Sep 29 2008

A Behaviorial Marker for Autism

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Autism researchers at the Yale Child Study Center have published the results of their research looking at the behavior of 2 year old children with autism. Specifically, they used eye-tracking software to see where they were focusing their gaze when looking at someone who is talking with them.

Lead author Warren Jones, with Ami Klin and Katelin Carr, found that children with autism tend to look at the mouth of someone who is talking, while children without autism tend to look at the eyes.

From the abstract:

Participants  Fifteen 2-year-old children with autism were compared with 36 typically developing children and with 15 developmentally delayed but nonautistic children.

Main Outcome Measure  Preferential attention was measured as percentage of visual fixation time to 4 regions of interest: eyes, mouth, body, and object. Level of social disability was assessed by the Autism Diagnostic Observation Schedule.

Results  Looking at the eyes of others was significantly decreased in 2-year-old children with autism (P < .001), while looking at mouths was increased (P < .01) in comparison with both control groups. The 2 control groups were not distinguishable on the basis of fixation patterns. In addition, fixation on eyes by the children with autism correlated with their level of social disability; less fixation on eyes predicted greater social disability (r = – 0.669, P < .01).

The hallmark of autism, or autism spectrum disorder (ASD), is decreased social ability. Children with autism simply do not engage socially as much as children without autism. In the most extreme cases children with autism will be withdrawn into their own world, uninterested in anyone around them.

There are many measures that can be used for this decrease in social interaction, but (being highly social creatures) parents are usually the first to recognize autism in their children simply by their subjective or emotional experience.

What this technique provides is a good quantitative measure. This is not the first study to use eye-tracking software to study autism. In this study, for example, researchers used eye tracking software and found that children with autism look at faces less often than controls, while children with another disorder, Williams Syndrome, which is characterized by decreased IQ but an increase in social behavior, had an increase attendance to faces. Therefore looking at human faces (and now eyes) appears to be a good marker for social ability.

The researchers speculate that those with autism prefer to look at the mouth when someone is speaking because they make a causal connection between the mouth moving and the words they are hearing. However, they are not making a social connection between the words and the person who is speaking. The physical has meaning for them while the social does not. This sounds plausible and consistent with our current understanding of autism.

The researchers next plan to study children prospectively from birth to see if preference for looking at mouths over eyes can predict the later development of autism.This may provide a powerful tool for the early screening and diagnosis of autism. The potential benefit of this is that it would allow for earlier intervention of behavioral therapy meant to compensate at least somewhat for the decreased social potential in these children.

Another potential benefit of such a study would be to confirm that, at least in some children, autism is present and detectable at birth or shortly thereafter. This has obvious implications for the vaccine-autism claim – if autism can be detected prior to the vaccine schedule, that would rule out vaccines as a contributing cause. Although the autism-vaccine claim has already been thoroughly debunked, it remains a public controversy.

There is already evidence that the signs of autism are detectable in infancy, but confidence in science comes from multiple independent lines of evidence pointing in the same direction. So this research would be welcome.

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