Tuesday, August 31, 2010

Are you high or low functioning? Examples from autism research

If you are autistic and ever venture or are pushed into public, a near-certainty is that you will publicly be ranked and classified by total strangers.

For example, you will be assigned to the "high end" or the "low end" of the autistic spectrum, according to whether you are claimed to have a good or bad outcome (I've been claimed to have both). Non-political observers may notice how ethically and scientifically problematic this is, but there are few discussions, formal or informal, in which autistics aren't automatically assigned "high-functioning" and "low-functioning" rankings as definitive and permanent aspects of ourselves: there are LFAs and then there are HFAs.

If the whole area of autism were not so politicized, it might have long been seen as important to check the scientific basis for these ubiquitous rankings. It might even be seen as an ethical obligation. It might be noticed that there is something wrong with discarding and therefore dishonouring the contributions to research made by the countless autistic children and adults who have been recruited as participants in autism research, and without whom there would be no autism research at all.

I've never been impressed by autism politics, on whatever "side," so I'll start with some basic information about levels of functioning as reported in autism research, then provide several examples pulled from some of the numerous papers I've recently looked at.

What does level of functioning mean in autism research?

In autism research, autistics' level of functioning is most often judged according to scores on specific tests of IQ (e.g., Wechsler) or developmental level (Mullen, Bayley, sometimes the Vineland) at a specific time.

The reported threshold dividing "high" from "low" functioning ranges from 50 to 90--at least in papers I've read so far; the actual range might be even greater. Those are IQ or IQ-type scores with a mean of 100 and a standard deviation of 15. So the threshold, the line dividing "high" from "low" functioning in autism research, is almost three SDs wide. Fall into that impressive span, and you may be high or you may be low functioning, depending on who you ask.

If 90 is the threshold, then about 25% of the entire population (autistic, nonautistic, everyone) is low-functioning. If the more common threshold of 85 is chosen, then about 16% of everyone is low-functioning.

70 is the threshold often considered to be standard even if in reality, if you read the literature, the threshold varies dramatically. But there are different tests and within commonly-used tests there are different ways to set a threshold, even when the threshold is numerically set at 70.

With this in mind, here are some examples.

Example 1

In Farley et al. (2010) the threshold is indeed 70 and autistics with lower baseline (circa age 8yrs) IQs were excluded. As the authors write, "all participants had baseline IQs in the nonimpaired range."

In fact the full-scale baseline IQs of autistics deemed to meet the 70 threshold, and included as participants, range down to 36. An IQ of 36 is near the current threshold for severe intellectual disability. An IQ of 36 (if you were under age ~4yrs) would exclude you from Ivar Lovaas' famous ABA study--you are too low-functioning.

But in different circumstances, which are specified by Farley et al., a full-scale IQ of 36 can also be considered to grossly underestimate your abilities and to put you in a study of participants who would widely be ranked as high-functioning.

Example 2

Klin et al. (2007) is another study where the autistic participants (ages 7-18yrs) are all considered high-functioning and the threshold is 70. In one of two samples, verbal, performance, and full-scale IQs run from 52 to 150. Then there are Vineland scores. While Vineland is a test of adaptive behavior, in autism research Vineland scores can also be used as measures of intelligence ergo level of functioning.

Vineland composite scores in this sample range down to 25. Two of the Vineland domain scores range down to 20. In a recent population-based study (ages 9-14yrs), an assigned Vineland score of 19 was used to represent profound intellectual disability. But in Klin et al., you can have a Vineland composite score of 25, or Vineland domain scores of 20, and you are high-functioning. You are in the same category as someone with a verbal IQ of 150.

Example 3

In Akshoomoff et al. (2004), there is also a threshold of 70, but autistics falling on either side of this threshold are included then divided into lower and higher functioning groups. Performance IQ scores in the lower-functioning group range up to 128. That is not only higher than the individual scores of the entire higher-functioning group, it is higher than all but ~3% of the entire population. If a PIQ of 128 ranks you as low-functioning, as it does in Akshoomoff et al., then almost everyone is low-functioning.

Example 4

In view of the above it might seem wise to abandon the 70 threshold and try something completely different. Annaz et al. (2009) created high-functioning and low-functioning autism groups (ages 5-11yrs) by incorrectly using the CARS (Childhood Autism Rating Scale), which is supposed to be a measure of autism "severity." This study features two measures of intelligence, one verbal (British Picture Vocabulary Scale, a verbal IQ equivalent) and one non-verbal (a subtest from the British Ability Scales).

One result is that you can have a verbal IQ of 62 and be classified as high-functioning, and a verbal IQ of 111 and be classified as low-functioning.

The non-verbal measure is reported in age-equivalents only, but the two autistic groups are remarkably well-matched on age. And the mean non-verbal age equivalents are both (1) the same for the two autistic groups, and (2) very nearly the same as mean chronological age, again for the two autistic groups.

In other words, another result is that both high- and low-functioning autistics here represent groups whose mean measured non-verbal intelligence is the same as the general population mean, and of course vice-versa. Setting aside possible differences in distribution, now everyone is both high- and low-functioning.

Conditional examples 5 and 6

This is a bit of a digression, but if you adhere to the common political or ideological prejudice that "Kanner's autism" is "classical autism" is "low-functioning autism" you are then required to achieve an IQ of over 140 (from Kanner's original 11) or 150 (from Kanner's 1956 follow-up) to be ranked as high-functioning. That means you have to be better than the 99th percentile.

Now what?

The above doesn't nearly convey the arbitrariness in the existing autism literature. As I wrote, I've provided just a bunch of examples, among many others, you will find if you read a lot of papers. Also, I've left out entire major areas, like changes over time and results from deliberate comparisons between different tests of intelligence.

While this was not intentional, the examples above might be construed as exploiting the atypically high variability characterizing individual autistics and in addition characterizing autistics as a group. Then the question is whether it serves the interests of autistics, and whether it advances autism research, to diminish, misrepresent, trivialize, denigrate, obscure, or deny this characteristic variability.

And as usual, the above can be verified by reading the existing autism literature. If there are any factual errors, as is always possible, please let me know.

Futher reading

The late Ivar Lovaas expressed his views about levels of functioning in autism in one of the major ABA manuals; this is quoted here. From a different point of view, this article concisely applies ethical consideration to the issue of level of functioning, among others. In autism politics, the dimension of autism "severity" and the different dimension of "level of functioning" are often wrongly confused or conflated. You can find science-based information about autism "severity" here and here.


Akshoomoff N, Lord C, Lincoln AJ, Courchesne RY, Carper RA, Townsend J, & Courchesne E (2004). Outcome classification of preschool children with autism spectrum disorders using MRI brain measures. Journal of the American Academy of Child and Adolescent Psychiatry, 43 (3), 349-57 PMID: 15076269

Annaz D, Karmiloff-Smith A, Johnson MH, & Thomas MS (2009). A cross-syndrome study of the development of holistic face recognition in children with autism, Down syndrome, and Williams syndrome. Journal of experimental child psychology, 102 (4), 456-86 PMID: 19193384

Farley MA, McMahon WM, Fombonne E, Jenson WR, Miller J, Gardner M, Block H, Pingree CB, Ritvo ER, Ritvo RA, & Coon H (2009). Twenty-year outcome for individuals with autism and average or near-average cognitive abilities. Autism research : official journal of the International Society for Autism Research, 2 (2), 109-18 PMID: 19455645

Klin A, Saulnier CA, Sparrow SS, Cicchetti DV, Volkmar FR, & Lord C (2007). Social and communication abilities and disabilities in higher functioning individuals with autism spectrum disorders: the Vineland and the ADOS. Journal of autism and developmental disorders, 37 (4), 748-59 PMID: 17146708

Postscript: This post has been included in the 40th edition of Scientia Pro Publica.


MalchowMama said...

Another thought-provoking article, Michelle, thank you. I can't speak to how autism severity or level of functioning is measured in research (as you have just done), but in my experience laypersons make these determinations in much the same way an American politician once famously defined pornography: they just "know it when they see it." If a person appears to be unresponsive and uncommunicative, or (God forbid) is upset about something, they are "low-functioning". If they are quiet and respond to instruction, they have "mild autism". It's ridiculous.

Here is one way I could describe my son Sam, who will be 4 in 3 weeks: doubly incontinent, has no language, does not play directly with other kids in his kindergarten, avoids eye contact, eats only a few foods, cannot follow instructions, cannot sit still for long.

Here is another accurate description of Sam: very affectionate with people he knows well, makes long eye contact with his mother, happy, smiles often, has never had a tantrum and rarely cries, enjoys rough-housing with his brother, enjoys singing songs from his favourite movies, loves being outdoors and riding our tandem bike.

One description makes him sound like he has "severe" autism and is "low-functioning", the other makes him sound "mild" and "high-functioning". As you have pointed out, one of the primary features of autism is the wide varience in skills and abilitites a person might have and how much that changes over time and from day to day. Many people think it is just "obvious" that a person is low or high functioning; thank you for continuing to show why this is inaccurate.

Michelle Dawson said...

Thanks for the comment. I didn't mention it in the post, but I've been publicly ranked as a "mid-level autistic," among many other rankings and classifications.

I think someone should write a paper documenting *all* the ways in which autistics have been, and currently are, ranked and classified. It would be a long paper. Maybe a book.

Usethebrains Godgiveyou said...

Also, the IQ is not supposedly fluid--although my son went from 79 at age 4 to whatever he is now. I imagined it has doubled.

This makes sense, as the IQ tests were presented to him verbally at that age, when his understanding of language was still shaky.

I wonder if the Peabody picture vocabulary test, which does measures IQ, would lead to higher scores among younger autists with language barriers.

Thank you for exposing this incongruity among studies.

Michelle Dawson said...

In response to r.b., here's a quote I didn't use from Farley et al. (2009; see the original post to get the full cite):

"Over half of the sample had large gains or losses of cognitive ability of greater than 1 standard deviation."

As I wrote, I didn't even touch on the issue of intelligence scores changing over time. And large changes in measured intelligence over time at the individual level are well-documented in autism research.

Jennie said...

Hi Michelle,

That was a great post. I have read many studies concerning autism as I have come across them recently, and I am always somewhat confused when I read "high-functioning" or HFA. I tend to go right to the section to try and comprehend how they based that assessment of individuals.

I try to avoid any type of label of that type because I believe that every person is high-functioning in some aspects and low-functioning in others. My daughter is now 5 and was diagnosed with autistic disorder two years ago. To some, she may seem low-functioning because she has not yet mastered toileting and some general things such as dressing and hairbrushing. To others, she is incredibly intelligent, genuine, and insightful. She is considered to be on the same academic level as her Kindergarten peers by the school district.

In instances where individuals are classified in studies by a certain measure, would it not be best to simply state that only individuals with autism with a score of X were used versus placing a high- or low-functioning label on that specific set of standards?


Michelle Dawson said...

In response to Jennie, thanks!

I think there are two choices for researchers in any given study:

1. Use the terms "high" and "low" functioning. In this case, you need to do at least two things. You need to provide your criteria: which instrument(s) at which age(s) with which threshold(s). Also you need to provide a science- and ethics-based rationale for your criteria. And I would really like to see one.


2. Trust your data to describe your sample. Among other potential advantages, this plausibly could reduce biases that may be harmful to autistics and an obstacle to the progress of autism research.

In my view, the 2nd choice is worth trying.

farmwifetwo said...

I appreciate your comments on the difference btwn severity and functioning.

My nearly 9yr old can dress himself, feed himself, play on the computer independantly at age appropriate sites, Nintendo - age appropriate, read Gr 4, spelling same. Friendly, social, loves other children, going to the playground, we're off to the Great Wolf Lodge and it's waterpark shortly, loves the rides at the fall fairs, takes swimming lessons.

Sounds like a NT child doesn't it??

No, it's a child with severe autism. One that is caregiver toilet trained, one who's expressive language is coming but still about a 2/3yr old level, one who's social skills are very poor at best, one who's IQ test last fall said he was in the 60's, one who still cannot drink from an open cup and uses a straw, one that runs....

Which is why I wonder at the fight to add ID to the autism dx. Everyone on our team ignores his IQ and he's taught - parent's, school, swimming etc. We currently have 2 dx's on our IPRC - autism and developmental delay... both are valid at this time. Why change it?? Should he not be given the chance to go to University even if he's severely autistic with support? Those in "Autism and the myth of the person alone" many of them are/were.

I'd dx mine "high functioning (ability to learn), severely autistic" - if someone ever asked me.

Barbara said...

Michelle, the terms 'low' and 'high' functioning autism are more common in North America than they are in the UK. Here, we stratify on 'learning difficulties' which can be from severe and profound to mild. But there is a separate category for autism. The 'learning difficulties' stratification is for educational purposes and is based on the movable feasts you mention, 'IQ' and 'functioning', but mainly involves what you call intellectual retardation (I think), and we call intellectual impairment. So we are far more used to autism itself not being conflated with IQ (as denoted in all criteria - nothing to do with IQ, but maybe cognitive function which is a whole different ball game). SPLD can cover any number of learning problems. The distinctions between 'high' and 'low' functioning as used by many positivist scientists, are, as you say, arbitrary and totally dependent on instrumentation that can account both for autistic intelligence and typical intelligence. So far, there don't seem to be any such tests.

Faults lie with the loose definitions and the inadequacy of the term 'IQ' and the assumption that it's static.It means nothing. Intellectual capacity is in flux according to the demands of the test, maturation and experience, and is always situated. My own IQ (and I'm mostly NT although epileptic) has always varied and still varies by 4 standard deviations albeit at the upper end, where IQ scores are notoriously completely unreliable. IQ is not a state, it's a construct, which has far too many variables to be meaningful.

As for 'functioning', surely that can only be determined contextually? It's also completely dependent on what the individual describes. It's never set in stone across all situations. The Leekam et al (2007)paper found that sensory processing issues were identical in severity and intensity in those classed as 'low functioning' and those classed as 'high functioning'. If that's replicated, it will say a lot about what are the core characteristics of autism.

We need to lose this 'IQ' stratification of autism. It's an entity. As is intellectual impairment. But these things are different.

I'd argue with you over what you say about Kanner's studies as I don't believe this can be shoe-horned in to this argument. Kanner was very specific in saying that all the children he saw showed high cognitive potential (mythology has overtaken this very important statement, as has the fact that only one of the initial cohort was totally non-verbal, and he had a good and productive outcome, although Kanner doesn't rank him, Herbert, as such. Kanner's issue was socio-cultural. It was that if you institutionalised these children, and drugged or shocked them or whatever, their outcome would be poor. His imperative was to save these children from losing their cognitive potential by placing them in institutions. Also, you start by discussing final outcomes, and then move on to discussing tests on newly-recruited samples in scientific tests. These are two completely different things, I think. But please do argue with me.

Not all arguments are scientific. Some are socially-constructed and therefore a million times more complex. What we now call 'classic autism' was never defined by Kanner. What we call 'Asperger's Syndrome' was never defined by Asperger. One of his FOUR children was intellectually impaired. Another was deprived of oxygen at birth, which Asperger referred to as an 'organic' problem, and not 'true' autism. So only half of the children he described almost poorly match the criteria for AS.

It's an interesting post you've made. Thank you. I learn from you so much more than I learn from my PhD studies.

Michelle Dawson said...

(I deleted my previous message and am re-posting it to fix some unclear language; long day, more apologies...)

Apologies to Barbara whose comment for no reason got stuck in the new Blogger spam trap. I've just figured out *where* the Blogger spam trap is (there didn't used to be one) and how to rescue real comments from it. Sorry again.

I'm just going to bring up one thing, because I haven't seen it discussed much--it seems non-controversial.

So far as I can tell (again, happy to be corrected if I'm wrong) the proposed DSM-5 will no longer divide up intellectual disability (DSM-IV "mental retardation") into the IQ-based divisions of mild, moderate, severe, and profound.

There have been various IQ-based divisions within "mental deficiency" (DSM-I) or "mental retardation" (the rest of the DSMs) in every DSM, back to the first. The DSM-5 proposes that there should be no such IQ-based divisions (now within "intellectual disability") at all.

You can find this proposed change here (you might want to look at this too).

Anonymous said...

Michelle, thanks for this interesting discussion. Makes quite clear that whatever "functioning" means, even the conventional criteria (eg. IQ) cause confusion.

@ Farmwifetwo: I can relate to your son's experience of different ability levels in different areas, although mine are different from your son's (I have a high IQ and yet severe sensory issues, for example). Makes quite clear that autistics' individual abilities should matter rathert than a standard score of "functioning level" or "severity".

Michelle Dawson said...

Thanks Astrid.

Another thing I didn't mention in my post is that there are two papers published 3 years apart that have exactly the same title:

"A follow-up study of high-functioning autistic children."

The two papers report completely different studies and have no overlapping authors. And as you might guess, they use different criteria for "high-functioning." Neither uses a numerical threshold of 70.

Bryan said...

Here is the criteria for how "functioning" I or anyone else on the spectrum is: How easy is it for me to get laid? Everything else is just gravy, after all. Since it's pretty easy for me, having a loving and willing wife, I'd say I'm high functioning.