Does television cause autism?

Does television cause autism? is the title of a study carried out by Cornell University economists Michael Waldman, Sean Nicholson and Nodir Adilov.

Here’s an extract from the abstract:

Using the Bureau of Labor Statistics’ American Time Use Survey, we first established 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 postively related to county-wide levels of precipitation. In our final set of tests we…to show…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 viewing being an important trigger for autism.

There is some evidence of abnormal activity in visual cortical areas 17 and 18 in autistic children, perhaps as a result of disturbances in the development of the cerebello-thalamo-cortical pathways, but there is no data on the effects of watching television on the development of visual pathways. Some studies also show an association between ADHD and early exposure to television.

The authors of the current study do not suggest how television may trigger autism, but conclude that:

…[although] our results do not definitively prove that early childhood television watching is an important trigger for autism, we believe our results provide sufficient support for the possibility that until further research can be conducted it might be prudent to act as if it were…maybe there should be additional emphasis placed on the recommendations of the American Academy of Paediatricians that early childhood television should be eliminated or at the very least quite limited.

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7 thoughts on “Does television cause autism?

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  3. It isn’t the strength of the correlation that’s important but the nature of the relationship.

    I would suggest that the researcher’s conclusions are pre-mature and spurios. Firstly, they have no good theory that accounts for why television might cause autism, just correlates. For example, they note that amish don’t have hight rates of autism and don’t watch t.v.; however, there is an obvious genetic, and huge lifestyle, difference between the amish and the rest of the population that could account for the lack of autism.

    Secondly, it is merely a correlational study and therefore caustion cannot be implied (which the research definitely does imply it). I can think of two variables they didn’t control for (as far as I can see): occupation (beyond being in the army), and population density.

    Occupation is relevant because certain jobs (for example, in the tech industry) have higher rates of autism. Obviously, techie parents children will likely watch more t.v., and due to genetic factors would be more likely to have autism – the researchers only controlled for socioeconomic status, not occupation.

    From the quick glances I’ve had it their maps, it seems that counties with more rainfall generally have higher population densities. Population density can effect both lifestyle and occupation, which may impact autism.

    In short, I think their arguement has more holes in it than grandma’s underpants. Correlation does not imply causation!!!

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  6. Does television cause autism? errrr……no.

    I’ve seen theories that the electromagnetic field generated by TV’s may cause problems if you stand real close….but autism? Doesn’t hold up.
    Now….mobile phones and microwaves, that is something else. This affects the foetus in the womb, and could quite possibly disrupt normal development.
    Heavy metals, exito toxins, degrading environment from all the pollution. All on the increase, so is autism. Co-incidence? I think not!

    Thanks

  7. I missed this very interesting post when it first appeared. I’m glad it came up again.

    If we only look at the correlation between the amount of television watching and the rate of autism, Eric Irvine is correct. There are many other possible causative variables, including the two Eric cited that could easily account for the positive correlation between television watching and autism. What makes this study interesting is that a positive correlation between the amount of precipitation and the rate of autism was found.

    If the rates of TV watching and rates of autism were entirely related to a third causative variable such as having ‘techie’ parents, we would have no reason to expect that the amount of rainfall would also be correlated with autism unless we knew that techies collect in high-precipitation communities. That’s why the authors investigated the possibility of the correlation between precipitation rates and autism rates.

    So, if we are wondering whether TV watching might be a causative factor in autism and it is known that rainfall is a causative factor in higher rates of TV watching, then one would expect to find the positive correlation between rainfall and autism that the investigators did indeed find. That finding is what lends strength to the speculation about a possible link between TV watching and autism. The finding is far from proof, but it calls out for further investigation.

    As for how TV watching might be a causative factor in autism, we do see problems with certain kinds of visual processing and in the realm of communication/intersubjectivity, particularly involving processing of facial expression among autistic individuals. At a time when the very young child’s brain is highly ‘plastic,’ there are critical aspects of brain development that rely upon interaction with the mother/caretaker in a mutually regulating relationship between mother/caretaker and the child. Television does not involve this critical two-way mutually regulating experience. It is quite reasonable, then, to ask if the amount of television watching might be a causative factor in the development of autism in some children.

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