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Increasing Incidence of Autism Spectrum Disorders Continues in Indiana

Contributed by Dr. Cathy Pratt, BCBA-D,
Director, Indiana Resource Center for Autism

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In 2008, based on a sample of 8 year olds, the Centers for Disease Control (CDC) reported that the prevalence of autism had risen to 1 in 88 in American children. By 2010, using a similar sample, it was announced that the incidence had climbed to 1 in 68. Based on these latest numbers, 1 in 42 boys and 1 in 189 girls are being diagnosed with an autism spectrum disorder (ASD). Two years ago in a national telephone survey of 100,000 families, the incidence was projected at 1 in 50. (Note: Different data collection methods will often yield differing results.)

If the increasing incidence rates are accurate, what does this mean for Indiana? Since no database currently exists in Indiana with the actual numbers of people on the autism spectrum, either statewide or by county, the only real figures come from the December 1 child count data collected by the Indiana Department of Education, Department of Special Education. These data are collected from all public school districts across Indiana. The chart at the end of this article illustrates the increasing incidence of ASD since 1999.

According to the December 2010 data, the number of students served under the eligibility category ASD was 11,514. By December 2011, the count was 12,226. According to the child count data from December 2012, the number of children served under the diagnostic category of ASD was 13,020; and with the December 2013 data, the number had grown to 13,675. This year’s child count data shows an increase from the previous year of 504 for a total of 14,179. ASD is the second fastest growing category; first is Other Health Impaired at 19,727.

The number of students enrolled in Indiana’s public schools during the 2014-2015 school year is 1,009,943. Using that data and the incidence data from December 2014, approximately 14 in 1,000 students in Indiana have a diagnosis of ASD. Last year’s identification rate was 1 in 77. This year’s identification rate has increased to 1 in 71. The child count data does not include children who are not on special education service plans and are home schooled or educated in non-public schools. All who have either an IEP or special education service plan are counted.

While there is a general belief and awareness that autism spectrum disorders are on the rise, it is unclear why. Some believe that more children are being identified because the medical community and other professionals have a better understanding of autism spectrum disorders, and because the definition of autism has been expanded to encompass more individuals. Others believe that the increase is real and are advocating for research to investigate the potential causes of autism. Whether we believe the growth is because of increases in ASD or the result of changes in diagnosis, or both, the reality is that more Indiana citizens are being served under the eligibility category of ASD.

The other reality is that many of these children come with complex issues and support needs. According to the CDC, ASD commonly co-occurs with other developmental, psychiatric, neurologic, chromosomal, and genetic diagnoses. The co-occurrence of one or more non-ASD developmental diagnoses is 83%. The co-occurrence of one or more psychiatric diagnoses is 10%. The potential impact on our schools and other service delivery systems continues to be tremendous. The strain on families is very real and significant. According to the CDC, it is estimated to cost at least $17,000 more per year to care for a child with ASD compared to a child without ASD. Costs include health care, education, ASD-related therapy, family-coordinated services, and caregiver time. For a child with more severe ASD, costs per year increase to over $21,000. It is important to note that education services and an array of supports are needed for children and adults on the autism spectrum to live, learn, and work successfully in our communities.



Pratt, C. (2015). Increasing incidence of autism spectrum disorders continues in Indiana.





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