I’m not generally into doing the nitty gritty details of medicalistic categories. But I’ve ended up having to write things like this out (mostly from memory) so many times lately, that I thought I’d write it down in one place and get it over with. Be aware that I do not agree with the official ways that autism is divided up. When I write this, I’m reporting how something is used, I’m not agreeing with the usage. When I talk about PDD-NOS (pervasive developmental disorder, not otherwise specified) being used “correctly” and “incorrectly” below, I mean “in accordance with official criteria” and “outside of accordance with official criteria”.
A lot of people online say things like:
“PDD-NOS entails a language delay.”
“PDD-NOS kids have a specific way of interacting socially that autism and Asperger kids don’t.”
“PDD-NOS is the intermediary between autism and Asperger’s.”
“PDD-NOS refers to mild autism.”
“PDD-NOS refers to high-functioning autism.”
“PDD-NOS refers to very low-functioning autism.”
“PDD-NOS is more severe than Asperger’s but less severe than autism.”
And so on and so forth.
As far as that autism spectrum severity wedge goes, with “Kanner’s” autism at one end, “Asperger’s” and “high functioning” autism at the other, and “PDD-NOS” in the middle, with “AS/HFA” being the “most varied presentation,” I beg to differ in a number of areas, and would direct people both to this post (which seems to show PDD-NOS is the most varied of any autism category, just by its nature) and to my old post on what does “Kanner” actually mean?, because, to quote Inigo Montoya, “You keep using that word. I do not think it means, what you think it means.” In several respects.
Even though the official categories of autism and Asperger’s can be indistinct, they are nowhere near so indistinct as the category of PDD-NOS. This is because PDD-NOS, far from being a distinct thing, is meant for anyone who doesn’t fit into a few narrower categories. It’s also frequently used outside of accordance with the actual criteria.
Here’s how it’s used in ways that the criteria don’t even cover:
- A doctor sees an autistic person and says, “This person cannot be autistic, because he makes eye contact, or shows affection, or likes to socialize (even if in unusual ways), or seems aware people exist, or has a normal IQ.” In other words, the person does not fit the doctor’s stereotype of autism even though they might meet official criteria for autism or Asperger.
Roy Grinker describes his daughter’s diagnosis in the nineties:
[The psychiatrist] showed us the criteria for autism and related disorders, all classified under the heading of “PDD,” and then drew our attention to PDD-NOS, Isabel’s diagnosis. But it seemed to me that Isabel did meet the criteria for autism. She couldn’t make friends or communicate with words or gestures. She used repetitive speech and was preoccupied with lining things up in a row. So why didn’t he say she was autistic?
He explained that while it was true that Isabel had most of the features of autism, she had them to a lesser degree than many of the other children he had seen in his years of practice as a child psychiatrist, and she showed no evidence of being mentally retarded (though the absence of mental retardation never rules out an autism diagnosis). In retrospect, I think he may have been afraid to give us a devastating diagnosis like autism when Isabel was so young and in some ways functioning at a higher level than the children he had seen. As a child psychiatrist from Fairfield County, Connecticut, told me recently: “Things are different now. Even in the mid-90s, autism used to be like the ‘c’ word [cancer], and I didn’t use it if I didn’t have to. So it was only the severe cases that got an autism diagnosis from me. The others got ‘PDD-NOS’.”
In fact, I remember that, despite knowing little about autism, I felt happy that Isabel had PDD-NOS instead of autism. I didn’t realize then that, over time, PDD-NOS would prove to be an ambiguous and cumbersome diagnosis, that it would morph into “autism” or “autism spectrum disorder,” and that I’d rarely use the term PDD again. Today, Isabel is simply a child with “autism”.
(from Unstrange Minds: Remapping the World of Autism by Roy Grinker.)
- A doctor sees an autistic person and says, “This person meets the criteria for autism, but autism means hopeless, and I don’t want to label this person hopeless,” or “This person meets the criteria for autism or Asperger’s, but will get better services under PDD-NOS.” This was part of the rationale for diagnosing me on paper as PDD-NOS in the nineties, while telling my parents orally that I was autistic.
- A doctor meets an autistic teenager or adult with an ambiguous early history, and proceeds to diagnose PDD-NOS as a way of saying “I don’t have all the data.” (For instance, I was never told until I was practically an adult that I lost some speech early on, and I have no idea if my doctors had been told that either. A middle-aged friend of mine has a PDD-NOS diagnosis because they don’t know her early history despite the fact that she seems to fit the autism criteria.)
- A doctor has an aversion to “labeling” people and only gives them -NOS diagnoses because they “seem less like a label” somehow. (I had a psychologist like this.)
- A doctor sees that a person has another diagnosis and doesn’t want to tease out what’s autistic and what’s from this other diagnosis. (I’ve met clearly-autistic people with cerebral palsy who got diagnosed as PDD-NOS because of this, even though they met criteria for autism or Asperger’s. This can also happen to people with Down’s syndrome.)
Okay, so that’s just the number of ways that are not exactly in keeping with the real criteria. Some of them used to be used more frequently than they are now, but many are still used this way today. Those are not actually in accordance with the criteria, they’re in accordance with the doctors’ wishes or prejudices for various reasons.
Even what meets the official criteria, though, is still pretty varied. Here’s the official criteria. I’m going to include both DSM-IV and DSM-IV-TR criteria since that changeover is fairly recent (2000) and there are still kids diagnosed prior to then who have this diagnosis, and also ICD-10:
DSM-IV criteria for PDD-NOS:
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, Schizotypical 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 sub threshold symptomatology, or all of these.
DSM-IV-TR criteria for PDD-NOS:
This category should be used when there is a severe and pervasive impairment in the development of reciprocal social interaction associated with impairment in either verbal and nonverbal communication skills, or with the presence of stereotyped behavior, interests, and activities, but the criteria are not met for a specific Pervasive Developmental Disorder, Schizophrenia, Schizotypal Personality Disorder, or Avoidant Personality Disorder.
ICD-10 criteria for atypical autism:
A pervasive developmental disorder that differs from autism in terms either of age of onset or of failure to fulfil all three sets of diagnostic criteria. Thus, abnormal and/or impaired development becomes manifest for the first time only after age 3 years; and/or there are insufficient demonstrable abnormalities in one or two of the three areas of psychopathology required for the diagnosis of autism (namely, reciprocal social interactions, communication, and restrictive, stereotyped, repetitive behaviour) in spite of characteristic abnormalities in the other area(s). Atypical autism arises most often in profoundly retarded individuals whose very low level of functioning provides little scope for exhibition of the specific deviant behaviours required for the diagnosis of autism; it also occurs in individuals with a severe specific developmental disorder of receptive language. Atypical autism thus constitutes a meaningfully separate condition from autism.
- atypical childhood psychosis
- mental retardation with autistic features
Some examples of how a person could actually meet these criteria:
- Fitting the criteria for Asperger’s, and not the criteria for autism, with the exception that the person had delayed language early in life.
- Fitting the criteria for Asperger’s, and not the criteria for autism, with the exception that the person has a lower IQ than the cutoff for Asperger’s.
- Fitting the criteria for Asperger’s, and not the criteria for autism, with the exception that the person had a delay in self-help skills early in life.
- (For the DSM-IV, but not the DSM-IV-TR.) Meeting the social criteria of autism alone, without the other criteria.
- (For the DSM-IV, but not the DSM-IV-TR.) Meeting the language criteria of autism alone, without the other criteria.
- (For the DSM-IV, but not the DSM-IV-TR.) Meeting the repetitive behavior criteria of autism alone, without the other criteria.
- Meeting the social and language criteria for autism, but not meeting the repetitive behavior criteria. (Meeting social and repetitive behavior without language is mostly covered by Asperger’s.)
- Having “a few autistic traits”.
- Seeming autistic, but having another condition going on (such as cerebral palsy or intellectual disability) that makes it hard for a person to do enough things to fulfill the autism criteria.
- Meeting the criteria for some other kind of autism, but not quite enough (in number) of the criteria.
- Meeting the criteria solidly in one category, but ambiguously in one or more of the other categories.
- Meeting the criteria, but ambiguously in all categories.
- Meeting the criteria, but meeting them (or some of them) later than the cutoffs for other things.
Every time I see people making broad generalizations about what “PDD-NOS” means, I wonder if they know exactly how varied the people are that the word can be officially applied to. PDD-NOS doesn’t necessarily say anything about “severity” (as most people conceptualize severity). It doesn’t necessarily say anything about language development. It doesn’t necessarily say anything about anything, given the amount of combinations of things it can be used for, legitimately or otherwise, and it’s wrong to make generalizations about “the unique manner in which PDD-NOS kids socialize as opposed to other kids on the spectrum” or “the severity of PDD-NOS as compared to Asperger and autism” etc. Those are meaningless statements.