Module 7: Autism Spectrum Disorders

AutismAutism Spectrum Disorder (Pervasive Developmental Disorder)

Autism spectrum disorder (ASD), also called pervasive developmental disorder (PDS), is a neurobiological disorder characterized by fundamental deficits in social interaction skills or communication skills, or by the presence of stereotyped (purposeless and repetitive) behaviors, interests, or activities.1

Children typically begin experiencing difficulties by or before age 3. Common features include difficulty with transitions or change, unusual sensory interests or sensitivities, an extremely narrow and intense focus of interest, and stereotyped behaviors (e.g., hand flapping, rocking, twirling). Cognitive deficits or uneven skill development are often present. The spectrum of symptoms can range from a limited desire or ability to interact with others to the more severe symptoms seen with autistic disorder.

While the symptoms of autistic disorder may be quite evident, children and adolescents with more subtle difficulties (e.g., those with social withdrawal problem; Asperger’s disorder; or a pervasive developmental disorder, not otherwise specified [PDD, NOS]) often go undiagnosed and untreated. Missed opportunities for treatment can adversely affect long-term outcomes and quality of life for these children and adolescents and their families.

Key Facts:

  • It is estimated that between 1 in 80 and 1 in 240, with an average of 1 in 110 children (an estimated prevalence of about 1 percent), in the United States have an ASD.2
  • The average age of diagnosis is approximately 3 years. However, the signs of ASD are present in most children prior to 18 months of age.3
  • Just under 50 percent of children and adolescents with an ASD meet the criteria for mental retardation (MR).4
  • ASDs are four to five times more common in males than in females, but affected females are more likely to have more severe symptoms and greater cognitive impairment.2
  • Not much is known about the causes of ASDs. However, research indicates that both genes and the environment may be involved.5


  1. National Institute of Mental Health. (2004). Autism Spectrum Disorders -- Pervasive Developmental Disorders. Bethesda, MD: National Institute of Mental Health.
  2. Centers for Disease Control and Prevention. (2009). Prevalence of Autism Spectrum Disorders-Autism and Developmental Disabilities Monitoring Network, United States, 2006. Morbidity and Mortality Weekly Report, 58 (SS-10), 1-24.
  3. Johnson, C. P. (2004). New tool helps primary care physicians diagnose autism early. AAP News, 24, 74.
  4. Plauché Johnson, C., Myers, S. M., & the Council on Children With Disabilities. (2007). Identification and Evaluation of Children With Autism Spectrum Disorders. Pediatrics, 120, 1183-1215.
  5. Centers for Disease Control and Prevention. (2009, October). Autism Spectrum Disorders Resources. Retrieved February 17, 2010, from Centers for Disease Control and Prevention Web site:

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