Children with high-functioning autism spectrum disorder (ASD) appeared to have outgrown their inability to integrate the auditory and visual cues associated with speech by the time they entered adolescence, raising the possibility of successful interventions, according to a study now available online ahead of print in Cerebral Cortex (doi: 10.1093/cercor/bht213) http://cercor.oxfordjournals.org/content/early/2013/08/27/cercor.bht213.abstract.
In the study, 226 children age five to 17 were tested for how well they could integrate seen and heard speech in varying levels of background noise. Of the 226 participants, 84 were high-functioning children with ASD, and 142 were age-matched, typically developing children.
The participants were tested under three conditions. In the auditory-alone task, researchers played audio recordings of simple words. In the visual-alone test, a video of someone enunciating the words was played without audio. In the audiovisual condition, the audio and video recordings were played together.
On the auditory-alone test, children with ASD did not perform as well as typically developing children across all age groups, with a small but significant average difference of 4.23 percent.
On the video-alone test (speechreading), children with ASD again performed worse than typically developing children across all age groups and noise levels. Of 84 participants from the ASD group, 42 (50%) were entirely unable to identify words in this condition, compared with 28 of 142 participants in the typically developing group (19.7%).
For the audiovisual test, 7- to 12-year-old children with ASD performed worse than typically developing children of the same age; however, there was no difference in performance between the older children with ASD and their typically developing counterparts.
The results are promising because they suggest that the neurophysiological circuits for speech in these children aren't fundamentally broken, and there may be something to be done to help them start socializing earlier, said lead author John Foxe, PhD, professor in the Department of Pediatrics and the Dominick P. Purpura Department of Neuroscience, as well as director of research of the Children's Evaluation and Rehabilitation Center at Albert Einstein College of Medicine of Yeshiva University.
“The findings have several implications because we know that multisensory integration is hugely important for any type of communication,” he said. “For instance, autistic children have severe communication deficits, so it's important to understand that in social environments with competing voices, they don't hear like others do or have access to the same information.
“It can be very hard for anyone to concentrate in a noisy environment, so this gives us some insight in terms of ways to control the environment to best communicate with them.”
Mark Wallace, PhD, director of the Vanderbilt Brain Institute, said the study adds a lot to the field of sensory integration, and agreed that it has the potential to influence the treatment of autistic children in the future.
“The study is very strong because it has a large age range, and it shows a true developmental change,” Dr. Wallace said.
“Its big limitation, however, is that it's a cross-sectional study rather than a longitudinal study. If the researchers were to carry out a longitudinal study successfully with the same children, then they would be hitting it out of the park, so to speak.
“Another open-ended question I'm left asking myself is whether or not children with low-functioning ASD show this same progress as they age.”
Dr. Foxe acknowledged these limitations, adding that his team is working on constructing a study that would follow the same kids from their early years through adolescence. He also wants to integrate low-functioning children with ASD into future investigations, even though these children are harder to study.
Although there is currently no definitive explanation for the results, Dr. Foxe said that two possible reasons could be a physiological change in the child's brain or years of conditioning and training.
“I've noticed that young boys who are socially isolated don't worry about it, but that's something that seems to change when they become teenagers. Over time they become more aware of their social isolation, are pushed to be more social, and learn that they need to get out there and interact with the world.
“This is just an observation, but we also have the feeling that there could be more effective therapies to help ASD children better integrate audio and visual speech signals, and we'll work toward achieving it.”
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