What Is (or Was) PDD-NOS? Is It the Same Thing As Autism?

PDD-NOS no longer exists -- but the symptoms are still around!

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If you've been involved with the world of autism for more than a few years, you have probably heard of a disorder called PDD-NOS (pervasive developmental disorder not otherwise specified). You may even have a child who received the PDD-NOS diagnosis. You might have been told that it's a diagnosis that means "on the autism spectrum, but not falling within any of the existing specific categories of autism."

Why PDD-NOS No Longer Exists

Today, you can search the diagnostic manual forever, and never find such a diagnosis. That's because it existed only for a couple of decades -- and then disappeared forever. That doesn't mean that the symptoms vanished, or even that there are fewer people with the symptoms associated with PDD-NOS.  Rather, it means that  PDD-NOS is an outdated diagnostic category.

To explain more fully: up until May 2013, there were five disorders that fell under the category of "pervasive developmental disorders" (PDDs). These included autism, Asperger syndrome, Rett syndrome, fragile X syndrome, and PDD-NOS. Autism, Asperger syndrome, Rett syndrome and fragile X were all specifically described in the DSM-IV -- the manual that practitioners used to diagnose neurological disorders. 

Once the DSM-5 was published in 2013, however, the term PDD-NOS "disappeared" from the diagnostic literature.

  Most people who once had the PDD-NOS diagnosis would now be considered to have an "autism spectrum" diagnosis instead.

So... What WAS PDD-NOS?                                                                                                                                                                                                                   Back in the day, before 2013 and the DSM-5, many children had some symptoms of one PDD and some symptoms of another, but not enough of any one of the four specific disorders to receive a diagnosis.

Thus, they did have a PDD -- but they did not have Rett syndrome, fragile X, Asperger syndrome, or autism. As a result, they received the catch-all diagnosis of PDD-NOS.

On the up side, PDD-NOS did provide a nice option for doctors looking at children who had a range of differences that didn't seem to fit any particular category. On the down side, the category was so general and so vague that it told parents, therapists, and teachers very little. Unlike the now-defunct Asperger syndrome category, which was another term for "high functioning autism," PDD-NOS could mean virtually anything.

Children (and adults) with PDD-NOS might have had just "a touch of autism."  On the other hand, he might have had severe delays in language and communication skills along with cognitive delays and other issues, but still not qualify for a specific autism diagnosis.

While many still mourn the loss of the very useful Aspergers category (and many still use the term!), very few seem to miss PDD-NOS!


Autism Fact Sheet Office of Communications and Public Liaison National Institute of Neurological Disorders and Stroke National Institutes of Health.

April 2006.]

Pervasive Developmental Disorders Fact Sheet 20 (FS20 1998, Resources updated, October 2003. A publication of the National Dissemination Center for Children with Disabilities.

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