The Autism Research Center is headed by the dashing Simon Baron-Cohen, also one of the authors on the paper. He's probably the world's best-known autism researcher, and the author of some excellent books on the subject including the classic Mindblindness and The Essential Difference. Mindblindness, in particular, probably deserves a lot of the credit for interesting a generation of psychologists in autism. A big cheese, in other words. Surely his greatest achievement, however, is being Borat's cousin.
Baron-Cohen is famous for his theory that the characteristic features of autism are exaggerated versions of the allegedly characteristic features of male, as opposed to female, cognition. Namely, autistic people have difficulties understanding the emotions and behaviour of other people ("empathizing"), but may show excellent rote memory and understanding of abstract, mathematical or mechanical systems ("systematizing"). He and his colleagues have also hypothesised that an excess of the well-known masculinizing hormone testosterone, could be responsible for the hyper-male brains of autistics, just as testosterone is responsible for the development of masculine traits in boys. Amongst other things this would explain why rates of diagnosed autistic spectrum disorders are several times higher in boys than in girls.
Now, this is one of those wide-ranging theories which serves to drive research, rather than strictly following from the evidence. It's a bold idea, but there is, at the moment, not enough data to confirm or reject this idea. The simple view that testosterone = maleness = autism is almost certainly wrong, but it's a neat theory, there's clearly something to it, and, as one of the commentators on the paper puts it
To date, no theory of autism has provided such a connecting thread linking etiology, neuropsychology and neural bases of autism.
The headline finding was that fetal testosterone (fT) levels were correlated with later "autistic traits", as judged by the mothers, who filled out questionaires about their kid's behaviour at the age of about 8. Here's a nice plot showing the correlation. The vertical axis, "AQ-child total", is the parent's total reported score on the "Autism Quotient" questionaire. Higher scores are meant to indicate autism-like traits (although see below). You'll also notice that fT levels are much higher in the boy fetuses than in the girl fetuses - not surprisingly. That's it - a statistically significant association, but there is still a lot of scatter on the plot. The correlation was still significant if the very high-scoring children were ignored. A similar pattern emerged using a different autism rating scale, but was less significant - probably because many scores were very low.
So, this was a perfectly decent study with an interesting result, but it's only a correlation, and not an especially strong one. How did this get written up? New research brings autism screening closer to reality puffed the Guardian's front page! They suggested that measuring fetal testosterone levels might be a way of testing for autism pre-natally, thus sparking off an entirely formulaic debate about the ethics of selective abortion, the usual denunciations of "eugenics", etc. Long story short - Catholics are against it, the National Autistic Society say it's a dilemma, while a family doctor on Comment is Free is unsure about the "test" because she can't read the article: she doesn't have access to the journal.Lest it be said that the ethical debate is important in itself, even if the details of the testosterone-based screening test might be inaccurate, bear in mind that "testing for autism" is likely to raise unique issues. Are we talking about a test which could distinguish "low-functioning autism" - which can leave children unable to lead anything like a normal life - from "high-functioning autism", sometimes associated with incredible intellectual achievement? Would the test distinguish classical high-functioning autism from Asperger's? When and if a test is developed, these will be crucial questions. You cannot simply speculate about "a test for autism" in the abstract.
Anyway, after a few days of this nonsense Baron-Cohen rightly protested that the paper had nothing to do with prenatal testing, and that such testing isn't on the horizon yet.
The new research was not about autism screening; the new research has not discovered that a high level of testosterone in prenatal tests is an indicator of autism; autism spectrum disorder has not been linked to high levels of testosterone in the womb; and tests (of autism) in the womb do not allow termination of pregnancies.Most importantly, there were no autistic kids in the study - all of the children were "normal", although some were rated highly on the autism measures. Moreover, as the plot above shows, any testosterone-based screening test would be very inaccurate. Which is why no experts proposed one.
Just like last time. Back in 2007 the Observer (the Sunday version of the Guardian) ran a front-page article about Simon Baron-Cohen's work on the epidemiology of autism. They said that he'd found that autism rates in Britain were "surging"; they probably aren't, and Baron-Cohen's data didn't show that they were, but despite this the Observer took weeks to clarify the issue (for details of the saga, see Bad Science.) In both cases, some important research about autism from Cambridge ended up on the front page of the newspaper, but the debate which followed completely missed the real point. It would have been better for all concerned if the research had never caught the attention of journalists at all.
The actual study in this case is very interesting, as are the three academic commentaries and a response from the authors published alongside it. I can't cover all of the nuances of the debate, but some of the points of interest include: the question of whether the Autism Quotient (AQ) questionaire actually measures autistic behaviours, or just male behaviours; the point that it may be testosterone present in baby boys shortly after birth, not in the womb, which is most important; and the interesting case of children suffering from Congenital Adrenal Hyperplasia, a genetic disorder leading to excessive testosterone levels; Baron-Cohen et. al. suggest that girls with this disorder show some autism-like traits, but this is controversial. Clearly, this is a crucial point.
Overall, while it's too soon to pass judgement on the extreme male brain theory or the testosterone hypothesis, both must be taken seriously. As for autism prenatal testing, I suspect that this will only come when more of the genetic causes of autism are identified. There is no single "gene for autism"; currently a couple of genes responsible for a small % of autism cases are known: CNTNAP2, for example.
Once we have a good understanding of the many genes which can lead to the many different forms of autistic-spectrum disorders, genetic testing for autism will be possible; I doubt that testosterone levels or anything else will serve as a non-genetic marker, because autism almost certainly has many different causes, and many different associated biochemical abnormalities. Maybe I'm wrong, but even so, if you're worried about hypothetical people aborting hypothetical autistic fetuses, you don't have to worry quite yet. Actual children are dying in Zimbabwe - worry about them.
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Bonnie Auyeung, Simon Baron-Cohen, Emma Ashwin, Rebecca Knickmeyer, Kevin Taylor, Gerald Hackett (2009). Fetal testosterone and autistic traits British Journal of Psychology, 100 (1), 1-22 DOI: 10.1348/000712608X311731
14 comments:
Great post!
I'm not even convinced that there IS a single condition of "autism". I rather suspect that, as we learn more, we will find that what we're now calling autism is actually a range of possibly-related conditions with similar manifestations.
It should also be noted that there seems to be a far greater rate of underdiagnosis among girls and women than among boys and men, in large part because most information about autism is based on male autistics, with little research based on female autistics. Males and females differ among autistics just as they do among the neurologically typical.
ranka: Neither am I, in fact I'm sure there isn't (but then there is no single condition of depression or bipolar either - or, indeed, breast cancer. These are all umbrella terms.)
About underdiagnosis, I don't much about that. I suppose there must be a reason why girls are underdiagnosd, if they are. Perhaps they manage to cope better, for whatever reason?
I don't have full-text access to the journal, but presumably the authors ran the correlation separately for males and females?
It looks to me like that correlation is driven largely by the fact that boys have both higher fetal testosterone and higher autistic quotients than girls. Certainly if you looked at the girls alone I doubt you'd have a significant trend, although there might be something there in the boys.
The trashcan of autism history is littered with discredited single cause theories of autism etiology( refrigerator mothers, vaccines and now extreme male traits).
They all fall apart when they can't even begin to explain all the diverse, heterogenous and non specific findings whether genetic, environmental or even neuropathological findings.
The hypothesis is partly based on trying to explain the high male female ratio. An epidemoilogical survy that included over 400,000 cass taken from a Chinese leprosy register reported a 3:1 male feml ratio. Could high fetal tetesterone levelsbe a cause of leproys? Peraps, but only if you believe that exposure to myobactrium leprosy is not the cause of leprosy.
None of the children in Baron-Cohens study ever carried a diagnosis of any subtype of 'autism'.
We are left to ascribing 'autistic traits' to high levels of fetal tetesterone and given the ambiguity of what defines an 'autistic trait' at best, if the study is ever replicated high fetal tetesterone may be associated with a small genetic risk for 'autism'.
Alway be skeptical whenever a new theory of autism suggests a singl cause theory.
Daniel: Yeah they did do that and the correlation held in both boys and girls seperately. Which is good, because running a correlation on data from two groups who differ on some variable is a deadly sin of stats...
RAJ: Yep. Although to be fair I don't think Baron-Cohen is proposing that testosterone is THE cause of autism. Given the spread of this data it obviously isn't...
It needs to be pointed out (again) that none of the subjects in this study had autism. They had different levels of traits that if they had reached a clinical level would, might, maybe constitute autism, but none of the subjects had traits to that degree.
I haven’t read this paper yet, but I did hear SBC give a talk about this research (last fall), and the females were tested separately from the males and the correlation did hold for both separately.
I did mention to him my hypothesis of “theory of mind” vs “theory of reality” as being the trade-off and he said he liked that better conceptually (but that was before reading my detailed discussion of it, so he may have just been being polite). I have since published a brief discussion of it on my blog.
http://daedalus2u.blogspot.com/2008/10/theory-of-mind-vs-theory-of-reality.html
The hypersystematizing hypothesis has some problems because systematization regarding communication abilities is not found at elevated levels in autism (except perhaps for hyperlexia, but that is a very narrow type of communication).
Testosterone synthesis is regulated by NO, which inhibits the enzyme that is the rate limiting step in testosterone synthesis. Low NO results in higher testosterone, in both males and females; high NO results in lower testosterone in both males and females.
Testosterone and estrogen in the brain lower and raise NO levels respectively. I have some links to papers in my blog.
This result is completely consistent with my low NO hypothesis of autism and autism-like disorders.
Any type of metabolic stress leads to low NO which leads to what I call “autism-like” disorders, which I consider things like Rett Syndrome to be. What I consider to be “true” autism depends on low NO in utero where the characteristic neuroanatomy forms. There is a continuous continuum along the autism spectrum, with some movement at any stage of life (depending on the NO level and the degree of neuronal plasticity).
Low NO is the final common pathway in autism and autism-like disorders.
I disagree with the quote
” To date, no theory of autism has provided such a connecting thread linking etiology, neuropsychology and neural bases of autism”.
The low NO theory of autism does connect all of those things and also connects the physical physiology, the oxidative stress, the resolution of autism symptoms with fever, the exacerbation of autism symptoms with stress and every other symptom of autism that I have been able to find reference to in the literature.
I personally think that in utero testing for autism and autism-like disorders will not work. There will be too many false-positives. I personally think that women will be unwilling to abort 2, or 4, or 6 completely healthy non-ASD fetuses to avoid bringing a single ASD fetus to term. Depending on their genetic background, some couples may be unable to conceive a fetus that does not register positive for an ASD.
Thanks! I work with autistic females and wrote to BC about 3 years ago expressing my concern that his extreme male brain theory did not include sensory sensitivities and that when creating the Autism questionaire he did not have a autistic female only control group. Working practically, it becomes obvious which researchers are following observations, in contrast to those who work in rooms with no windows. Check out Olga Bogdashina.
Thoughts Regarding Autism Spectrum Neurodevelopmental Disorders
Of these rare neurological disorders, Autism is the most common. The autism spectrum reflects the broad range of symptoms in which the names of these autism disorders have been given their own name for their disorder.
Autism is a disability that is suspected to be caused possibly by a brain development disorder of unknown etiology. Others suspect the cause is some sort of neurological dysfunction- possibly with a genetic predisposition. Autism is about 3 times more common in males than females as well, and it is unclear as to why this occurs.
Usually, symptoms of the disease present themselves before the toddler reaches the age of three. Before Autism was more understood, others inaccurately labeled autistic people as childhood schizophrenia or as having a psychosis or mental retardation.
Symptoms of the autistic patient included limited or dysfunctional social and personal or intimate relationships with others, their intelligence is affected, and the autistic person typically is adverse to change. Also, the autistic person tends to be compulsive and prefers to be alone. They lack eye contact as much as physical contact with other people.
Out of over two dozen diagnostic criteria utilized for these disorders, eight must be present to be considered autistic, according to the DSM. As with all passive developmental disorders, the person expresses language, social, and behavioral difficulties.
Treatment includes what are called psychotropic medications that delay the progression of the disorder, as well as relieve some of the symptoms of one who is autistic. Behavioral therapy is common as a treatment regimen as well. Boys get Autism much more than girls.
Then there is the controversy between many who claim that thimerosal- a preservative containing mercury, which is a neurotoxin that was used in vaccines until 2001, was the catalyst for autism in children.
Over 5000 lawsuits have been filed because of this belief, and some have been successful for the plaintiff. Yet most agree the correlation between thimersal and autism is void of scientific merit. Furthermore, the cases of autism have not decreased since the preservative was discontinued in 2001.
Aside from Autism, the other four passive developmental disorders are known as autism spectrum disorders.
Asperger’s Syndrome is more common than autism, and the symptoms are milder, as there is minimal delay in language abilities, if at all. What is expressed with Asperger’s syndrome is mild autistic symptoms. In time, the patient may express atypical personality disorders, though.
While intelligence is within normal limits with the Asperger’s patient, social interactions and abilities preset difficulty for such a patient. As with Autism, medications and behavioral therapy are treatment regimens with one with this syndrome
Rett’s Syndrome or disorder presents with not only atypical behavior, but also suffers from restricted physical growth and movement. There is cognitive and social impairment as well. The disorder affects mostly girls, and the cause is due to a gene mutation.
Childhood Disintegrative disorder is rare, and is 10 times less common than autism. The disorder has a late onset with mild autistic symptoms. The disorder affects mostly boys, and regression is sudden and possible with this disorder. Skills lost with this disorder may be language, social, self-care, as well as play or motor skills. Decreased function or impairment with this disorder may include social skills and behavioral flaws. Central Nervous System pathology is a suspected cause of this disorder.
Finally, there are passive development disorders that are not otherwise specified. This may include atypical autism, for example. Yet as with the rest of types of these disorders, the symptoms vary in their frequency and intensity, as well as the range of abilities of these developmental disorders vary widely as well.
Medicinal treatment is believed to be not necessary for the management of all of those who may have autistic spectrum disorders. Depending on the patient’s health care provider, medications may be prescribed by their doctor to manage any affective disorders autistics may present in an acute or chronic nature. However, cognitive and behavioral therapy prove to be most beneficial for all the different types of Passive Development Disorders that exist for reasons yet to be defined.
www.autism-society.org
Dan Abshear
Autism as become an umbrella diagnosis. It includes - hyperlexia, aspergers, pdd, etc. so it seems like more people than ver have the diagnosis. I believe excessive testosterone may bbe a factor, especially in dually diagnosed people. i.e.: autism w/ bi-polar or autism/pdd with explosive personality disorder. Interesting article.
If one wants to measure fetal testosterone-autism links wouldn't the natural first step to do a study of digit ratio, which is a fetal testosterone marker with autism traits in a much larger sample (since the pheomena is much cheaper to study)?
(The digit ratio test has, of course, already been done, e.g. in Manning (2001), but with a sample that is quite small given the low cost of a large sample in that kind of study. Other studies along the same lines are Milne (2006) and De Bruin (2007).
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