« Incentives for Organ Donation | Main | Designing a statistics regime for selfish economists »
Does television viewing trigger autism?
Gregg Easterbrook says yes, citing this new study. Here is part of the abstract:
...we empirically investigate the hypothesis that early childhood television viewing serves as such a trigger [for autism]. Using the Bureau of Labor Statistics’ American Time Use Survey, we first establish that the amount of television a young child watches is positively related to the amount of precipitation in the child’s community. This suggests that, if television is a trigger for autism, then autism should be more prevalent in communities that receive substantial precipitation. We then look at county-level autism data for three states – California, Oregon, and Washington – characterized by high precipitation variability. Employing a variety of tests, we show that in each of the three states (and across all three states when pooled) there is substantial evidence that county autism rates are indeed positively related to county-wide levels of precipitation. In our final set of tests we use California and Pennsylvania data on children born between 1972 and 1989 to show, again consistent with the television as trigger hypothesis, that county autism rates are also positively related to the percentage of households that subscribe to cable television. Our precipitation tests indicate that just under forty percent of autism diagnoses in the three states studied is the result of television watching due to precipitation, while our cable tests indicate that approximately seventeen percent of the growth in autism in California and Pennsylvania during the 1970s and 1980s is due to the growth of cable television. These findings are consistent with early childhood television viewing being an important trigger for autism.
I am unconvinced. Precipitation, in these states, is a coastal phenomenon and is proxying for heterogeneity in the gene pool. Perhaps the coastal areas attract a more "autism-ready" group of individuals. In fairness to the authors, they do try to control for income and education and population density and diagnosis capacity, among other variables. Note two worrying features in the results: in California precipitation is not correlated with autism rates at all (there is a north vs. south split for rain, rather than the coast vs. inland), and precipitation is a better predictor of autism than cable viewing is directly.
Here is the latest autism news on the genetic front.
Addendum: Steve Levitt is also skeptical.
Posted by Tyler Cowen on October 17, 2006 at 07:29 AM in Science | Permalink
Comments
One of the common theories about rising levels of autism is increased pollution. The precipitation levels and cable adoption indicators both support the pollution theory. Pollutants are more common in urban areas where cable was adopted sooner, and precipitation can increase pollution by washing pollutants into groundwater, which then becomes drinking water (also by moving people indoors where pollutants tend to concentrate).
Posted by: Norm Suchar at Oct 17, 2006 7:55:32 AM
The precipitation angle also calls to mind the role of vitamin D in brain development. Maybe the kids just aren't getting enough sunlight...
Posted by: bbartlog at Oct 17, 2006 8:43:46 AM
I know we're meant to be more persuaded of results arrived at using exotic instrumental variables that have some utterly meaningless and coincidental positive correlation with the variable of interest... and yet, I never am. Rainfall just can't be a good proxy for so many different things...
Posted by: Jacob T. Levy at Oct 17, 2006 9:05:37 AM
So kids in areas where it rains more often are more likely to have autism, and people in those areas are more likely to have cable television, therefore watching television causes autism? Is this what passes for scientific research these days? Doesn't this also prove that umbrellas cause autism?
Posted by: Hei Lun Chan at Oct 17, 2006 9:17:28 AM
And I thought this was a joke. Then I RTFA. Sigh.
Posted by: Jennifer at Oct 17, 2006 9:47:47 AM
> And I thought this was a joke.
Me too! Really. I thought it was a spoof intended to show the silliness of the belief that vaccination causes autism...
Posted by: Slocum at Oct 17, 2006 10:06:04 AM
Whatever the validity of the study's conclusions, it's interesting that there's a correlation between precipitation and autism. Also interesting that this correlation does not hold north/south in California. All in all, seems progress has been made.
Posted by: Constant at Oct 17, 2006 10:22:12 AM
I am unconvinced. Precipitation, in these states, is a coastal phenomenon and is proxying for heterogeneity in the gene pool.
How much of a proxy is it, really? There's a marked difference between central/northern Calfornia (e.g. rainy San Francisco), and southern California (dry Los Angeles), but I don't think San Francisco is appreciably more heterogeneous in its gene pool. Not to say that SF (or the "Bay Area," rather than SF proper) doesn't attract a higher proportion of nerdy engineers and programmers likely to produce autistic children. But I don't think there's a huge problem with precipitation proxying for a "heterogeneous" gene pool per se.
On the other hand, Constant says the correlation doesn't hold for north/south CA so perhaps that is the design flaw in the study -- that areas with high precipitation just happen to have a lot of the kind of people whose children are likely to come out autistic.
Posted by: Taeyoung at Oct 17, 2006 11:22:33 AM
Such vacuous analysis makes us skeptics wonder if there is really any such thing as autism.
Posted by: Robert Speirs at Oct 17, 2006 11:22:43 AM
It would be interesting to see if the spread of television in the 1940s and 1950s affected autism rates at that time. If the data are available, it should be even more revealing, especially as autism wasn't diagnosed willy-nilly then as it is today. Additionally, one might think the link would be even stronger as young children at that time would go from not watching any television whatsoever to whatever the average viewing time was from the late 50s to 1980.
Posted by: Thelonious_Nick at Oct 17, 2006 11:56:44 AM
When does autism express itself? My children's pediatrician recommended abstaining from TV until my kids are two. They're 7 mo. old now, and they seem to behave generally in a way totally inconsistent with autism (or at least my limited understanding of it). Does/can this change?
Posted by: Steve at Oct 17, 2006 12:25:59 PM
The most recent serious research hints at older parents, particularly older
fathers being an increased risk factor for autism.
Perhaps that somehow ties to gene mutation or some genetic problem.
No easy answers here.
Steve: 7 months is probably too early to tell. Abstaining from tv
altogether is tough, so make good choices (Baby Einstein videos, etc.) and
do NOT use the tv as a babysitter. Lots of books (there are cloth books
available for under 1 year).
Posted by: save_the_rustbelt at Oct 17, 2006 12:33:24 PM
Just based on Tyler's entry, I think the authors mean to use the precipitation thing as a marker for higher than average TV watching. The cable thing is interesting too. Do people with cable watch more TV? Probably. What about the programming, could that be a factor too? We don't measure the amount of TV watched in every single community, but we measure rainfall just about every where, since the two are positively correlated I think the authors are using it as a proxy for increased TV viewing.
Maybe I'm simplifying it way too much, but I hope someone will point out where I'm wrong here, here's what makes sense to me:
- Babies brains are still developing after they are born, basically the synapses get wired together after birth as they learn. Right?
- Constant simulation, or over-stimulation could cause those connections to get wired improperly.
- Could those mis-wired connections in the brain stunt the kid's ability to communicate?
Is this possible? Think how much TV programming has changed, and how much we stimulate our infants/toddlers. Any comments?
Posted by: Econ in AK at Oct 17, 2006 12:57:40 PM
Color me also unconvinced. What we're
seeing here is, if anything, simply
correlation, with no evidene of causation.
And even the correlation is sort of
second-hand. The argument is that in areas
with higher precipitation, children watch
more TV, and that TV-watching triggers
autism.
First, we don't really know whether children
in high-precipitation areas actually do
watch more TV--that's an assumption for which
no evidence is presented. Second, even if we
validata that assumption, we're still left
with only a correlation between TV-watching
and autism, with n causal mechanism.
Finally, there has to be a large number of
things, from activities of children to
physical conditions in the areas with more
precipitation (more vegetation, leading to
more pollen, for example), so the assumed
correlation of precipitation with TV watching
can't be the only possibility.
I observe that it apparently not yet published.
I wonder what the referees will have to say
about it.
Posted by: Donald A. Coffin at Oct 17, 2006 2:05:50 PM
Donald wrote:
First, we don't really know whether children in high-precipitation areas actually do watch more TV--that's an assumption for which no evidence is presented. Second, even if we validata that assumption, we're still left with only a correlation between TV-watching and autism, with n causal mechanism.
They actually do show that children in high-precipitaton areas watch more television. From the abstract:
" Using the Bureau of Labor Statistics’ American Time Use Survey, we first establish that the amount of television a young child watches is positively related to the amount of precipitation in the child’s community. This suggests that, if television is a trigger for autism, then autism should be more prevalent in communities that receive substantial precipitation. "
The results from that are in Table 2 if you are interested.
Donald wrote:
"Finally, there has to be a large number of things, from activities of children to
physical conditions in the areas with more precipitation (more vegetation, leading to more pollen, for example), so the assumed correlation of precipitation with TV watching can't be the only possibility."
I think you are right that this test is unable to differentiate between the multiple pathways that precipitation could be influencing autism diagnosis rates. I am nonetheless intrigued that there could be any causal relationship between rain and autism, as that does narrow the theories down somewhat.
Also, note they mention the Amish community - which I thought was interesting. Since Amish don't watch television (hard to do when you don't have electricity) then they should have several hundred cases of autism based on the rest of the population. But the Amish have unusually low rates of autism - fewer than ten cases, if one informal study the authors note is correct. Another piece of evidence to consider.
Posted by: Jason Voorhees at Oct 17, 2006 3:11:04 PM
Also - they do show a relationship between cable subscription and autism. So they does provide more support that the rain variable is not picking up other things.
I am more convinced by Steven Levitt's point, though. He notes television could increase parental visits to the doctor via increased parental education about autism. So you're picking up a spurious correlation, not an actual causal relationship. But that doesn't then explain why the Amish have such lower autism rates.
Posted by: Jason Voorhees at Oct 17, 2006 3:25:02 PM
TV as a contributor to autism sounds like a long shot, but autism is such a severe problem that it deserves to be investigated. So, here's a more promising natural experiment, with a much sharper increase in television watching:
The South African experience. The regime allowed no television until experimental broadcasts in 1975, followed by full-time broadcasting in 1976. South Africa is unique among countries with a large modern health system in its late, sudden adoption of television during an era when autism's defintion was more clear than during the 1940s and 1950s in America. I have no idea what the autism trends were in South Africa, but this might provide a good test.
Posted by: Steve Sailer at Oct 17, 2006 4:07:42 PM
It's PRECIPITATION -not rain necessarily- that causes autism! That must be it!
Anecdotal evidence: Four autistic siblings, raised in Germany where -as anybody who's ever lived there knows- you have four seasons aptly named Sleet, Hail, Rain and Snow (as opposed to the rest of the world which has spring, summer, fall etc). We did not have TV until I was 12. Autism most certainly must have been caused by staring out at the daily drizzle, our minds washed away as readily as dust. There you have it, proof enough. Autism is precipitated by precipitation.
Posted by: Kathleen Fasanella at Oct 17, 2006 5:45:03 PM
The problem with using proxies in a situation where it is already difficult to find properly controlled cases is that it introduces even more potential lurking variables. For example, Parents with children who have special education needs, such as autisic children, tend to migrate to areas with good special education programs, which are also likely to have better screening. Since autism has a heritable component, migration induced by parent or sibling cases can create a correlation between initial diagnosis and location. While incomes were controlled for on an individual level, average incomes will have a causitive relationship with school funding, which will have a causitive relationship with special ed funding. If cable and precipitation correlate with regional income beyond personal income effects (which they probably will in areas where major commercial centers are ports and thus costal), then it is still possible to pick up an income effect, which could only be disentangled if location was controlled for, which would control out the two proxies.
Posted by: MattXIV at Oct 17, 2006 6:41:04 PM
The Amish are not just technologically different, they're also genetically different (e.g., small gene pool), so comparisons with the Amish don't establish a technological cause.
Posted by: Mitch at Oct 17, 2006 6:49:23 PM
How does Autism correlate with droughts?
Year on year variation in precipitation would eliminate genetic and socioeconomic variation. It still wouldn't affect other precipitaion causal mechanisms (dust, pollen etc.)
Posted by: Patrick at Oct 17, 2006 7:17:24 PM
I have two cousins with autism, one of whom has never, EVER had a television in his household (you can't keep something like that a secret for long). Further, they both live in a dry region of southern Alberta.
The researchers with the electroencephalography gear seem somewhat more believable then the guys keeping tabs on the weather, the televisions...
Posted by: true dough at Oct 17, 2006 8:53:47 PM
Did anyone check to see what the correlation between rainy counties in California (um, San Jose?) and fathers who are engineers might be? Y'know, kinda geeky guys who tend to be shy and, uh, maybe get married later in life and HAVE CHILDREN LATER THAN THEIR PEERS?
And TV viewing causes autism? Don't the initial signs show up at about 18 months (shortly after a series of vaccinations and therefore the source of the post hoc ergo propter hoc link to thimerosal)? Okay, I'll give the authors the benefit of the doubt and conjecture that maybe between the ages of 0 and 18 months these kids start making the choice to stay inside to watch TV.
Ok, kids, let's open up our "Be a Published Social Scientist Kit" and start doing science! It rains in Germany, there are lots of geeky German engineers, engineer graduation rates are a proxy for autism, rain causes autism, QED. Ever notice that there are relatively fewer engineers in the Sahara? Eh? Especially the former French colonies? Eh? Eh? A nod's as good as a wink to a blind bat, knowhatahmean, squire?
Posted by: Eric H at Oct 17, 2006 10:09:55 PM
When it is raining, the parents have to stay at home rather than go out for their own romantic dinner and leave the children to nannies, who may accompany the babies to watch tv and talk with them. Then the parents occupy the tv, and deprive the childrem with the moment to talk with tv and their nannies.
So to further confirm the study, it is better to estimate the correlation between the parents' watching their favorite adult programs and the regional precipitation rate. Will the parents prefer their own TV programs than the their children's? Just as the analogy that will someonoe prefer the cash than the blue chip stock. As long as this type of preference can be established, then it may be possible to further verify the relationship of the TV and Children's Autism.
My intuition is that perhaps the issues lying behind is not that how many tv programs the children spent before the TV, but what is the porportion of activities spent before TV is helping to the children to learn the ability to communicate with others.
2D, 3D.... even 4D, 5D cannot help the children with the problem of autism, if the case is that parents are watching, and having their fun, but leaving their children playing whatever on their own.
Posted by: helen at Oct 18, 2006 1:00:17 AM
I wonder if smaller families have something to do with autism? Perhaps children without siblings to constantly annoy them are more likely to become autistic? I also think that a generation or two ago a mildly autistic person who was quite and good at performing repetitive tasks would be considered a good worker rather than suffering from a condition. When I was a child the adults in my life all seem obsessed with getting me to sit down and shut-up. Nowadays adults want children to socialize instead of just sitting down and shutting-up so it doesn't seem surprising that more children are being diagnosed as autisic now.
Posted by: Ronald Brak at Oct 18, 2006 1:09:45 AM
