What are the global trends in the incidence of autism spectrum disorder (ASD)?

Updated: Sep 30, 2019
  • Author: James Robert Brasic, MD, MPH; Chief Editor: Caroly Pataki, MD  more...
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Answer

Reported rates of autism spectrum disorder have been rising in many countries over the past 2 decades. [91, 92] It remains unclear how much of these data represent an actual increase and how much reflect changes in diagnostic definitions and practices, as well as increasing awareness among the general public and within the medical profession. [93, 94, 95] Further epidemiologic studies are needed.

However, such studies of relatively uncommon conditions such as autism spectrum disorder are expensive. A suitable research strategy is the administration of multiple screenings in a population, each time identifying more likely subjects for detailed investigation.

For example, a reporting tool, such as the Autism Screening Checklist, can be distributed to all parents and guardians in a target population. See the image below.

The significance of answers to individual Autism S The significance of answers to individual Autism Screening Checklist items is as follows: Item 1- A "yes" occurs in healthy children and children with some pervasive developmental disorders; a "no" occurs in children with autism, Rett syndrome, and other developmental disorders. Item 2 - A "yes" occurs in healthy children, not children with autism. Item 3 - A "yes" occurs in healthy children and children with Asperger syndrome (ie, high-functioning autism); a "no" occurs in children with Rett syndrome; children with autism may elicit a "yes" or a "no"; some children with autism never speak; some children with autism may develop speech normally and then experience a regression with the loss of speech. Item 4 - A "yes" occurs in healthy children and children with Asperger syndrome and some other pervasive developmental disorders; a "no" occurs in children with developmental disorders; children with autism may elicit a "yes" or a "no." Items 5-10 - Scores of "yes" occur in some children with autism and in children with other disorders. Item 11 – A "yes" occurs in healthy children; a "no" occurs in some children with autism and in children with other disorders. Items 12, 13 - Scores of "yes" occur in some children with autism and in children with other disorders. Items 14-19 - Scores of "yes" occur in children with schizophrenia and other disorders, not in children with autism, Asperger syndrome, or other autism spectrum disorders. The higher the total score for items 5-10, 12, and 13 on the Autism Screening Checklist, the more likely the presence of an autism spectrum disorder.

The checklist identifies those children with characteristics of an autism spectrum disorder and differentiates them from children with child-onset schizophrenia. (See History).


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