Autism 101: A basic definition

What is autism? The Autism Society of America, “the nation’s leading grassroots autism organization,” founded in 1965, says on their introductory web page that “Autism is a complex developmental disability that […] affects a person’s ability to communicate and interact with others. Autism is defined by a certain set of behaviors and is a ‘spectrum disorder’ that affects individuals differently and to varying degrees.”

The term “spectrum disorder” is very important here, because the severity of the disability varies from person to person.

Stephen Shore, mentioned in my post “Understanding Autism (for Dummies, by Stephen Shore),” posted on his web site the “autism spectrum wedge” – a diagram of the autism spectrum severity created by Dr. Dan Rosenn, MD. (scroll down the page to the second graph to see it)

On the left are individuals whose autism is severe and debilitating – they are not only non-verbal, they may be unable to show to the “outside” world what they think, how they feel, or what they want or don’t want. It may look like they are completely unaware of what’s happening around them, they seem to be in their own world. (In reality, we now know they are aware of their surroundings, but that’s a topic for another post)

Stephen Shore places himself as a non-verbal four-year-old in the middle of the wedge – true, he was non-verbal, but despite not being able to talk, he was able to interact with his mother. The different shapes in the wedge are supposed to represent a variation in autistic characteristics – there is more variety among individuals with moderate autism in how they behave and which functions are impaired.

On the right side of the wedge are people with the so called “HFA – highly functioning autism” or “AS – the Asperger Syndrome.” At this point on the spectrum, the variation among people is the largest and each person’s autism might manifest itself in a completely different manner.

So what do they all have in common?

You can go to the Centers for Disease Control and Prevention section “Autism Information Center” to see the full definition for each disorder.

But in short, according to the Diagnostic and Statistical Manual (DSM), fourth edition, published by the American Psychiatric Association in 1994, 299.00 – Autistic Disorder—is characterized by:

1) qualitative impairment in social interaction

2) qualitative impairments in communication, and

3) restricted, repetitive and stereotyped patterns of behavior, interest, and activities.

The DSM makes a distinction between 299.00 and Asperger’s Disorder, which shares the code 299.80 with Pervasive Developmental Disorder Not Otherwise Specified (Including Atypical Autism). But only the requirement for “qualitative impairments in communication” is missing from the definition for 299.80.

The common part is the “impairment in social interaction” and the “restricted, repetitive and stereotyped patterns of behavior, interest, and activities.”

By the way, the definition for the Pervasive Developmental Disorder Not Otherwise Specified (Including Atypical Autism), or PDD-NOS for short, does not have a specific list of criteria. It just states:

“This category should be used when there is a severe and pervasive impairment in the development of reciprocal social interaction or verbal and nonverbal communication skills, or when stereotyped behavior, interests, and activities are present, but the criteria are not met for a specific Pervasive Developmental Disorder, Schizophrenia, Schizotypal Personality Disorder, or Avoidant Personality Disorder. For example, this category includes atypical autism – presentations that do not meet the criteria for Autistic Disorder because of late age of onset, atypical symptomatology, or subthreshold symptomatology, or all of these.”

The most important word in this definition is “or.” To get a diagnosis of PDD-NOS not all three areas (social, communication, and behavior) from the autism diagnosis have to be impaired; it could be just one. So a child could get a diagnosis of PDD-NOS even if he or she was not exhibiting “restricted, repetitive and stereotyped patterns of behavior, interest, and activities”— the requirement for both the Autistic Disorder and the Asperger’s Disorder diagnosis.

That’s why one of the specialists that saw our son made a diagnosis of PDD-NOS, because his “peer relationships” were not “appropriate to developmental level,” his “ability to initiate or sustain a conversation with others” was also impaired, and he was exhibiting “lack of varied, spontaneous make-believe play or social imitative play appropriate to developmental level.”


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