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.