Each of the disorders on the autism spectrum is a neurological disorder that affects a child’s ability to communicate, understand language, play, and relate to others.

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They share some or all of the following characteristics, which can vary from mild to severe:

  • Communication problems (for example, with the use or comprehension of language);
  • Difficulty relating to people, things, and events;
  • Playing with toys and objects in unusual ways;
  • Difficulty adjusting to changes in routine or to familiar surroundings; and
  • Repetitive body movements or behaviors.

These characteristics are typically evident before the age of three.

Children with autism or one of the other disorders on the autism spectrum can differ considerably with respect to their abilities, intelligence, and behavior. Some children don’t talk at all. Others use language where phrases or conversations are repeated. Children with the most advanced language skills tend to talk about a limited range of topics and to have a hard time understanding abstract concepts. Repetitive play and limited social skills are also evident. Other common symptoms of a disorder on the autism spectrum can include unusual and sometimes uncontrolled reactions to sensory information—for instance, to loud noises, bright lights, and certain textures of food or fabrics.

What are the Specific Disorders on the Autism Spectrum?

There are five disorders classified under the umbrella category officially known as Pervasive Developmental Disorders, or PDD. As shown below, these are:

  • Autism;
  • Asperger syndrome;
  • Rett syndrome;
  • Childhood disintegrative disorder; and
  • Pervasive Developmental Disorder Not Otherwise Specified (often referred to as PDDNOS).

Although there are subtle differences and degrees of severity between these five conditions, the treatment and educational needs of a child with any of these disorders will be very similar. For that reason, the term “autism spectrum disorders”—or ASDs, as they are sometimes called— is used quite often now and is actually expected to become the official term to be used in the future.

The five conditions are defined in the Diagnostic and Statistical Manual, Fourth Edition, Text Revision (DSM-IV-TR) of the American Psychiatric Society (2000). This is also the manual used to diagnose autism and its associated disorders, as well as a wide variety of other disabilities.

At the moment, according to the 2000 edition of the DSM-IV, a diagnosis of autistic disorder (or “classic” autism) is made when a child displays 6 or more of 12 symptoms across three major areas:

  • social interaction (such as the inability to establish or maintain relationships with peers appropriate to the level of the child’s development,
  • communication (such as the absence of language or delays in its development), and
  • behavior (such as repetitive preoccupation with one or more areas of interest in a way that is abnormal in its intensity or focus).

When children display similar behaviors but do not meet the specific criteria for autistic disorder, they may be diagnosed as having one of the other disorders on the spectrum—Aspergers, Rett’s, childhood disintegrative disorder, or PDDNOS. PDDNOS (Pervasive Developmental Disorder Not Otherwise Specified) is the least specific diagnosis and typically means that a child has displayed the least specific of autistic-like symptoms or behaviors and has not met the criteria for any of the other disorders.

Terminology used with autism spectrum disorders can be a bit confusing, especially the use of PDD and PDDNOS to refer to two different things that are similar and intertwined. Still, it’s important to remember that, regardless of the specific diagnosis, treatments will be similar.

Is There Help Available?

Yes, there’s a lot of help available, beginning with the free evaluation of the child. The nation’s special education law, the Individuals with Disabilities Education Act (IDEA), requires that all children suspected of having a disability be evaluated without cost to their parents to determine if they do have a disability and, because of the disability, need special services under IDEA. Those special services are:

  • Early intervention | A system of services to support infants and toddlers with disabilities (before their 3rd birthday) and their families.
  • Special education and related services | Services available through the public school system for school-aged children, including preschoolers (ages 3-21).

Under IDEA, children with a disorder on the autism spectrum are usually found eligible for services under the category of “autism.” In the fall of 2005, more than 160,000 school-aged children (3-21) received special education and related services in the public schools under the “autism” category.

IDEA specifically defines “autism” as follows:

…..a developmental disability significantly affecting verbal and nonverbal communication and social interaction, generally evident before age three, that adversely affects a child’s educational performance.

A child who shows the characteristics of autism after age 3 could be diagnosed as having autism if the criteria above are satisfied. [34 CFR §300.8(c)(1)]

Other characteristics often associated with autism are engaging in repetitive activities and stereotyped movements, resistance to environmental change or change in daily routines, and unusual responses to sensory experiences. The term autism does not apply if the child’s educational performance is adversely affected primarily because the child has an emotional disturbance, as defined in IDEA.

To have a school-aged child evaluated for an ASD or to access special education services for a school-aged child, we recommend getting in touch with your local public school system. Calling the elementary school in your neighborhood is an excellent place to start.

What about School?

Early diagnosis and intervention are very important for children with an ASD. As we’ve mentioned, under IDEA children with an ASD may be eligible for early intervention services (birth to 3) and an educational program appropriate to their individual needs.

In addition to academic instruction, special education programs for students with ASDs focus on improving communication, social, academic, behavioral, and daily living skills. Behavior and communication problems that interfere with learning often require the assistance of a professional who is particularly knowledgeable in the autism field to develop and help 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 an ASD 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 behavioral skills. Consistency and continuity are very important for children with an ASD, and parents should always be involved in the development of their child’s program, so that learning activities, experiences, and approaches will be most effective and 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, many children and adults with a disability on the autism spectrum grow to live, work, and participate fully in their communities.

Texas Autism Supplement Facebook Live Series

Helpful Organizations

Autism Society of America

Autism Speaks


Autism Collaboration

National Autism Center

Interactive Autism Network

Organization for Autism Research


First Signs