10.1: Definitions of ASD

The Individuals with Disabilities Education Act (IDEA) of 2004 provides the following definition of autism but does not currently define ASD.

Autism means 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.

• Autism does not apply if a child’s educational performance is adversely affected primarily because the child has an emotional disturbance.
• A child who manifests the characteristics of autism after age three could be identified as having autism if the criteria of this section are satisfied (Individuals With Disabilities Education Act, Part B, Subpart A § 300.8(c)(1)(2004)).

The American Psychiatric Association (APA) Definition

The APA DSM defines ASD as the following.

1. Persistent deficits in social communication and social interaction across multiple contexts, as manifested by all of the following, currently or by history (examples are illustrative, not exhaustive; see text):
   1. Deficits in social–emotional reciprocity, ranging, for example, from abnormal social approach and failure of normal back-and-forth conversation; to reduced sharing of interests, emotions, or affect; to failure to initiate or respond to social interactions.
   2. Deficits in nonverbal communicative behaviors used for social interaction, ranging, for example, from poorly integrated verbal and nonverbal communication; to abnormalities in eye contact and body language or deficits in understanding and use of gestures; to a total lack of facial expressions and nonverbal communication.
   3. Deficits in developing, maintaining, and understanding relationships, ranging, for example, from difficulties adjusting behavior to suit various social contexts; to difficulties in sharing imaginative play or in making friends; to absences of interest in peers.
2. Restrictive, repetitive patterns of behavior, interests, or activities, as manifested by at least two of the following, currently or by history (examples are illustrative, not exhaustive, see text):
   1. Stereotyped or repetitive motor movements, use of objects, or speech (e.g., simple motor stereotypes, lining up toys or flipping objects, echolalia, idiosyncratic phrases).
   2. Insistence on sameness, inflexible adherence to routines, or ritualized patterns of verbal or nonverbal behavior (e.g., extreme distress at small changes, difficulties with transitions, rigid thinking patterns, greeting rituals, need to take [the] same route or eat [the] same food every day).
   3. Highly restricted, fixed interests that are abnormal in intensity or focus (e.g., strong attachment to or preoccupation with unusual objects, excessively circumscribed or perseverative interests).
   4. Hyper- or hypo-reactivity to sensory input or unusual interest in sensory aspects of the environment (e.g., apparent indifference to pain/temperature, adverse response to specific sounds or textures, excessive smelling or touching of objects, visual fascination with lights or movement).
3. Symptoms must be present in the early developmental period (but may not become fully manifest until social demands exceed limited capacities, or may be masked by learned strategies later in life).
4. Symptoms cause clinically significant impairment in social, occupational, or other important areas of current functioning.
5. These disturbances are not better explained by intellectual developmental disorder (intellectual disability) or global developmental delay. Intellectual developmental disorder and autism spectrum disorder frequently co-occur; to make comorbid diagnoses of autism spectrum disorder and intellectual developmental disorder, social communication should be below that expected for general developmental level.

Note: Individuals with a well-established DSM-IV diagnosis of autistic disorder, Asperger’s disorder, or pervasive developmental disorder–not otherwise specified should be given the diagnosis of autism spectrum disorder. Individuals who have marked deficits in social communication, but whose symptoms do not otherwise meet criteria for autism spectrum disorder, should be evaluated for social (pragmatic) communication disorder (DSM-5-TR, 2022, p. 56–57).

Within the note in this definition, the authors of the DSM have included a new disorder called social (pragmatic) communication disorder. This disorder includes children with only language and social impairments. In addition, students diagnosed with ASD may also be classified using severity specifiers that describe the level of support the student may require.

The Illinois Definition of ASD

“Autism Spectrum Disorder (ASD) is a developmental disability that affects an individual’s ability to communicate (e.g., the ability to use language to express one’s needs) and the ability to engage in social interaction (e.g., the ability to engage in joint attention). This disability significantly affects verbal/nonverbal communication and social interaction, generally evident before age three, that adversely affects a child’s educational performance. Often other characteristics 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. The term does not apply if a child’s educational performance is adversely affected primarily because the child has an emotional disturbance. The child’s performance, strengths, skills, deficits, and challenges associated with ASD will vary greatly from child to child.

Characteristics of Autism Spectrum Disorder (ASD)

• Intense reactions to sounds, smells, tastes, textures, lights, and/or colors
• Resistance to minor changes in routine or surroundings
• Delayed language development
• Loss of previously acquired speech or social skills
• Persistent repetition of words or phrases (echolalia)
• Difficulty understanding other people’s feelings
• Avoidance of eye contact
• Persistent preference for solitude” (Illinois State Board of Education, 2022)

Activity \(\PageIndex{1}\): Compare and Contrast

Directions: Compare and contrast the IDEA, APA, and Illinois definitions of autism and ASD. Consider the differences and similarities between the criteria included in each definition.

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Individuals With Disabilities Education Act, Part B, Subpart A § 300.8(c)(1)(2004)

American Academy of Pediatrics. (2021, April 20). Autism spectrum disorder. https://www.aap.org/en/patient-care/autism/

Illinois State Board of Education. (2022, September 27). Special education disability areas. https://www.isbe.net/Pages/Special-Education-Disability-Areas.aspx