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.

Wednesday, August 18, 2010

Making autism research history: The Preschool Autism Communication Trial

Some months ago, Jonathan Green and his colleagues simultaneously published (in the Lancet) and presented (at IMFAR 2010) their multi-site RCT of an early autism intervention. In conducting and reporting the Preschool Autism Communication Trial, they have made autism research history. They have done so simply by applying to autistics scientific standards that are well-established in non-autism non-ABA areas. The upshot is an autism early intervention trial whose results are worth serious consideration and which is unprecedented in this respect.

Via the PACT website, you can find the Lancet paper reporting the PACT RCT, the peer-reviewed PACT intervention "manual" (which refers to another, more detailed manual), the PACT RCT protocols, references for related papers including a 2004 pilot RCT, a list of investigators and funders, and so on.

I've previously written about the PACT as an anomaly in autism intervention research. The PACT entails an early autism intervention that was not widely promoted as effective or essential before it was fairly tested. That is a first in the history of autism research. It may also be the largest RCT of any kind of autism intervention ever published (if I'm wrong, I'm sure someone will tell me).

In short the PACT RCT is an internationally-registered multi-site trial of a manualized intervention targeting the parents of preschool (ages 2-5yrs) autistic children. The PACT intervention spans one year and involves 12 twice-monthly 2hr clinic-based sessions followed by 6 monthly sessions. Parents are expected to apply what they learn, in interacting with their autistic child, for half an hour per day.

For the PACT RCT, 152 children who met criteria for the specific diagnosis of autism were randomly assigned to receive either the PACT intervention plus treatment as usual or TAU alone. PACT and TAU children were well-matched at intake across several measures, and finished well-matched in other treatments received. Parents were not as well-matched. A detailed description of the PACT intervention is here.

Dr Green and colleagues were successful both in recruiting an unprecedentedly large number of preschool autistic children for an RCT--in fact, expectations for recruitment were exceeded--and in minimizing drop-outs. In the Lancet, you will find an outstandingly clear CONSORT flowchart of participants as well as an intention to treat analysis and mixed results.

Results favouring the PACT group were mainly in the area of parent-child interaction, as assessed through videos. The PACT group also outperformed the TAU children in parent-reported vocabulary and social measures, results carefully downplayed by Green et al. due to the parents not being blinded to intervention status. Post-treatment-only measures of adaptive behaviour reported by teachers did not differ between groups.

The main measure was the ADOS used as a scale, and here too there was no result. In my view, using the ADOS as the main measure is a major error but an informative one. The ADOS, as used here (awkward tweaks and all), has thresholds only and doesn't work like a scale. And where is the evidence that lower ADOS scores in very young autistic children in themselves lead to better eventual outcomes? On the other hand, the strong design of the PACT RCT is such that it calls into question what exactly the ADOS is assessing--a result which deserves a lot of attention.

Using ADOS thresholds, 27% of the 146 children who completed their assigned treatment had migrated from the specific diagnosis of autism to the lower-threshold "ASD" category, while an additional 6% no longer met criteria for any autistic spectrum diagnosis. No group differences were found. These findings lend perspective to the widely-publicized diagnostic category results from another recent RCT involving a small sample of much younger children receiving more than two years of intervention.

As with all studies, it's possible to list a range of flaws, potential concerns, and caveats. The ADOS is not only wrongly used as a measure, it is incorrectly used to stratify the sample for randomization. The ADI-R is used in a slightly unconventional way, possibly to accommodate children who otherwise would be excluded by its limitations. There was no screening ergo no exclusion for genetic syndromes, which arguably makes the findings more difficult to interpret. There was poor agreement between raters for two of the three parent-child interaction measures, which in my view is fascinating and telling: nonautistic raters are not good at agreeing about what child initiation and shared attention consist of, when a child is autistic. If you look at the Lancet paper, depending on how your brain works, you should rapidly find at least one minor error in the data (I can't help it...).

The PACT intervention itself has questionable aspects. The fundamental idea is sound: train parents to better respond to their autistic children's communication. But the PACT is a rigidly developmental six-step approach based on how nonautistics develop. In addition, and like so many other autism interventions, the PACT imposes extreme rationing of information and materials. Everything is cleared and shut away except a few toys or items. Anything in which autistics regardless manage to show strong interest will be taken away and replaced with something less interesting. What this does to an autistic child's communication and learning is not considered. The PACT explicitly requires every effort to identify and cater to the parents' different ways of learning, but no such consideration is extended to the autistic children.

The above is a not-close-to-complete list of the PACT's strengths, many of them unique, and its weaknesses--which due to its strengths serve as important information for the future of autism intervention research. Because the trial is so strongly designed compared to the rest of the literature, it is that much more important to learn from and build on. This may not serve the interests of various lobby groups or service providers or political leaders or advocates, but it will serve the interests of autistics. Here is a suggestion from Dr Green and colleagues in the Lancet:
These findings suggest that the optimistic results from other studies should be reassessed.
Yes--good experimental design means that you risk not having your biases confirmed. But taking this risk is currently the only demonstrated way to fairly test interventions and treatments, and for this reason, the only way to conduct ethical research.

There is a Lancet editorial about the PACT RCT, written by two NIH scientists. Here is one thing they point out:
Thus, in a field in which minimum study standards have made it difficult to even look for literature to answer what works for autism, this study is an achievement.
Here is another, and they get the last word:
This study furthers the field by setting a new bar for the minimum standards of rigorous methodology needed in trials that have potentially far-reaching service and policy implications.


Green, J., Charman, T., McConachie, H., Aldred, C., Slonims, V., Howlin, P., Le Couteur, A., Leadbitter, K., Hudry, K., & Byford, S. (2010). Parent-mediated communication-focused treatment in children with autism (PACT): a randomised controlled trial The Lancet, 375 (9732), 2152-2160 DOI: 10.1016/S0140-6736(10)60587-9

Spence, S., & Thurm, A. (2010). Testing autism interventions: trials and tribulations The Lancet, 375 (9732), 2124-2125 DOI: 10.1016/S0140-6736(10)60757-X