Why has autism gone up so much? Has autism gone up so much?

Of all the questions that readers of Freakonomics ask me to explore, understanding the explosion in autism is at or near the top of the list. I haven’t read the original study, but this news report offers an interesting hypothesis about the rise in autism: older fathers. Don’t tell Dubner I’m citing Wikipedia, but there is a nice entry there devoted to the frequency of autism.

Because the term autism covers such a wide spectrum of diagnoses, even pinning down the simplest questions like “how much has autism risen?” or “what fraction of the rise is due to changing standards of diagnosis?” are hard to answer.

I’ve been asking myself lately whether an economist could bring anything useful to the study of these questions? So far I’m not sure what the answer is to that question.