Harvard Mental Health Letter

Are rates of autism spectrum disorders increasing?

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. In the survey, 913 parents said their child was currently diagnosed with an autism spectrum disorder, and another 453 said their child once had such a diagnosis but no longer did. Based on the responses, the investigators estimated that 110 U.S. children out of 10,000 currently have an autism spectrum disorder — or roughly one in every 91. If confirmed by other studies, this would mean that autism spectrum disorders are now slightly more common than schizophrenia (which affects about one in 100 Americans).
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