A Physiological Marker for Autism?
February 7, 2008 by Kristina Chew, PhD
Filed under Asperger's Syndrome, Diagnosis, Neuroscience
Scientists from Baylor University College of Medicine have identified a physiological marker that might be used to create an assessment tool for those with “higher functioning autism.” The researchers looked at the brain responses of adolescents with Asperger Syndrome when they played an interactive trust game:
In the game, one person, designated the investor, chooses an amount of money to send to a second player, the trustee. The money is tripled en route, and the trustee must then decide how much to give back to the investor. When played by normal volunteers, the game unfolds in a very characteristic fashion: generous gestures are met with generous responses, while selfish ones inspire selfishness in return………………….According to the new findings, people with Asperger’s play the game just as a nonautistic person would, but they lack the characteristic “self” signal in the brain. Normal people lack the signal only when they think that they are playing against a computer, suggesting that autistic people view interactions with other people similarly to the way that normal people think about interacting with a computer.
“This approach allows a somewhat objective look at something hopelessly subjective–sense of self,” says John Gabrieli, a neuroscientist at MIT.
Researchers suggested that the study points to the possibility that autistic persons—rather than (following the notion of “theory of mind”) not understanding what another person is doing, do not understand their own role in a social exchange. (But see one countervailing view from Matthew Belmonte of Cornell University: “”I’m skeptical about how much [the Baylor College study] tells us about which capacities are intact and engaged in autism………I’m not convinced they have a deficit at all. Maybe they have adopted a different cognitive strategy.”)
The Baylor University College of Medicine researchers hope that a diagnostic test might be developed from their findings:
They have converted the activity signal from the cingulate cortex into a simple numerical score, which correlates well with a clinical test for the severity of autism. Eventually, they hope to be able to show, for example, “that if you get a 3 rather than a 14, you are 80 percent more likely to be a high-functioning autistic,” says Montague. Such a tool could potentially also be used to test the effectiveness of new behavioral treatments, he says.
The findings were published in the February 2008 issue of Neuron and the results summarized in Technology Review (published by MIT); Chris D. Frith and Uta Frith also provide a preview of the new study in Neuron.
Jeff Stimpson
Jill Cornfield
Hello Kristina, I will take a look at the original article and post my views this week, but there is one thing that immediately came to mind. The jump from physiological marker to diagnostic testing is most often insurmountable, and unfortunately researchers, especially non-clinical researchers (by this I mean people not actively engaged in actual diagnostic and treatment research), often jump the gun in discussing a possible diagnostic tool that can be created from their findings. Our field is littered with similar findings and speculative suggestions of ‘biological tests’ for particular disorders. Cortisol and depression is probably the most well known effect that unfortunately went no where in regards to informing the creation of a diagnostic tool. The problem is an issue of specificity and sensitivity, or how well the particular findings identifies children with autism ONLY, and how often the particular findings is observed in children with autism. Statistically, the issue of sensitivity and specificity is very different than the issue of group differences (always examined at the group level), and often even when group differences are found, the marker lacks sufficient specificity and sensitivity to be clinically useful. Another problem with the excitement we sometimes see in researchers who find specific markers and suggest the creation of a diagnostic tool is COST especially as it compares to a clinical diagnosis. So we gain nothing (diagnostically) if we identify an MRI anomaly in Autism that has very high specificity and sensitivity, if such diagnostic test is as effective as a clinical diagnosis procedure of much lower cost. Although I would admit that given the cost of a full ADOS evaluation, an MRI may actually be cheaper :-). I’ll review the article and comment probably tomorrow. Cheers, Nestor.
Nestor Lopez-Duran Ph.D.
Translating Autism
Yay for signal detection, and Belmonte’s much less negative ‘read’ of the finding than Uta’s use of the ‘wrong’ terminology.
Now, I wonder how many other groups of folks might have similar selfless cognitive strategies?
If they will rerun this examination using other groups of folks for comparison we might start gaining ground on the specificity/sensitivity issues that Nestor has mentioned above.
At least there are some skeptical souls out there. How about the possibility that autistics do not. as a rule, (doesn’t do to generalise too broadly) vest crucial pieces of their identity in the perceptions and opinions of other people? On the face of it, that’s a pretty intelligent strategy.
I’ve read other reactions to the article from Aspies, raising the possibilities [of different brain activity during test] such as rerouted brain synapses or lack of need for fear.
“rerouted brain synapses or lack of need for fear”—-I suspect these would appear in my son (and also fears about things that “most” people are not so fearful about).
What especially interests me about all this is why there is such interest for a more precise? “scientific”? physiological way to diagnose autism/autism spectrum disorders. Very interesting how factors—pragmatics—play a part in determining the use of such assessments.
Hi Kristina, as you can see I’m not jumping up and down about this finding, specially as it relates to a possible improvement of diagnostic tools, but I can give your the general motivation (at least in theory) behind the apparent drive to find a more precise diagnostic tool. This is not unique to autism. It is an issue affecting all medical disorders, from psychiatry, neurology, orthopedics, etc. Mostly researchers are interested in increasing specificity, due to an implicit assumption that if we have more precise diagnoses and people are more accurately categorized (think debate about high functioning vs Asperger’s) treatment interventions can be better tailored to such more precise profiles. Now that sounds very nice, but there is another reality. We feel more comfortable in the results from “objective” precise physiological measures than clinical impressions even when there is no evidence to suggest that such physiological measures are actually more effective, reliable, or accurate. Here is an example from the medical literature: studies comparing MRI results from clinical diagnosis (Drs decision) about the presence or absence of a meniscus injury show absolutely no difference. Orthopedic surgeons can tell if you have a torn meniscus as well as an MRI, yet they continue to request MRIs and patients continue to feel better looking at their MRIs pretty pictures.
Nestor.
Nestor L. Lopez-Duran PhD
Translating Autism
I’ll say that, being (ultimately) a humanist to the core, I can see how, in some ways, diagnosis might be more of an art than a science (if that’s not too much of a cliché).
Now if they could get a specific test that would be useful earlier in the timeline of development that might be something… This test is dependent on a level of development where you can understand the game being played. By the point you can figure out what is going on and have your interest held long enough to matter, other diagnostic tests could work just as well. Who knows maybe you can figure out a way to replicate the physiological effect of the test on a two year old by giving them cookies or something. I doubt it though.
I don’t understand why a computer should be engaged in a game in a way that is different to enaging a human, except in the case you understand something about the game algorithm that might give you an advantage when playing against a computer.
Kristina, I’m guessing that’s not *really* Baylor University, which is a small, private, Baptist university in Waco, TX, but is instead Baylor College of Medicine, one of the premier medical research institutions in the country.
Yep. It’s Baylor College of Medicine in Houston.
I’ve cited them before about this genetic test.
I’ve not been comfortable with some of the media’s presentation of this study as “poor recognition of ’self’ found in high-functioning persons with autism.” Perhaps it is my philosophical self going into overdrive, but there’s an assumption, a presumption, about what “self” is. My own son would certainly struggle with this test—–but (I’m referring to what Clara Claiborne Parks said about her daughter, Jessie, in an Oliver Sacks “Nova” special of some years ago), “no one had more of a sense of a self than Jessie.”