Autism Spectrum Disorder Prevalence Higher Than Expected

Autism Spectrum Disorder Prevalence Higher Than Expected

May 6, 2011 12:04 PM

(SALT LAKE CITY) -- A new study released by the University of Utah, in collaboration with the Utah Department of Health, and Utah State Office of Education, demonstrates that the number of Utah children diagnosed with an autism spectrum disorder (ASD) and/or having a special education classification of autism doubled from 2002 to 2008.

The findings, published this week in the Journal of Autism and Developmental Disorders online, indicate that among 8-year-old children living in Utah in 2008, one in every 77 had an autism spectrum disorder – a 100 percent increase from the 2002 rate of one in 154.  Because approximately 55,000 babies are born every year in Utah (about 150 per day), it is estimated every day two of those children will develop an ASD. A 2006 survey of 10 nationwide sites by the Centers for Disease Control and Prevention (CDC) estimated that one out of every 110 U.S. 8-year-olds has ASD, reflecting a 57 percent increase from 2002.

“We wanted to find out whether the prevalence change reported by the CDC from 2002 to 2006 was mirrored in Utah during the same time period and whether rates would continue to increase or plateau by 2008,” says Judith Pinborough-Zimmerman, Ph.D., research assistant professor in the Department of Psychiatry at the University of Utah and lead author on the study. 

The study was funded by the Utah Registry of Autism and Developmental Disabilities (URADD), a public health program set up to study and better understand how many people in Utah have ASDs or other developmental disabilities.  URADD is funded by a variety of sources, including the Utah Department of Health, Utah State Office of Education, the University of Utah, and private donors.

ASDs are a group of childhood neurodevelopmental disorders characterized by problems with social interaction, communication, and restricted and unusual behaviors. The causes of ASDs are unknown, but researchers worldwide are investigating genetic, epidemiological, and other factors. Researchers in the University of Utah Department of Psychiatry have studied autism and other ASDs since the 1980s, looking for causes through brain imaging, genetics, and epidemiology. 

Pinborough-Zimmerman and colleagues looked at de-identified medical and education records in Utah’s three most populous counties – Davis, Salt Lake, and Utah counties. They looked for specific diagnostic codes in medical records that indicated a child had been referred to a health care provider for ASD. In education records, they looked at whether a child had been classified with autism by a team of educational specialists.

The researchers discovered that ASD prevalence steadily increased throughout the study period, but varied with the age group studied.  Prevalence was lower in younger children, suggesting that continued efforts to improve earlier diagnosis and treatment are needed.  Prevalence rates also varied depending on the record used.  Prevalence rates based on health records alone were significantly higher than those based on education records alone. The highest prevalence rate was found when health and education sources were used together.

“Previous ASD epidemiology studies have shown that increased data availability correlates with higher ASD prevalence,” says Amanda Bakian, Ph.D., epidemiologist in the University of Utah Department of Psychiatry and a contributing author to the study. “In Utah, we are fortunate to have the consistent support of health and education ascertainment sources across study years.  Still, we suspect that our 2008 prevalence findings may be an underestimate of the actual ASD prevalence in Utah.”

According to Pinborough-Zimmerman and William M. McMahon, M.D., professor and chairman of the U of U Department of Psychiatry and co-author on the study, public health studies on ASD prevalence in Utah are ongoing. Utah is one of 14 sites now participating in the CDC’s Autism and Developmental Disabilities Monitoring Network, which is examining potential reasons behind the changes in ASD prevalence.  

“It is clear that at least part of the increase in ASD prevalence is due to improved diagnosis and referral of children that previously escaped recognition as having ASD,” McMahon says. “However, our results have also strengthened our resolve to discover the multiple genetic and environmental factors contributing to this complex set of disorders, so that we can design better treatments and prevention.”

“These changing numbers represent the stories and faces of individual children with ASD,” says Pinborough-Zimmerman. “At the present time, we don’t know how to cure or prevent ASD.  Our latest findings reinforce our belief that autism will place significant demands on our health and education systems.  We need to continue planning for the health and well-being of our children.”

Parents who have concerns that their child might have an ASD are urged to contact their pediatrician or primary care provider. For more information about autism call the Utah Registry of Autism and Developmental Disabilities (801 -585-7576) or your local special education program.   

The Autism Council of Utah is a non-profit organization of parents, professionals, and agencies that has developed a FastStart checklist to help parents understand medical, educational, and other steps to help their children. This checklist is available for free download at .

Other recommended Internet resources:

American Academy of Pediatrics:

Medical Home Portal:

# # #

Media Contacts

Phil Sahm
University of Utah Health Sciences Public Affairs
Phone: 801-581-2517

Visit our News Archive for a complete list of previous News.