WHAT IS THE DIFFERENCE BETWEEN AUTISM AND PDD?
Is there a difference between autism and pervasive developmental delay (PDD)? 
Reprinted from A Parent's Guide to Autism: Answers to the Most Common Questions, Charles Hart, Pocket Books, 1993, p. 74-76.
This questions confuses many people and the answer may confuse them even more. A very large number of people with autism, "within the autistic spectrum," or "affected by the syndrome of autism," will not be diagnosed with any of those terms. The more capable and verbal they are, the more likely their diagnosis will be called PDD (pervasive developmental delay), or, even more evasively, PDD-NOS (pervasive developmental delay, not otherwise specified).
What's going on? We are watching language change. When Dr. Leo Kanner described his first group of patients with his new-fangled label of autism, most of them had enough speech and self-help skills that they might be called high-functioning by a later generation of researchers. It was only after we discovered that some severely disabled people also had characteristics of autism that we began applying the term to people with such an incredible range of talents and abilities.
The A-word was supposed to help people, freeing them from a mistaken diagnosis like schizophrenia or mental retardation. But, as so often happens, the word became devalued through misuse. The most sensational, most severe cases of autism received the greatest publicity. The quiet, moderately disabled person (like Kanner's original patients) were unnoticed by journalists and television writers. Gradually, but surely, the public image of autism became like Barry Kaufman's first impression, that it was the most irreversible category of the profoundly disturbed and psychotic.
Today, some professionals continue using the term autism as it was used thirty or forty years ago, to cover a very broad range of symptoms connected with language and social dysfunction. Other refuse to apply that diagnosis unless the individual shows extreme symptoms in every one of the several areas. They call milder forms of the disability PDD.
Dr. Doris Allen, a developmental specialist at the Albert Einstein College of Medicine, calls PDD "a way of not diagnosing autism," a diagnosis doctors use when they want to avoid the word. PDD has become a professional euphemism, a soft term for something considered too harsh or too blunt.
People have the most well-intentioned reasons for avoiding the real diagnosis. They want to protect a child from a label that might trigger fear, rejection, and the loss of opportunities. I once heard a doctor confide to another, "I won't call this child autistic. That would be like throwing him on a trash heap where no one will ever give him a second chance."
That neurologist admits she will only diagnose autism in the most severe cases. Meaning well, she has become part of the problem. Every time doctors or psychologists refuse to call a more capable child autistic, they are narrowing the definition without scientific evidence. The diagnosis becomes more devalued, spiraling downward until there are fewer and fewer children with that diagnosis and more and more diagnosed with PDD.
As long as we have no reliable biological tests to identify autism, it will be hard to qualify these people for services. Insurance companies, government regulations, and school services all rely on guidelines for eligibility and benefits. It took nearly forty years to convince officials that children with autism needed special education and communication therapy. All of those entitlements depend on the children having the keyword in their diagnosis. When they are called PDD or PDD-NOS, they can't get the benefits they need.
Reading this, you may well ask, What difference does the diagnosis make, anyway? Who cares? Good question! Labeling people just for the sake of categories makes no sense and can do a lot of harm. However, even the most capable people with autism need special education. Unfortunately, they can't get their entitlements if their diagnosis doesn't fit the language in the regulations.
We shouldn't ask medical authorities to rewrite scientific guidelines to fit political or economic policies. When researchers discover new subtypes or better ways to identify different forms of autism, let's rewrite the regulations for services. However, at this time, the arguments about autism and PDD have no scientific value. Public attitudes and the whim of the person conducting the diagnosis, not the biological evidence, seem to determine who has autism and who has PDD.
Perhaps one day we'll offer people services based on their individual needs, not just their labels. Then, the diagnosis of autism, PDD, or Asperger's syndrome will no longer matter.
IN ENGLISH: AUTISM/PDD-NOS
Adapted from The Relationship of Autism and Pervasive Developmental Disorder, Lonnie Sears, the Indiana Resource Center for Autism, December 1990.
Educating Children with Autism: A Parent's Guide, by Michael Powers, p. 8-9, is available from
Woodbine House, 5616 Fishers Lane, Rockville, MD 20852, (800)-843-7323.
 Please note: The term "Pervasive Developmental Delay" is meant in the same manner as "Pervasive Developmental
Disorder." It is not a different diagnosis.
Please note: the views presented above may not necessarily represent those of BBB Autism.
July 24, 2002