Definition

**Autism and Pervasive Developmental Disorder-NOS (not otherwise specified) are developmental disabilities that share many of the same characteristics. Usually evident by age three, autism and PDD-NOS are neurological disorders that affect a childs ability to communicate, understand language, play, and relate to others.

In the diagnostic manual used to classify disabilities, the DSM-IV (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: social interaction, communication, and 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 (PDD not otherwise specified). Although the diagnosis is referred to as PDD-NOS, throughout the remainder of this fact sheet, we will refer to the diagnosis 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, usually evident before age 3, that adversely affects a childs 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. (In keeping with the IDEA and the way in which this disorder is generally referred to in the field, we will use the term autism throughout the remainder of this fact sheet.)

Due to the similarity of behaviors associated with autism and PDD, use of the term pervasive developmental disorder has caused some confusion among parents and professionals. However, the treatment and educational needs are similar for both diagnoses.

**Autism and PDD occur in approximately 5 to 15 per 10,000 births. These disorders are four times more common in boys than girls.

**The causes of autism and PDD are unknown. Currently, researchers are investigating areas such as neurological damage and biochemical imbalance in the brain. These disorders are not caused by psychological factors.

Characteristics

**Some or all of the following characteristics may be observed in mind to severe forms:

Communication problems (e.g., using and understanding language); Difficulty in relating to people, objects, and events; Unusual play with toys and other objects; Difficulty with changes in routine or familiar surroundings; and Repetitive body movements or behavior patterns.

Children with autism or PDD vary widely in abilities, intelligence, and behaviors. Some children do not speak; others have limited language that often includes repeated phrases or conversations. People with more advanced language skills tend to use a small range of topics and have difficulty with abstract concepts. Repetitive play skills, a limited range of interests, and impaired social skills are generally evident as well. Unusual responses to sensory information -- for example, loud noises, lights, certain textures of food or fabrics -- are also common.

Educational Implications

**Early diagnosis and appropriate educational programs are very important to children with autism or PDD. Public Law 105-17, the Individuals with Disabilities Education Act (IDEA), includes autism as a disability category. From the age of three, children with autism and PDD are eligible for an educational program appropriate to their individual needs. Educational programs for students with autism or PDD focus on improving communication, social, academic, behavioral, and daily living skills. Behavior and communication problems that interfere with learning sometimes require the assistance of a knowledgeable professional in the autism field who develops and helps to implement a plan which can be carried out at home and school.

The classroom environment should be structured so that the program is consistent and predictable. Students with autism or PDD learn better and are less confused when information is presented visually as well as verbally. Interaction with nondisabled peers is also important, for these students provide models of appropriate language, social, and behavior skills. To overcome frequent problems in generalizing skills learned at school, it is very important to develop programs with parents, so that learning activities, experiences, and approaches can be carried over into the home and community.

With educational programs designed to meet a student's individual needs and specialized adult support services in employment and living arrangements, children and adults with autism or PDD can live and work in the community.