Definition of Autism
Fact Sheet Number 1 (FS1), January 2001
National Information Center for Children and Youth with Disabilities
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 child's ability to communicate, understand language, play, and relate to others.
In the diagnostic manual used to classify disabilities, the DSM-IV (American Psychiatric Association, 1994), "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 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." (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.
Some or all of the following characteristics may be observed in mild to severe forms:
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.
- 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.
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), formerly the Education of the Handicapped Act, 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.
Harris, S. (1994). Siblings of children with autism: A guide for families. Bethesda, MD: Woodbine House. (Telephone: 1-800-843-7323.)
Harris, S.L., & Weiss, M.J. (1998). Right from the start: Behavioral intervention for young children with autism: A guide for parents and professionals. Bethesda, MD: Woodbine House. (Telephone: 1-800-843-7323.)
Hart, C.A. (1993). A parent's guide to autism: Answers to the most common questions. New York: Pocket Books, Simon & Schuster Co. [Telephone: 1-800-223-2336.]
Journal of Autism and Developmental Disorders. [Available from Plenum Publishing Corporation, 233 Spring Street New York, NY 10013. Telephone: 1-800-221-9369.]
Maurice, C., Green, G., & Luce, S.C. (Eds.). (1996). Behavioral intervention for young children with autism: A manual for parents and professionals. Austin, TX: Pro-Ed. (Telephone: 1-800-897-3202.)
McClannaham, L.E., & Krantz, P.J. (1999). Activity schedules for children with autism: Teaching independent behavior. Bethesda, MD: Woodbine House. (Telephone: 1-800-843-7323.)
Powers, M.D. (Ed.). (2000). Children with autism: A parent's guide (2nd ed.). Rockville, MD: Woodbine House. [Telephone: 1-800-843-7323; (301) 897-3570.]
Schopler, E., & Mesibov, G.B. (Eds.). Books available in the "Current Issues in Autism" book series include: High-functioning individuals with autism (1992); Preschool issues in autism (1993); Behavioral issues in autism (1995); Learning and cognition in autism (1995); and Asperger syndrome or high-functioning autism? (1998). [All are available from Kluwer Academic Publishers at (781) 871-6600.]
Update, January 2001
This fact sheet is made possible through Cooperative Agreement #H326N980002 between the Academy for Educational Development and the Office of Special Education Programs. The contents of this publication do not necessarily reflect the views or policies of the Department of Education, nor does mention of trade names, commercial products or organizations imply endorsement by the U. S. Government.
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