Harvard Mental Health Letter

Are rates of autism spectrum disorders increasing?

Expanded diagnostic criteria and greater public awareness may explain why.

Results from a large study have reignited the debate about whether autism spectrum disorders have become more common — or whether expanded diagnostic criteria and increased awareness are fueling the increase in the number of cases identified.

Researchers at the U.S. Maternal and Child Health Bureau (part of the Department of Health and Human Services) analyzed data from the 2007 National Survey of Children's Health. This telephone survey collected information from 78,037 parents of children ages 3 to 17, selected through random digit dialing (a standard technique to produce a representative sample). During the survey, parents were asked whether they had ever been told by a health care provider that their child had autism, Asperger's disorder, pervasive developmental disorder, or another autism spectrum disorder.

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