UNC, Caltech research finds further evidence for genetic contribution to autism

July 17, 2008 — Some parents of children with autism evaluate facial expressions differently than the rest of us – and in a way that is strikingly similar to autistic patients themselves, according to new research by psychiatrist Dr. Joe Piven of the University of North Carolina at Chapel Hill and neuroscientist Ralph Adolphs, Ph.D., of the California Institute of Technology.

Piven, Adolphs and colleague Michael Spezio, Ph.D., formerly of Caltech but now at Scripps College in Claremont, Calif., collaborated to study 42 parents of children with autism, a complex developmental disability that affects an individual’s ability to interact socially and communicate with others. Based on psychological testing, 15 of the parents were classified as being socially aloof.

“This manifests as a tendency not to prefer interactions with others, not to enjoy ‘small talk’ for the sake of the social experience and to have few close friendships involving sharing and mutual support,” said Piven, senior author of the study, Sarah Graham Kenan professor of psychiatry in the UNC School of Medicine and director of the newly established Carolina Institute for Developmental Disabilities. “This characteristic is really a variation of normal and not associated with any functional impairment.”

The parents participated in an experiment that measured how they make use of the face to judge emotions. The subjects were shown images depicting facial expressions of emotion that were digitally filtered so that only certain regions of the face were discernible – the left eye, for example, or the mouth. The subjects were then asked to decide as quickly as possible if the emotion depicted was “happy” or “fear.” The part of the face shown and the size of the revealed area randomly varied from trial to trial.

An analysis of the subjects’ correct responses revealed that “aloof” parents relied much more heavily on the mouth to recognize emotion than they did on the eyes, as compared to non-aloof parents and, to a greater extent, to a group of parents of children without autism. Prior studies by Adolphs and his colleagues have shown that humans normally evaluate emotions by looking at the eyes – but studies by Adolphs and Piven have shown that individuals with autism do not.

“We found that some parents who have a child with autism process face information in a subtly but clearly different way from other parents,” Adolphs said. “This is evidence for the hypothesis that the parents with the autistic child have brains that function somewhat differently as well.”

He and other researchers are currently investigating that idea through brain imaging studies. One area of interest is the amygdala, a region located on either side of the brain in the medial temporal lobe that is known to process information about facial emotions and may have abnormal volume in both autistic individuals and their nonautistic siblings.

The finding indicates that certain aspects of autism do run in families. Although such a genetic link was noted in the 1940s in the earliest descriptions of autism, “our study adds considerable specific detail to the story,” Adolphs said.

“Our data strongly suggest that genetic factors make a substantial contribution to autism, but that does not mean that all of the cause of autism is genetic. Together with many other studies, our study argues that genetic factors play a very important role in autism, while leaving open a role for other, environmental factors,” he said.

UNC and Caltech are currently working together to follow up on the finding by looking at the neural circuitry of face processing in parents of autistic individuals, using functional MRI in a National Institutes of Health-funded study.

“We hope that this research contributes towards a cure for autism, even if only indirectly,” Adolphs said. “Once we understand better how people with autism – and their relatives – process social information like information about the faces of other people they look at, we will be in a better position to teach them strategies for social interaction and will be able to explain to them how they differ from neurotypical people.”

Piven said that this approach may disaggregate the phenotype in autism and provide new targets for genetic studies. “In other words, it may lead us to finding genes that are responsible for the face-processing component in autism,” he said.

The researchers noted that an important part of the paper is that it is not claiming all people with autism – or their parents – are ‘impaired’. Instead, they said the study shows that parents who have children with autism – like the autistic subjects themselves – are different and do things differently.

The paper, “Selective face processing abnormalities in parents of autistic children,” is published in the journal Current Biology, and is available at http://www.current-biology.com.

The research was funded by grants from the National Institutes of Health and the Simons Foundation.

UNC School of Medicine contact: Tom Hughes, (919) 966-6047, tahughes@unch.unc.edu
News Services contact: Patric Lane, (919) 962-8596, patric_lane@unc.edu

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