The lead researcher in that study commented that 38 adults does not mean that we have reason to believe there is no epidemic. It's only 38 people.
I love the spin you put on this story! (NOT)

This is no surprise to me as a parent of two such children. For years we searched for answers with our older child, but ended up with the younger, more interactive child diagnosed first (PDD-NOS) just last month. The elder is showing sign's of a slightly more severe condition (Asperger's), but no one would commit to it. He is now awaiting assessment from the same clinic that did his brother.

First, 38 people is hardly a large enough sample to justify a conclusion. Second, out of 38 participants “nearly one quarter were misdiagnosed”? Nine people is hardly significant. And the other 29 were diagnosed correctly. When it comes to developmental disorders, you will always find some people who are not diagnosed accurately. It is not an exact science. The results of this study hardly warrants such a bold headline to your story. To lend credence to your story, you publish a photo of an autistic child with a caption that has nothing to do with the article’s claims (but hey, if it’s in print it has to be true, right?). Hearst and Pulitzer would be proud – this story should be printed on yellow paper. Or in this case a yellow background. This is why I did not renew my subscription to Popular Science; lately there has been less science and more sensationalism.

Maryann L
As an educator of students with special needs for 20 years, the 'source' of autism presents may questions. While there is no doubt that the diagnosic instruments have improved and may account for some of the increase, there is much more to the issue. To discount environmental and genetic issues would be a disservice to our entire population. We must persist in scientific investigations and resist the temptation to accept improvement in diagnosis as the ultimate causality for the devastating increase in this population.