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The Centers for Disease Control and Prevention (CDC) continue to report a substantial increase in the estimated prevalence of autistic spectrum disorders (ASDs) in children at age 8 years — from 6 per 1000 children (1 in 150) in 2002 and 8 per 1000 children (1 in 125) in 2006 to 11.3 per 1000 (1 in 88) in 2008.
These serial estimates were determined through The Autism and Developmental Disabilities Monitoring (ADDM) Network using the same case definition and surveillance methods. Each of the 14 surveillance sites was selected through a competitive review process on the basis of their ability to conduct records-based surveillance of ASDs. Data were obtained from general pediatric health clinics, developmental disability clinics, and special education programs. Trained clinicians reviewed the records and determined ASD status based on standard diagnostic criteria. None of the children were evaluated in person by a member of the research team. The 2008 estimate represents a 23% increase compared with the 2006 estimate and a 73% increase compared with 2002.
Centers for Disease Control and Prevention. Prevalence of autism spectrum disorders — Autism and developmental disabilities monitoring network, 14 sites, United States, 2008. MMWR Surveill Summ 2012 Mar 30; 61:1.
Comment
The reported increase in autistic spectrum disorder prevalence from 1 per 1000 children in the early 1990s to 1 per 88 children in 2008 has generated considerable concern. But do the reported increases in the ADDM surveillance system reflect actual increasing prevalence of ASD among young children? Potential explanations for the apparent increase include an expanded clinical definition of autism since 1995 that includes a wider spectrum of behaviors and developmental criteria; greater awareness of autistic behaviors by clinicians, teachers, and parents; and an increase in available services for children with ASD in schools and in the community. My hunch is that these factors play a large role in the apparent increase in ASD prevalence, perhaps in some communities more than in others. Also, the results of this records-based surveillance study should be interpreted with caution because of the methodology used for ascertainment of children with ASDs and the limited number of study sites that are not necessarily nationally representative. Perhaps the time has come to ask: “Is there value to more prevalence studies or should the research community target more funding for discoveries of the genetic and environmental etiologies of autism?” Hopefully, such research will lead to treatments and preventive strategies.