The prevalence of autism spectrum disorders (ASD) had risen markedly in recent years. However, it is too soon to know whether these data indicate a true increase in the numbers of children with this condition, or a growing recognition of the diagnosis by parents and health professionals.
Autism spectrum disorders include autistic disorder, pervasive developmental disorder-not otherwise specified, and Asperger’s Disorder. ASDs arise in childhood (generally before age three) and continue throughout a person’s life. Children with ASD exhibit a wide range of characteristics, but have in common problems with social and communication
skills. Other features typical of children with ASD are unusual patterns of learning, paying attention, and reacting to sensory stimuli. The term, “spectrum,” conveys the fact that, among children with ASD, symptoms occur on a broad continuum of both type and severity. Children with ASD have highly idiosyncratic characteristics, which may include exceptionally advanced abilities.
Although there is some evidence of a genetic association, currently diagnosis is made on the basis of clinical observation
only. In addition to genetic factors, in utero insults, brain abnormalities, neurochemical imbalances, and immune-system problems have been implicated as contributing to autism. Evidence from a recent Swedish study suggests that preterm births, and more specifically, the prenatal and neonatal complications that may accompany such births, may play a role in the risk for autistic disorders. Among those diagnosed with ASDs, socioeconomic class appears to play an important role in mitigating symptoms. Non-Hispanic white children of highly educated mothers are much more likely to experience rapid improvement in functioning than other children.
The lifetime societal costs associated with autism have been estimated at $3.2 million per person with autism. These costs are driven largely by behavioral therapies in childhood, and extensive adult care, along with large indirect societal costs due to lost productivity.
In a nationally representative survey, the prevalence of a current ASD diagnosis among children ages 3-17, as reported by parents, grew from 1.0 percent to 1.8 percent between 2007 and 2011/12, a 72 percent increase in four years, which translates into an estimated additional 493,000 U.S. children with ASD. (Figure 1) A separate estimate, derived from health and education records in 14 study sites around the U.S., puts the average prevalence among eight-year-olds in 2008 at more than one percent (11.3 per thousand). However, there have been changes over time in the definition and identification of these conditions, including increased physician and parental awareness, complicating efforts to assess changes in prevalence. 
Differences by Gender
Boys are more than four times more likely than girls to be diagnosed with ASD. In 2011/12, the estimated prevalence among boys was 2.9 percent, compared to 0.7 percent among girls. (Figure 1)
Differences by Race and Hispanic Origin
White children are more likely than blacks and Hispanics to be diagnosed with ASD. Among white children, prevalence in 2011/12 was 2.1 percent; among Hispanic and black children prevalence was 1.5 and 1.4 percent, respectively. Increases since 2007 have been greatest among black children, more than doubling over that period. (Figure 2)
State and Local Estimates
Estimates by state from the 2009-10 National Survey of Children with Special Health Care Needs are available from the Data Resource for Child & Adolescent Health.
Prevalence data for sites participating in the Autism and Developmental Disabilities Monitoring Network (eight states in 2004, 11 states in 2006, 14 states in 2008) are available here.
Prevalence data from studies conducted in selected countries are available from the National Center on Birth Defects and Disabilities.
Through its Healthy People 2020 Initiative, the federal government has set a national goal to increase the proportion of young children that are screened for autism spectrum disorder (ASD) by age two from 23 to 25 percent. There are also goals to increase the proportion of children with ASD who were evaluated before age three, and who enrolled in special services before age four.
More information is available here. (Goal MICH 29)
What Works to Make Progress on the Indicator
Research to date has identified few interventions that can be considered more than “promising.” There are no credible claims for any intervention that can result in “cure” or “recovery” from autism or ASD. Some programs have demonstrated effectiveness in addressing specific symptoms or promoting specific skills.
In addition to evaluating the evidence for the overall effectiveness of an intervention, it is important to ascertain the
appropriateness of any given approach to the needs of the individual child with ASD. A 2005 review of 33 methods
designed for use with children and youth with ASD identified four practices that met criteria for “scientifically based”—i.e., those that have “significant and convincing empirical efficacy and support.” These were applied behavior analysis, discrete trial training, pivotal response training, and the program, Learning Experiences: An Alternative Program for
Preschoolers and Parents (LEAP).
- Children with Special Health Care Needs
- Individualized Education Plans
- Children with Limitations
- Screening and Risk for Developmental Delay
Autism Spectrum Disorders include autistic and other “pervasive developmental” disorders: Rett’s Disorder, child disintegrative disorder, Asperger’s disorder, and pervasive developmental disorder-not otherwise specified.
Child Trends’ original analyses of data from the 2007 and 2011/12 National Survey of Children’s Health.
Raw Data Source
National Survey of Children’s Health.
Centers for Disease Control and Prevention. (2009). Prevalence of autism spectrum disorders–Autism and Developmental Disabilities Monitoring Network, United States, 2006. Surveillance Summaries, December 18, 2009, MMWR, 58
(No. SS-10), 1-24.
Herbert, J. D., Sharp, I. R., and Gaudiano, B. A. (2002). Separating fact from fiction in the etiology and treatment of autism: A scientific review of the evidence. The Scientific Review of Mental Health Practice, 1 (No. 1), retrieved from www.srmhp.org/0101/autism.html.
Buchmayer, S., Johansson, S, Johansson, A., Hultman, C. M., Sparen, P., and Cnattingius, S. (2009). Can association between preterm birth and autism be explained by maternal or neonatal morbidity? Pediatrics, 124(5), e817-e825.
Fountain, C., Winter, A.S., & Bearman, P.S. (2012). Six developmental trajectories characterize children with autism, Pediatrics 129(5). Available at http://pediatrics.aappublications.org/content/early/2012/03/28/peds.2011-1601
Centers for Disease Control and Prevention. (2012) Community Report From the Autism and Developmental Disabilities Monitoring (ADDM) Network: Prevalence of autism spectrum disorders (ASDs) among multiple areas of the United States in 2008. National Center on Birth Defects and Developmental Disabilities. Available at http://www.cdc.gov/ncbddd/autism/documents/ADDM-2012-Community-Report.pdf.
Simpson, R. L. (2005). Evidence-based practices and students with autism spectrum disorders. Focus on Autism and Other Developmental Disabilities, 20 (No. 3), 140-149. Further information on the programs cited may be found by following the references cited in this article.
Child Trends. (2013). Autism Spectrum Disorders. Available at: https://www.childtrends.org/?indicators=autism-spectrum-disordersLast updated: May 2013