Autism and Pervasive Developmental Disorder (PDD) are developmental disabilities that share many of the same characteristics. Usually evident by age three, autism and PDD are neurological disorders that affect a child’s ability to communicate, understand language, play, and relate to others.
In the diagnostic manual used to classify disabilities, the DSM-IV-TR (American Psychiatric Association, 2000), “autistic disorder” is listed as a category under the heading of “Pervasive Developmental Disorders.” A diagnosis of autistic disorder is made when an individual displays 6 or more of 12 symptoms listed across three major areas: (a) social interaction, (b) communication, and (c) behavior. When children display similar behaviors but do not meet the criteria for autistic disorder, they may receive a diagnosis of Pervasive Developmental Disorder-NOS (not otherwise specified, or PDD-NOS). Although the diagnosis is referred to asPDDNOS, throughout the remainder of this fact sheet, it will be referred simply as PDD, as it is more commonly known.
Autistic disorder is one of the disabilities specifically defined in the Individuals with Disabilities Education Act (IDEA), the federal legislation under which children and youth with disabilities receive special education and related services. IDEA, which uses the term “autism,” defines the disorder as “a developmental disability significantly affecting verbal and nonverbal communication and social interaction, generally evident before age 3, that adversely affects a child’s educational performance. Other characteristics often associated with autism are engagement in repetitive activities and stereotyped movements, resistance to environmental change or change in daily routines, and unusual responses to sensory experiences.”
