Is Autism an “Epidemic” or Are We Just Noticing More People Who Have It?

Is Autism an “Epidemic” or Are We Just Noticing More People Who Have It?

Emily Willingham (Twitter, Google+, blog) is a science writer and compulsive biologist whose work has appeared at Slate, Grist, Scientific American Guest Blog, and Double X Science, among others. She is science editor at the Thinking Person’s Guide to Autism and author of The Complete Idiot’s Guide to College Biology.
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In March the US Centers for Disease Control and Prevention (CDC) the newly measured autism prevalences for 8-year-olds in the United States, and headlines roared about a “1 in 88 autism epidemic.” The fear-mongering has led some enterprising folk to latch onto our nation’s growing chemophobia and link the rise in autism to “toxins” or other alleged insults, and some to sell their research, books, and “cures.” On the other hand, some researchers say that what we’re really seeing is likely the upshot of more awareness about autism and ever-shifting diagnostic categories and criteria.
Even though autism is now widely discussed in the media and society at large, the public and some experts alike are still stymied be a couple of the big, basic questions about the disorder: What is autism, and how do we identify—and count—it? A close look shows that the unknowns involved in both of these questions suffice to explain the reported autism boom. The disorder hasn’t actually become much more common—we’ve just developed better and more accurate ways of looking for it...

I disagree that the earlier studies ever addressed or adequately counted the change in criteria.

Trying to account for a drastic rise in childhood autism in recent years, a California study has found that it cannot be explained away by statistical anomalies or by a growing public awareness that might have led more parents to report the disorder.

But the study's authors, who reported their findings yesterday to the California Legislature, said they were at a loss to explain the reasons for what they called an epidemic of autism, the mysterious brain disorder that affects a person's ability to form relationships and to behave normally in everyday life.

''Autism is on the rise in the state, and we still do not know why,'' said the lead author, Dr. Robert S. Byrd, an epidemiologist and pediatrician at the University of California at Davis. ''The results are, without a doubt, sobering.''

As diagnoses of autism have increased throughout the nation, experts and parents have cast about for possible explanations, including genetics, birth injuries and childhood immunizations. The California study found that none of these factors could explain an increase of the magnitude reported there -- more than triple from 1987 to 1998.

The world's first ever study into the prevalence of autism spectrum disorders among adults shows that one in every hundred adults living in households has the condition – broadly the same rate as that cited for children.

While studies have been carried out into the prevalence of autism spectrum disorders among children, the report from The NHS Information Centre is the first attempt to find and count adults and older people in the community with an autism spectrum disorder, including asperger syndrome.

Up until now, little was known about how autism affected people over the course of a lifetime. For example, autism rates could have been lower among older age groups because people had gradually recovered from the condition or died prematurely.

However, the study suggests that this is not the case and that prevalence of autism spectrum disorder remains broadly level across all age bands.

The survey fails to support suggestions of a link between the mumps, measles and rubella (MMR) vaccine and the condition. This is because, if MMR were a factor in the development of the condition, prevalence would be expected to be higher among children and younger adult age bands because MMR was introduced in 1990/91 and only those currently aged in their early twenties or younger have been routinely offered it.