How many different autism types are there? There is only one type of autism, but that one type is different in every kid. So you might say there’s many types. Remember, autism is a spectrum disorder which means that one person can be high functioning (mildly affected by ASD) and another person can be moderate and yet another can be low functioning (severely affected) or anywhere in between there. It’s a continuum. Besides that if Asperger’s is “on the spectrum” then it makes sense to say that Asperger’s Disorder is a type of autism.

Society generally classifies a few other disorders as autism or being on the autism spectrum. Often a parent whose child was diagnosed as having PDD-NOS (See below for more detail) will say their child has autism. The diagnoses are so similar and PDD-NOS is more difficult to explain and autism is more widely known. If two children were in a room, one with PDD-NOS and the other with comparable classic autism, you may not be able to tell with any certainty which was diagnosed with which disorder without seriously observing them for a length of time.

The Center for Disease Control (CDC) and the American Psychiatric Association (APA) differ on the exact words used to encompass these disabilities. The CDC refers to this group of disorders as Autism Spectrum Disorders while the APA refers to them as being Pervasive Developmental Disorders with autism being a single disorder within that group. People in the autism community, including parents and doctors, will know what you mean regardless of which term you choose to identify the disorder with.

The authority here is really the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, published by the American Psychiatric Association in 1994. The manual describes a class of 5 disorders called “Pervasive Developmental Disorders” which include:
• Autistic Disorder
• Asperger’s Disorder
• Pervasive Developmental Disorder – Not Otherwise Specified
• Childhood Disintegrative Disorder
• Rett’s Syndrome

Let me add one more that is commonly yet incorrectly associated with autism:
• Fragile X Syndrome

Autistic Disorder

Also known as classic autism, ASD, and many other popular terms. Autism is a developmental disorder that affects communication, social interaction, and behavior. Depending on the severity people with autism may also have trouble with transitions, sensitivity to light or sound or touch, or even retardation. However, it’s known that many people with autism, including my son, are bright intellectually capable individuals. In other words, many people with autism are smart! But due to autism they may not be able to express themselves. For more details see The Diagnosis or the diagnostic criteria for autism.
Asperger’s Syndrome

Asperger’s Syndrome or Asperger’s Disorder is also usually thought of as being on the autism spectrum. People with Asperger’s are high-functioning but still often have issues with socialization and don’t pick up on social cues. A social cue is unspoken body language. For example, if you’re talking on and on about the latest episode of Oprah I may get bored and send you little signals intended to get you to change the subject. Maybe I’ll roll my eyes or sigh. Maybe I’d tap my foot while gazing in another direction. Those are social cues. Also, people with Asperger’s have no clinically significant delay in language or cognitive development.
PDD-NOS

Many people believe PDD-NOS (Pervasive Developmental Disorder Not Otherwise Specified) to be on the spectrum because many of the signs and symptoms of PDD- NOS are the same as autism. I won’t argue with them. I’ve known children with PDD-NOS and they sure seem to have autism. The major symptoms match up. After all, autism is a pervasive developmental disorder too. The truth is that PDD-NOS is the catch-all, not autism. When some of the required symptoms for autism or Asperger’s or any other pervasive developmental disorder are not met the diagnostician will give the diagnosis of PDD-NOS.

You’ll hear doctors and professionals say that PDD-NOS is not autism. And they’re correct. But for every doctor and professional who says it’s not autism you’ll hear two parents who say it is. But without the official autism diagnosis many children with PDD-NOS do not receive the same services as a child with the autism diagnosis. In California the regional centers will not serve children with PDD- NOS over age 3 except in certain rare circumstances. But children with the autism diagnosis get served.
Childhood Disintegrative Disorder

After at least 2 years of seemingly typical development this disorder is marked by the loss of skills previously acquired. The areas of significant loss may be expressive and receptive language, social skills and adaptive behavior, bowel or bladder control, play, or motor skills. Many parents see this disorder quickly lead to autism.

Rett’s Syndrome

With symptoms that match up closely with the other Pervasive Developmental Disorders people with Rett’s Syndrome have one major difference: After appearing typical at birth and developing normally for the first 5 months they experience a deceleration of head growth between 5 months of age and 4 years.

Fragile X Syndrome

People with Fragile X can exhibit similar symptoms as autism, but Fragile X is not a PDD. In fact, we know that Fragile X Syndrome is genetic and we know that it’s caused by a mutation of the FMR1 gene on the X chromosome. It also features some prominent characteristics like an elongated face, large or protruding ears, etc. The confusion here comes about because many people with Fragile X also meet the diagnostic criteria for autism.