Thursday, March 29, 2012

Autism and intellectual disability in DSM-5

Earlier this week, I wrote about the recently published study by McPartland, Reichow and Volkmar, looking at the potential impact of the proposed DSM 5 criteria for Autism Spectrum Disorder. There were caveats-a-plenty but the data suggested that autism rates may go down considerably as a result of the renegotiation of diagnostic borders. In fact, a new diagnosis, Social Communication Disorder, has been created to capture all the people who won't now make the ASD cut-off.

In the comments, an important question was raised by Harold Doherty, author of the Autism in New Brunswick blog: What will happen to autistic people with intellectual disability in DSM 5?

Although I didn’t mention it in the original post, this was actually something that McPartland et al looked at in their study.

Harold's concern, which he's been raising for some time, is that the wording of the new criteria will actually (and, in his view, deliberately) exclude people with an intellectual disability.

Under the draft version of DSM 5, in order to receive an ASD diagnosis, a person would have to show:
"persistent deficits in social communication and social interaction across contexts, not accounted for by general developmental delays." 
It's that last part that is the issue for Harold.

The idea, as I interpret it, is to make sure that people getting an ASD diagnosis really are autistic and not merely people who have social difficulties that are a result of developmental delay.

An analogy would be with people who are born deaf or blind; they inevitably have social interaction difficulties but we wouldn't necessarily call them all autistic. In the same way, someone with intellectual disability might struggle in certain social situations because of their poor language and memory skills, but again they wouldn't necessarily be considered to have autism.

Autism is more than just being a little behind in terms of social development. It’s qualitatively different. The challenge is to define those qualities.

This interpretation of the new criteria is entirely consistent with the quotation Harold provides from Cathy Lord, a member of the DSM-5 Neurodevelopmental Work Group:
Catherine Lord… said that the goal was to ensure that autism was not used as a “fallback diagnosis” for children whose primary trait might be, for instance, an intellectual disability or aggression. New York Times, 20 Jan, 2012 
Clearly, the intent is to stop non-autistic people getting an ASD diagnosis. That isn’t the same thing as saying that, if you’re intellectually disabled, you can’t also be autistic.

So much for the intentions. What about the guidelines in practice?

In one of their analyses, McPartland et al. divided people up according to their IQ. Those with IQs below 70 were considered to have “low cognitive ability”, which I think for our purposes we can treat as being synonymous with intellectual disability.

As in the previous post, I’ve plotted the results with kids achieving a DSM-5 ASD diagnosis in blue (ASD+) and those missing out on a diagnosis in red (ASD-).

As we saw last time, a good chunk of the kids failed to meet DSM-5 criteria for ASD. However, kids with intellectual disability were much more likely to be diagnosed with ASD than were those with IQs above 70. This is the opposite of what we’d expect if DSM-5 really was going to selectively exclude the intellectually disabled.

As I discussed before, we need to treat these findings with a good deal of caution. But I can't see any intention to exclude people with intellectual disability, and there's certainly no evidence at this time that this will happen in practice.


McPartland JC, Reichow B, & Volkmar FR (2012). Sensitivity and Specificity of Proposed DSM-5 Diagnostic Criteria for Autism Spectrum Disorder. Journal of the American Academy of Child and Adolescent Psychiatry, 51 (4), 368-83 PMID: 22449643


  1. I'm not sure that the problem is as simple as you are making it out to be.

    McPartland et al did not attempt to apply the "not accounted for by general developmental delays" part of the criteria, so their data is not really applicable here.

    The phrase "general development delays" seems to be a reference to the Intellectual Developmental Disorder or ntellectual or Global Developmental Delay Not Elsewhere Classified.

    Assuming that this is the correct reference, take a careful look at those criteria. Every person who qualifies for an autism diagnosis is going to meet criteria B and C. Thus the only way to differentiate is criteria A.

    So the question is, if you have a person that meet all of the autism criteria but is tested as having an IQ of less than 70, which diagnosis applies?

    Or to put it a different way, how do you quantitatively tell the difference between a person that does badly on an IQ test because their autism gets in the way and a person that does badly because they are intellectually disabled?

    I don't know of any standardized test that distinguish between between the two cases.

    And that ignores the third case - a person who has all of the symptoms of autism and is also intellectually disabled. Which diagnosis applies?

    In general practice, I could see a practitioner looking at the whole person and making a judgement call. But in research, I see anybody who has an tested IQ of less than 70 being systematically excluded from the autism group.

    And if there is one thing that McPartland et al reminds us of, about 65% of people with autism have a tested IQ of less than 70. What happens to this group if they are systematically excluded because their tested IQ is too low?

    1. Thanks MJ. I think I understand where you're coming from, but I'm certain you're wrong in this instance:

      It comes back to the "not accounted for by general developmental delays" part.

      You (and I think Harold, but he can speak for himself) are interpreting that as

      "if you have general developmental delay then this item doesn't count".

      Which of course would mean that nobody with developmental delay could be autistic.

      This, I am quite sure, is a misinterpretation!

      The point is that the diagnostic criteria are looking for something that is qualitatively different to what is found in non-autistic individuals with intellectual disability.

      So, for example, under "Deficits in social-emotional reciprocity", McPartland et al looked at things like:
      * Markedly impaired awareness of others
      * Lack of shared enjoyment or seeking to share own enjoyment
      * Failure to initiate conversation

      These are not things that you tend to observe in non-autistic people with intellectual disability. In other words they are examples of social communication deficits not accounted for by intellectual disability.

      So McPartland et al did apply the "not accounted for by general developmental delay" rule because they were expressly looking for social communication impairments that are not found in non-autistic people with developmental delay.

    2. I've just reinstated a paragraph (underlined) that I deleted just before posting. I thought it was overkill, but I now realise it's critical!

    3. So you are of the opinion that "general developmental delays" is not a specific reference to " Intellectual Developmental Disorder or Intellectual or Global Developmental Delay Not Elsewhere Classified." ?

      I could understand if the language was meant to be "development delays" in general, or other "development delays", but when you put it together it seems like a specific reference.

      But lets assume, for the sake of argument, that you are correct and that the phrase is meant as a reference to other developmental delays, in general.

      You would still have a hard time telling the difference between a young child with certain conditions like mixed expressive/receptive language disorder (I am assuming that is still in the DSM 5) and autism.

      And if you include the upcoming SCD in "developmental delay", the social aspects of autism are no longer unique to autism.

      It seems, at least to me, that that little phrase is going to cause a great deal of problems.

      If Volkmar and others are correct in that the autism criteria in the DSM 5 are an attempt to limit the number of autism cases then intentionally excluding people with ID actually makes a great deal of sense. That one little phrase could cut the number of autism cases in half.

      Although I'm not sure that I buy into the idea that that is the purpose of the DSM 5 autism criteria.

      And, coming from a more historical perspective, what is exactly is the difference supposed to be between a "pervasive developmental delay" (PDD) and a "general developmental delay".

      In the DSM IV, autism is a pervasive developmental delay but in the DSM 5 it excludes general development delays?

      What exactly is the difference between "pervasive" and "general"?

    4. I'm still not getting this across very well!

      OK, so maybe another way to think of it:

      There are three sections, A, B, and C. A and B each have a general description followed by specific items.

      For B, the general description is (paraphrase) "Restricted interests and repetitive behaviour" This is then followed by various examples of restricted interests or repetitive behaviour.

      For A, the general description is (paraphrase) "Social communication deficits not accounted for by developmental delay". This is then followed by various examples of social-communication-deficits-that-are-not-accounted-for-by-developmental-delay.

    5. Hmm, I noticed but I guess I never really paid attention to the fact that the language regarding general development delays only applied to the Social/Communication criteria (Part A).

      That might make a little bit of a difference when it comes to differentiating autism from other conditions.

      But this - "This is then followed by various examples of social-communication-deficits-that-are-not-accounted-for-by-developmental-delay." still doesn't seem right.

      The exact language says that -

      Persistent deficits in social communication and social interaction across contexts, not accounted for by general developmental delays, and manifest by all 3 of the following

      I read this as -

      Persistent deficits in social communication and social interaction across contexts and manifest by all 3 of the following

      which is then modified by -

      not accounted for by general developmental delays

      Or, in short, as all three sub criteria could be met and criteria A would not be fulfilled if the deficits could better be accounted for by a general developmental delay.

      Whereas you are suggesting that it should be -

      Persistent deficits in social communication and social interaction across contexts

      modified by -

      not accounted for by general developmental delays

      and then, as a separate condition -

      manifest by all 3 of the following

      which means that there are deficits in social communication and interaction not acounted for by general development delays AND these three specific sub criteria of social/communication delay are met.

    6. What's troubling me is the phrase 'accounted for'. In your post, Jon, you say:

      "An analogy would be with people who are born deaf or blind; they inevitably have social interaction difficulties but we wouldn't necessarily call them all autistic. In the same way, someone with intellectual disability might struggle in certain social situations because of their poor language and memory skills, but again they wouldn't necessarily be considered to have autism."

      The problem with 'accounts for' is that unless clinicians *know* that an impairment in social interaction, communication or flexible behaviour is caused by deafness, blindness or so-called 'intellectual' disability (whatever that really means) they won't be able to make the judgement call about what accounts for autistic characteristics. If autism exists independently of deafness, blindness or intellectual impairment, since we don't know what causes autistic characteristics, we can't know what 'accounts for' autistic characteristics in deaf, blind or intellectually impaired people.

      Most people diagnosed with an autistic spectrum disorder do have visual, auditory and intellectual impairments. So do those impairments 'account for' their autistic characteristics or are they simply co-morbid with some difficult-to-define qualitative difference?

  2. The CDC just published their latest autism prevelance rates in the US. It's now 1 in 88. That was predicted by Allen Francis, the editor of DSM-IV (1994) who has stated that the field trials of DSM-IV failed to predict the false epidemics of autism, attentional disorders and bi-polar disorder.

    Plomins group in the UK has tested thousands of twin pairs recruited from the Twins Early Development Study registry and found that 10% of all general population children have what they called severe autistic traits. Milder autistic-like traits would penetrate even deeper in to the general population.

    The rubber band keeps stretching until it will break. That's what DSM5 is designed to do, make an autism diagnosis much more restrictive,what Volkmar has called 'stopping the epidemic in its tracks'.

    It doesn't do any good for the child or for research when psychologists like Tony Attwood interview a perfectly normal child who might be shy and unassuming and have no interest in sports and instinctively reaches for his ever ready rubber 'Asperger Syndrome' stamp.

    In DSM-IV the diagnostic criteria for the severest sub-category, Autistic Disorder, consists of sixteen isolated symptoms none of which is specific to autism suggesting that even in severe cases diagnostic criteria is ambigous and subjective at best.

    Psychologists and child psychiatrists have failed the parents and autism, however, it is defined should come uinder the domain of the medical specialties. Until then all the debate is as Faulkner said 'Full of sound and fury signifying nothing'.

    1. RAJ, I'm not sure if you've spent much time around kids with Aspergers, but I assure you that "..shy and unassuming and have no interests in sports" is a complete misrepresentation of the daily struggles those with Aspergers negotiate. My son, who at age three is suspected Aspie but yet to be confirmed due to his young age, will meet all DSM V criteria.

  3. Where is the prevelance rates for autism headed? Cox et al (2005) in a large study of nearly 6,000 particpants. Social phobia is common in the general population and 26% of women and 19% of men in the study describe themselves as being very shy when growing up.

    Stein et al (2001) found that people with generalized social phobia had a first degree relative who scored higher on measures of trait anxiety and social anxiety and concluded that social anxiety was familial in part.

    In the baby sibs studies in the US researchers have reported that the younger sibs of autistic children who were recruited when the mother was pregnant had high rates of autism at 18 to 24 months of age. Many of the affected baby sibs lost their dagnosis withen a year or two.

    Perfectly consistent with familial social phobia. Given the massive broadening of the concept of autism and based on the Cox study we could easily be headed towards an eventual prevelance rate of 1/5.

    It should also be noted that the prevelance of the severest sub-category Autisitc Disorder hasn't changed much over time about 0.2%.

    Has psychiatry psycho pathologized common, normal human characteristic traits that exists in about 20% of the general population?

    1. "Many of the affected baby sibs lost their dagnosis withen a year or two."

      Was that in the baby sibs study?

  4. MJ:

    Volkmar has stated, as reported in Yale Daily News:

    "In its next manual on mental disorders, the American Psychiatric Association plans to issue a single set of diagnostic criteria that will merge the four types of disorders on the autism spectrum, which include autism and Asperger syndrome. Although no current patient will be affected by the new rules, research by Yale Child Study Center Director Fred Volkmar suggests that the revision may disqualify a large number of intellectually disabled patients from receiving a diagnosis of autism spectrum disorder in the future."

    The obvious exclusionary language of Mandatory Criterion A of the new Autism Spectrum Disorder in the DSM5 means exactly what it says according to Volkmar. The attempt to reduce the numbers of autism diagnoses is targeting the intellectually disabled for exclusion from autism diagnoses in the DSM5 era.

  5. DSM is the North American manual, but the equally widely used diagnostic manual is the World Health Organizations (WHO) ICD manual (International Classification of Diseases). In 1994 the working groups for autism, DSM-IV (1994) and ICD-10 (1994), worked closely together to establish the same autism diagnostic criteria for both widely accepted manuals. Not only are there problems with the DSM5 working groups approach, but there is also a dispute also between the DSM5 and ICD11 working groups for autism that suggest conceptual differences that may not be easily resolved between the groups before the 2013 deadline for publishing both diagnostic manuals.

    Sir Michael Rutter is in charge of the ICD11 working group on autism and has had this to say about the different approaches between the working groups which are supposed to be in agreement with new diagnostic criteria. Rutter, a past European editor of the Journal of Autism and Developmental Disorders agrees with Fred Volkmar, current editor of the Journal of Autism and Developmental Disorders, on the DSM5 working groups approach:

    'At the moment there are important differences between proposals for DSM-5 and ICD-11. For the most part, there is broad agreement on the overall concepts but there are difficulties with respect to the details. That arises most especially because the DSM-5 starts with dealing with research criteria before considering the concepts and WHO does it the opposite way round. That is to say, the starting point with WHO is the clinical conceptualization and the clinical criteria. At a later point, of course, research criteria have to be developed but that comes secondarily. In my view, that is the most appropriate way round'.

    ‘The current proposals for DSM-5 would make a huge difference to prevalence estimates of ASD. That is because the field trials analyses undertaken by Fred Volkmar and his research group have shown that the majority of higher functioning cases (such as with Asperger’s syndrome) would be excluded. There is a paper on this that is currently 'in press' in the Journal of the American Academy of Child and Adolescent Psychiatry. I hope that these findings will lead to a change of proposal for DSM-V’.

    ‘’ The increase in the prevalence figures for ASD are certainly due in part to improved clinical sensitivity and ascertainment and partly the broadening of the diagnostic concept. However, whether, in addition, there has been a true rise in incidence remains uncertain. I think it is important to keep an open mind on this because, if there has been a true rise, that would have implications for some non-genetic factor playing a role, probably a contributory role, in causation’.

  6. This is an interesting discussion!

    I am an experienced school psychologist who works with children, teens, and young adults in a school-based program for those who have significant cognitive delays. About half of the students have autism spectrum disorders. There are important differences between the students who are intellectually disabled and those who have autism in addition to the intellectual disability.

    I also work at a regular high school. I know that many higher-functioning young people diagnosed with Asperger Syndrome who would not have made good progress in school and in other areas if they had not been identified or provided supports.

    In my opinion, we need to have better tools for assessing cognitive/intellectual functioning among those who perform at the "70 or below" level on traditional IQ tests. I use cross-battery assessments when possible in order to get a better sense of the range of strengths and areas of need, and work collaboratively with an occupational therapist and a speech/language pathologist when I evaluate a student.

    I have recently noticed that many students I work with can respond to informal assessments using apps I've gathered for this purpose on my iPad. Perhaps the test publishers will work on some cognitive assessment applications that will shed more light on the functioning of students who have characteristics of autism and intellectual disability.

  7. Can someone tell me how to differentiate between intellectual disability and autism? If you know your child is very smart but he gets a low IQ ( below 70), how do you dispute that?