Autism diagnoses have increased in the past two decades, driven in part by a rise in milder forms of the condition, @OlgaKhazan reports. She spoke with researchers who worry that many of these diagnoses may be inaccurate:

Autism has exploded in my lifetime. That’s not an opinion, it’s a fact. We can all accept that better diagnosis and broader definitions explain some of the increase. But does anyone honestly believe that’s the whole story? More children are being diagnosed than ever before, yet we’re told not to ask what has changed. Vaccines are one of many things people ask about because the childhood vaccine schedule has expanded dramatically over the same period. Asking whether there is any connection is not anti science. It is a legitimate scientific question that should continue to be studied alongside every other possible environmental, genetic and developmental factor. Science shouldn’t be afraid of questions. It should be afraid of refusing to ask them.