The Medical Minute: New data on autism incidence rates

By Mariah Arnold and Lindsay Milliken

National Autism Awareness Month this April carries extra meaning in the wake of the Centers for Disease Control and Prevention’s (CDC) new report on autism incidence rates. The CDC report now estimates that one in 88 American children have Autism Spectrum Disorder (ASD) based on the Autism and Developmental Disabilities Monitoring (ADDM) Network 2008 surveillance year. For this estimated prevalence, ADDM used children’s evaluation records (aged 8 years) from 14 states.

ASD is a group of neurodevelopmental disorders marked by impairments in social interaction and communication, as well as restricted and repetitive behaviors. Symptoms typically manifest before the age of 3, persisting throughout the lifetime. The number of individuals diagnosed with ASD has been increasing for decades and rapidly rising over recent years causing debate about prevalence and etiology.

In the new findings, published in the CDC’s Morbidity and Mortality Weekly Report, boys were almost five times more likely to be diagnosed than girls when comparing the rate of one in 54; to one in 252 for girls. Results indicate an increase from previous statistics published by the CDC. Comparing the 2008 results to data from 2006, diagnosis increased more than 20 percent. The estimated rate in 2006 was approximately one in 110.

The reasons behind the rising prevalence of ASDs are not completely understood. According to the CDC, increased awareness and access to services for these disorders likely play a role as the ADDM network is better able to identify children with ASD over time. However, the extent to which the increased estimation of prevalence reflects these factors, rather than a true increase in the prevalence of ASDs, is unknown.

The rapid rise in prevalence might also be affected by the release of the revised Diagnostic and Statistical Manual of Mental Disorders (DSM-5) in 2013. Due to changes to the clinical definition of ASD, more marked symptoms may be required to meet criteria for a diagnosis. Amanda Pearl, a Penn State Hershey clinical psychologist, believes that individuals who are currently diagnosed with an ASD will not lose their diagnosis or services with the change. Addressing the future use of the proposed criteria, Pearl notes that empirical data suggests that this will result in increased specificity of diagnosis and unfortunately, some critics are concerned this will come at a cost of decreased sensitivity.

As prevalence estimates of ASD increase, it is an imperative that we identify children with autism at an early age to access appropriate interventions. Additionally, early diagnosis can help minimize the need for expensive services later in life.

The Autism Services, Education, Resources, and Training (ASERT) centers, created by the PA Bureau of Autism Services, have reacted to the estimated increase in prevalence and need for better services by expanding research projects and the ASERT Resource Center. The Central PA ASERT Center includes the collaboration between Penn State Hershey, Philhaven Center for Autism and Developmental Disabilities and The Vista Foundation.

The mission of the ASERT centers is to improve regional access to quality services and interventions, provide information and support to families, train professionals in best practices, and facilitate collaboration among providers throughout the commonwealth. For more information, visit AutismCentralPA.org or call the Resource Center at 1-877-231-4244.

Mariah Arnold is a research coordinator in the Division of Autism Services at Penn State College of Medicine. Lindsay Milliken is a research intern in the Division of Autism Services at Penn State College of Medicine.

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Last Updated May 01, 2012