why Ed Ritvo’s research was ‘inconclusive’

Ed Ritvo is a major figure in autism research. For decades, he and his colleagues explored the anatomy and physiology of children diagnosed with autism. In Understanding the Nature of Autism and Asperger’s Disorder, published in 2006, Ritvo sets out their key findings:

-stepwise rather than smooth, developmental trajectory
-perceptual inconstancy
-delayed language development
-delayed development of relatedness
-delayed maturation of REM sleep
-delayed development of balance system
-multiple differences in brain anatomy and function.

Despite the breadth and detail of their research, many findings were inconclusive because some, but not all, participants showed particular features. Ritvo concluded that new tools, notably gene research, were required before the causes of autism could be identified.

On re-reading Ritvo’s book recently I noticed things I’d overlooked first time around.

1. Bleuler wasn’t an historical figure to Kanner or Asperger

In Chapter 1, Ritvo introduces us to the to the eminent Chester Keefer, Dean of the Boston School of Medicine when Ritvo trained there in the 1950s. Dr Keefer insisted his medical students study the history of a medical condition. Ritvo notes that Leo Kanner, who published his seminal paper ‘Autistic disturbances of affective contact’ in 1943, shared with Keefer “a love for the history of medicine and the wisdom it conveyed. This is why I am sure that Dr Kanner was very familiar with the writings of a famous Swiss psychiatrist, Eugen Bleuler. This is because he borrowed Bleuler’s term “autistic”: to describe the fact that his young patients could not relate emotionally to others.” (p.21). Ritvo makes the same claim for Hans Asperger (p.23).

But Kanner and Asperger wouldn’t have had to go far back in history to borrow Bleuler’s term ‘autistic’. Bleuler, based in Zurich, coined the term ‘autism’ to describe a feature of schizophrenia in his Dementia Praecox, oder Gruppe der Schizophrenien (Dementia Praecox, or the Group of Schizophrenias) published in 1911. His much reprinted Lehrbuch der Psychiatrie (Textbook of Psychiatry) came out in 1916, only five years before Leo Kanner qualified in medicine in Berlin, and 15 years before Asperger qualified in Vienna. In other words, Bleuler was as much of an historical figure to Kanner and Asperger as Chester Keefer would have been for Ritvo. Kanner and Asperger used the term ‘autistic’ in the way it was used in contemporary textbooks. The fact that Ritvo thinks Kanner and Asperger viewed Bleuler as an historical figure implies that he wasn’t aware they were contemporaries.

2. Ritvo’s medical model is incomplete

Ritvo also introduces us to Chester Keefer’s medical model of disease (p.18).

Ritvo is writing for a non-specialist readership, so might have simplified the model. But it omits some important features.

Symptoms: what the patient reports. Signs, in contrast, are features of the condition that can be observed by others. Autism has always been diagnosed on the basis of signs rather than symptoms, but Ritvo doesn’t include signs.

Pathology: what we think of as abnormal or pathological depends on what we think normal is. There is no standard issue human being. Variation between human beings isn’t always pathological. Autistic characteristics aren’t always pathological.

Causes: A particular pathology can be due to one or more causes, but similar symptoms can result from different pathologies. There’s no doubt that everyone with a fever, sore throat and rash has a sore throat, fever and rash. But those symptoms could be caused by smallpox, chicken pox or measles, to name but three. There can be different causes for similar symptoms in different patients. Similarly there can be different causes in different people for autistic characteristics.

3. Turning an adjective into a noun isn’t just a quirk of language

Ritvo comments: “We have a tendency in our language to change adjectives into nouns. Thus, soon after Dr Kanner’s first paper appeared with the adjective “autistic” in the title, it quickly morphed into “autism”: a thing. Now children had autism or were called autistic” (p.21). Ritvo attributes autistic [adjective] turning into autism [noun] to a tendency of language. In fact, it’s a cognitive process known as reification (making into a thing). Here’s how the transformation from ‘autistic’ to ‘autism’ appears to have happened:

Eugen Bleuler used der autismus [noun] as a descriptive shorthand term for one of the characteristics shown by schizophrenic patients. Medicine is replete with shorthand descriptive nouns because physicians observing patients need to make notes quickly.

Let’s say a patient shows dysphasia (difficulty with speech) and alexia (inability to read). You could say that they ‘have’ dysphasia and alexia. But they don’t ‘have’ dysphasia and alexia in the same way as people ‘have’ measles or malaria. Measles and malaria are specific medical conditions with known causes, so the diagnosis tells you what the signs, symptoms and causes are. In contrast, dysphasia and alexia are merely descriptive labels. They could be caused by a stroke, a tumour or traumatic head injury; the labels don’t tell us.

Bleuler coined the term autism as merely a descriptive label. Kanner’s 1943 paper was entitled ‘Autistic disturbances of affective contact’ because Kanner was using autistic [adjective] to highlight similarities between his child patients and one of the features of Bleuler’s schizophrenia (some of Kanner’s patients had previously been given a diagnosis of schizophrenia).

It’s true that by 1956, Kanner and his colleague Leon Eisenberg (Eisenberg & Kanner, 1956) were no longer referring to “autistic [adjective] disturbances of affective contact”, but instead to “infantile autism [noun]”, but that wasn’t due to a tendency in English to change adjectives into nouns. It was because Eisenberg and Kanner felt there was sufficient evidence to support Kanner’s original hypothesis that he had identified a “unique ‘syndrome’, not heretofore reported” (Kanner, 1943 p.242).

That would have been a reasonable conclusion had it not been reached by drastically reducing and broadening the number of “essential common characteristics” exhibited by the children. Kanner had originally described 20 very specific “essential common characteristics” in 11 children – which Kanner’s own observations showed were neither essential nor common. By 1956, 120 children had been diagnosed with Kanner’s syndrome, but some of Kanner’s original ‘essential common characteristics’ had been discarded, and the remaining 15 were collapsed into five. And in the 1970s, Lorna Wing and Judith Gould (Wing & Gould, 1979) screened nearly 1000 children and reduced the number of criteria to three (later known as the Triad of Impairments).

What is autism anyway?
In short, the larger number of children diagnosed, the fewer and broader the diagnostic criteria had become. Or to put it another way, broadening the diagnostic criteria meant that more children qualified for the diagnosis. It’s the equivalent of diagnosing all patients with a fever, sore throat and rash as having ‘fever-sorethroat-rash’ disease even if each patient has a distinctive rash indicating smallpox, chicken pox, or measles. ‘Autism’ or ‘autistic’ as descriptive shorthand labels had been reified into a thing called ‘autism’.

Why does it matter if Ritvo thought Kanner and Asperger saw Bleuler as an historical figure, or that he thought ‘autistic’ had morphed into ’autism’ due to a quirk of language? It matters because our conceptual model of a medical condition affects the way we interpret data about the condition.

‘Autism’ is a broad label. Many different underlying physical variations can result in autistic characteristics (see for example The Biology of the Autistic Syndromes by Gilberg & Coleman). But practitioners are pretty much obliged to use the official (broad) diagnostic criteria for diagnosis or accessing support. So are researchers, if they want to qualify for funding. This means there’s an assumption implicit in their research models, that all the people in an autistic group will have the same cause for their autistic characteristics. Here’s a hypothetical example to illustrate the type of problem that causes (please note this is a made-up experiment and I’ve simplified the representations of the results to illustrate the point)…

Many people diagnosed with autism report being hypersensitive to sensory stimuli (visual, auditory, tactile etc). Let’s say we design a series of experiments to test the hypothesis that autism is caused by sensory hypersensitivity. We might start by comparing auditory sensitivity in an experimental group of 20 people diagnosed with autism, and a control group of 20 typically developing people.

Let’s also say our results show that on average, our autistic group have higher scores for auditory sensitivity than our control group, but the difference isn’t statistically significant. We could represent the mean scores like this:

Furthermore, two members of the autistic group have the lowest auditory sensitivity scores of all participants, and three of the control group have higher scores than the autistic group average.

What do we do with the atypical scores in both groups? If we include them in our data we get an inconclusive outcome, but if we assume they’re due to an experimental artefact, call them ‘outliers’ and ignore them, our average scores will be statistically significantly different.

Alternatively, we could further investigate the variation within both groups, because:
-We might actually have two groups of autistic people – one where auditory hypersensitivity contributed to their autism, and one where it didn’t, or
-Auditory hypersensitivity might vary across the general population and be incidental to a diagnosis of autism.

Our example is a made-up experiment, but similar results have been found in real experiments (Gerrard & Rugg, 2009). Inconclusive findings about x being a cause of autism, are usually interpreted as ‘there is no evidence of x causing autism’ which is further interpreted as ‘x doesn’t cause autism’. Of course absence of evidence isn’t evidence of absence, especially if the absence of evidence is due to groups of people diagnosed with autism being assumed to be homogeneous rather than heterogeneous.

Ritvo pioneered some important research, but progress in much of it stalled solely because of the assumption in the research design that people with autistic characteristics form a homogeneous group. The later genetic studies,that Ritvo was looking forward to, have made it clear that different people can have different causes for their autism.

References

Gerrard, S & Rugg, G (2009). Sensory Impairments and Autism: A Re-Examination of Causal Modelling, Journal of Autism and Developmental Disorders, 39,1449-63.
Gillberg, C & Coleman, M (1992). The Biology of the Autistic Syndromes (2nd edition). Mac Keith Press.
Kanner, L. (1943). Autistic disturbances of affective contact. Nervous Child, 2, 217-250.
Ritvo, E R (2006). Understanding the Nature of Autism and Asperger’s Disorder, Jessica Kingsley Publishers.
Wing, L. & Gould, J. (1979). Severe impairments of social interaction and associated abnormalities in children: Epidemiology and classification, Journal of Autism and Childhood Schizophrenia, 9, 11-29.

a critical look at Kanner’s autism

In this post I want to take a close look at Leo Kanner’s ground-breaking paper ‘Autistic Disturbances of Affective Contact’ and explain why I consider Kanner’s analysis of the children featured in the paper to be critically flawed. I can understand why Kanner came to his conclusions; he was working in the light of knowledge that was available at the time. What concerns me is that his reasoning has been perpetuated in the diagnostic criteria for autism and in autism research. I suggest it’s because of this that 70 years later we are still scratching our heads about what causes autism.

In 1938, a five year-old boy named Don (later identified as Donald Triplett) was referred to Kanner’s clinic. Don’s was the first and most detailed of 11 case studies (eight boys and three girls) featured in Kanner’s paper published in the journal Nervous Child in 1943. Kanner claimed that he had identified a “unique ‘syndrome’, not heretofore reported” (p.242) consisting of “inborn autistic disturbances of affective contact” (p.250). He reviewed the children’s previous diagnoses and then outlined a list of “essential common characteristics” (p.242) that supported his hypothesis.

Previous diagnoses

Previous diagnoses included idiocy, imbecility, deafness or being hard of hearing, and schizophrenia. (At the time, ‘idiot’ and imbecile’ were technical terms; an imbecile was someone with an IQ score between 20 and 49, and an idiot had a score below 20. Anyone with an IQ between 50 and 69 was described as a ‘moron’). Kanner ruled out idiocy and imbecility because all the children had what he described as ‘good cognitive potentialities’ (p.247). He appears to have ruled out hearing difficulties on the grounds that another doctor had observed that one of the children (Virginia) “does not seem to be deaf from gross tests” (p.230). Kanner rejected the diagnosis of schizophrenia because the children had shown their unusual characteristics from birth.

The term ‘autism’ wasn’t invented by Kanner; it had been coined thirty years earlier by Eugen Bleuler, born near Zürich, and a contemporary of Kraepelin and Freud. Bleuler used ‘autism’ to describe the self-absorbed, withdrawn characteristics seen in schizophrenia, another label he came up with to replace Kraepelin’s ‘dementia praecox’. Bleuler’s book Dementia Praecox or the Group of Schizophrenias was published in 1911, ten years before Kanner graduated in Berlin and twenty years before Hans Asperger did so in Vienna, so both of them would have been familiar with the word they used to describe the children in their case studies.

Kanner’s syndrome

Kanner based his conclusion that he had identified a previously undiscovered syndrome on 20 “essential common characteristics” shared by the 11 children. Statistically, it’s highly unlikely that 11 children could show 20 common characteristics without having the same syndrome – until you take a closer look at the characteristics. Here’s the list (Kanner gives a short explanation for each of them);

•inability to relate themselves in the ordinary way to people and to situations from the beginning of life
•extreme autistic aloneness
•failure to assume at any time an anticipatory posture preparatory to being picked up
•ability to speak
•excellent rote memory
•literalness
•personal pronouns are repeated just as heard
•food
•loud noises and moving objects
•monotonously repetitious
•anxiously obsessive desire for sameness
•limitation in the variety of spontaneous activity
•good relation to objects
•masturbatory orgiastic gratification
•relation to people different to that of objects
•good cognitive potentialities
•serious-mindedness
•anxious tenseness
•physically normal
•from highly intelligent families.

What’s interesting about the ‘common’ characteristics is that they are not common to all the children, nor do they all reflect what Kanner describes in his case studies. The second point applies to seven items on the list, which I’ll address in turn.

Ability to speak, excellent rote memory, literalness and personal pronouns are repeated just as heard. Seven of the children had previously been considered deaf or hard of hearing because of their abnormal receptive and/or expressive speech. Three children (Richard, Herbert and Virginia) presented as mute. Richard had once been heard to whisper “good night” and pupils at Virginia’s school claimed she had said ‘chocolate’, ‘marshmallow’, ‘mama’ and ‘baby’ (p.231). There’s no record of Herbert saying anything. Despite speech or language impairments, other children in the group had clear enunciation, sophisticated vocabularies or good sentence structure, and some had specific problems with pronouns. Yet despite this range of differences, Kanner concludes “there is no fundamental difference between the eight speaking children and the three mute children” in terms of “the communicative functions of speech” (p.243).

Food. Six of the children had feeding difficulties as infants (one vomited repeatedly and another was tube-fed). But Kanner interprets these characteristics not as feeding difficulties per se, but in terms of “our patients…anxious to keep the outside world away, indicated this by the refusal of food” and contrasts their behaviour with those of “affect-hungry” children demanding excessive quantities of food when placed in foster-care (p.244).

Failure to assume at any time an anticipatory posture preparatory to being picked up. Kanner notes this in only two specific cases, but says that ‘almost [my emphasis] all the mothers …recalled their astonishment’ at the children’s failure to respond (p.242).

Masturbatory orgiastic gratification. Kanner’s evidence for this is the children’s preoccupation with spinning objects, jumping up and down with glee and rolling and rhythmic movements, despite his records indicating masturbation in only two cases.

Two questions

So, two questions: First, why did Kanner list as “essential common characteristics” characteristics that weren’t common to all the children? Second, why did he interpret some very somatic (bodily) characteristics (feeding, speech, jumping and rolling) in social and sexual terms rather than in terms of feeding, speech and motor movements? The answers, I suggest, lie in the theoretical frameworks that Kanner was using at the time – Kraepelin’s classification of mental disorders, and psychodynamic theory. (Kraepelin’s classification system and the psychodynamic model had both been in use for half a century, so were well-established. Adolf Meyer, who appointed Kanner to his post at Johns Hopkins, had been a keen advocate of both frameworks.)

Why weren’t Kanner’s ‘essential common characteristics’ common to all 11 children?

I mentioned earlier that Kraeplin’s classification system was based on syndromes – patterns of symptoms that tended to co-occur. Two observations about syndromes: First, syndromes are about correlation, not causality. It’s true that symptoms that tend to co-occur are more likely to be causally linked than symptoms that don’t, but all you can deduce from co-occurring symptoms is that the symptoms sometimes co-occur. You can only make deductions about how the symptoms might be causally linked once you know something about what causes them.

Second, although syndromes have consistent core symptoms (if they didn’t they wouldn’t be syndromes), the symptoms shown by individuals tend to vary. So everyone diagnosed with Syndrome Alpha, say, would show the core symptoms A, B and C, but together those people might also show symptoms D to T (making a total of 20 symptoms associated with Syndrome Alpha). Kanner couldn’t tell from a sample of 11 children which symptoms were core ones and which might have appeared by chance. He would no doubt have been interested to hear from clinicians who’d seen cases of any of the symptoms, so he wouldn’t have wanted to miss anything out. Hence he cast his net quite wide. In short, his “essential common characteristics” were characteristics of his proposed syndrome rather than of the individual children.

Why did Kanner interpret somatic abnormalities (feeding, speech and body movements) in social and sexual terms?

I noted in the previous post that psychodynamic theory recognised the link between behaviour and the brain. (Two of the founders of the psychodynamic school, Freud and Jung, had worked with renowned neurologists and Adler had begun his career as an ophthalmologist, so they would have been well aware of the brain-behaviour connection.) Because the brain was involved and the brain is an organ of the body, behavioural drives, like other bodily characteristics, could be inherited. Characteristics were inherited via sexual reproduction, so any characteristics that reduced the chances of sexual reproduction taking place, such as impairments in affect or communication, or atypical sexual behaviour, would be less likely to be passed on to the next generation, would not be ‘normal’ for the species and so could be considered pathological. Psychodynamic theory saw social and sexual behaviour as fundamentally important in normal child development, and impairments in social and sexual drives as being capable of causing problems with feeding, speech and motor control (Kanner cites David Levy and Hilde Bruch, both of whom used a psychodynamic approach, to support his argument). As Kanner says “the outstanding, “pathognomonic”, fundamental disorder is the children’s inability to related themselves in the ordinary way to people and situations…” (p. 242).

Why I see Kanner’s analysis as flawed

I see Kanner’s analysis as flawed because of three assumptions he made. First, that because the individual children’s characteristics overlapped, despite not all the children having all the symptoms, all the children had the same syndrome. Second, that the existence of a syndrome meant that the characteristics of the syndrome must be causally related. Third, the assumption that social and sexual drives are so fundamental that they must be the cause of problems with feeding, speech and motor movements. Although children certainly can refuse to eat or speak because of an underlying issue with affect, knowing what we now know about brain development, it’s highly unlikely that a babe-in-arms would not suckle or that an older child wouldn’t speak for years on end for that reason. Since motor function is implicated in all three behaviours it should at least be considered as a possible cause.

At the time, Kanner’s assumptions weren’t unreasonable, and at the end of his paper, he makes it clear that he’s making assumptions and that there’s uncertainty about how affect could result in the syndrome he proposes. At the time a good deal was known about brain structure and what brain areas controlled what types of behaviour, but brain function was still something of a mystery. In 1943 Karl Lashley was still attempting to find the location of memory, it would be a decade before Crick and Watson unveiled their model of DNA, and two decades before Hubel and Wiesel published their work on cat visual cortex.

In the light of current knowledge about brain function, Kanner’s conclusion that all the children’s unusual behaviors were attributable to an “inability to relate themselves in the ordinary way to people and situations” doesn’t hold water. Despite this, his assumptions have persisted in the diagnostic criteria for autism, and thus in autism research. I suggest the assumption that autism is caused by a fundamental impairment in social interaction has been the main reason why, half a century later, we are still trying to find the causes of autism. In my next post I propose that turning Kanner’s model on its head could break this log-jam.

Reference

Kanner, L. (1943). Autistic disturbances of affective contact. Nervous Child, 2, 217-250.
(pdf available on line)