the case of autism, of course, since you won’t know a child is inflicted for some time after his birth. But, of course, it would not be ethical to let a cause stay in place if you suspected it would lead to autism. It is also not clear when the cause, or causes, whatever they might be, have to manifest themselves. That is, the same cause might be in place for two children, but miss its timing, so to speak, in the first case and get it right in the second. A plausible biological mechanism for the cause that fits in with other known medical science must also be in place. In short, this kind of investigation is not impossible, but it is difficult and must proceed by, if I can use the pun, baby steps.
More ...
http://wmbriggs.com/blog/2008/07/
Autism Vox blog
http://www.autismvox.com/
