What is “the spectrum”?

December 3, 2015

The word autism can sometimes be confusing.  Since autism is a spectrum disorder it means there is a wide variation of how  it impacts each person. Every child on the autism spectrum has unique abilities, symptoms, and challenges. The disorders that are considered “on the spectrum” are , however, closely related and do share a core group of symptoms.  For example almost every child on the spectrum has problems to some degree with social skills, empathy, communication, and flexible behavior.  Let’s look at the terms and descriptions of each major part of the “spectrum” of autism.

The autism spectrum disorders belong to an “umbrella” category of five childhood-onset conditions known as pervasive developmental disorders (PDD).  The three we most commonly hear about are:

  • Autism
  • Asperger’s Syndrome
  • Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS)

(Rett Syndrome and Childhood Disintegrative Disorder are also in this spectrum.)


Autism (sometimes called classic autism) is what most people think of when hearing the word “autism”. People with autistic disorder usually have significant language delays, social and communication challenges, and unusual behaviors and interests. Many people with autistic disorder also have intellectual disability.

Asperger’s Syndrome usually encompasses higher functioning children who have similar social problems and limited scope of interests as children with autistic disorder. People with Asperger syndrome usually have milder symptoms of autistic disorder. They might have social challenges and unusual behaviors and interests. However, they typically do not have problems with language or intellectual disability. (Department of Public Health)

Pervasive Developmental Disorder or PDD is also known as atypical autism. This is a kind of catch-all category for children who have some autistic behaviors but who don’t fit into other categories. People who meet some of the criteria for autistic disorder or Asperger syndrome, but not all, may be diagnosed with atypical autism. These people usually have fewer and milder symptoms than those with autistic disorder. The symptoms might cause only social and communication challenges.