Autism spectrum disorders (ASD) – also referred to as pervasive developmental disorders (PDD) – are brain-based developmental disabilities that affect a child's ability to communicate, understand language, play and relate to others.

ASD includes autism, pervasive developmental disorder-not otherwise specified (PDD-NOS) and Asperger's syndrome. Each of these disorders has specific diagnostic criteria as outlined by the American Psychiatric Association (APA) in its Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR).

ASD affects an estimated one in 59 births (Autism and Developmental Disabilities Monitoring Network). This means that as many as 1.5 million Americans today are believed to have an autism spectrum disorder. Autism is typically diagnosed by three years of age; however, researchers at Kennedy Krieger Institute's Center for Autism and Related Disorders (CARD) are currently working to detect the signs and symptoms of autism at the earliest age possible. By detecting autism at a young age, children can gain earlier access to intervention services.

A diagnosis of autism is made when an individual displays at least six of 12 symptoms distributed across three major areas: social interaction, communication and repetitive/stereotyped patterns of behavior and interest.

Specifically, an individual with autism may have difficulty with social behaviors such as eye contact, the use of spoken words, may use gestures to enhance verbal communication, may use repetitive and stereotypical behaviors such as flapping the hands or persistently repeating words or phrases.

Individuals with Asperger's syndrome display a slightly different behavior pattern than that of individuals with autism. These individuals have difficulties with social interaction, understanding social conventions, social use of language (e.g., they may be overly talkative, be overly focused on topics of their special interest, fail to give important background information because they have problems judging their listener's informational needs, and so on), and may exhibit repetitive behaviors, unusual and intense interests, as well as be resistant to change. They acquire their language milestones on time, and have normal to superior cognitive abilities. For more information on the language and communication features of Asperger's syndrome, see Dr. Landa's chapter in the book Asperger's Syndrome, edited by Klin, Volkmar, and Sparrow (Oxford Press, 2000).

Children who do not meet the full criteria for autism or Asperger's syndrome may receive a diagnosis of pervasive developmental disorder-not otherwise specified (PDD-NOS).

Children with autism, PDD-NOS and Asperger's syndrome vary widely in abilities, intellectual functioning, and behaviors/interests. Therefore, it is important to focus on the individual child's behavioral and learning profile when making intervention decisions and recommendations.

Examples, Subsets and Synonyms for Autism/Pervasive Developmental Disorder (PDD) -- Autistic Spectrum Disorders:

  • Autism
  • Pervasive Developmental Disorder
  • Asperger's Syndrome

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