Among children 8 years of age, 1 in 88 are estimated to have an autism spectrum disorder, according to the National Institute of Neurological Disorders and Stroke. Several disorders fall under this classification, including autistic disorder or classic autism, childhood disintegrative disorder, Asperger’s disorder, Rett’s disorder and pervasive developmental disorder not otherwise specified.
Some children on the autism spectrum may show signs of the disorder very early in life. For example, the Centers for Disease Control and Prevention noted that a child may not respond to her name by 12 months old.
Other children on the autism spectrum may reach normal developmental milestones up until age 18 or 24 months, then either lose skills they developed or stop gaining new ones.
Now new research has noted a risk factor for autism that can be detected as early as 7 months old with the use of eye tracking equipment.
The study included 57 infants who were considered high risk for developing autism — all of these children had an older sibling diagnosed with the disorder. These children were matched with 40 infants considered low risk for developing autism, as they did not have an older sibling with autism.
When the children were assessed at age 2, 16 of the high risk group were diagnosed with an autism spectrum disorder. These children were classified as “high-risk positive,” while the children who were in the high risk group but did not develop autism were classified as “high-risk negative.”
Researchers looked at these infants’ eye movements. While sitting on their parents’ laps, the infants watched images on a computer screen. They measured different eye movement task times, such as the time it took to begin an eye movement from a central image to the periphery of the screen.
In addition to the eye movement tasks, the study included brain imagery, specifically diffusion-weighted imaging, which shows how the neural circuits in the brain are organized.
According to a press release from the National Institutes of Health, infants who were high-risk positive took longer to shift their gaze on the overlap condition of the eye movement task than the other two groups, with the difference being 25 to 50 milliseconds on average.
The area of the brain that may be connected to this gaze-shifting difference, identified with the imaging, is the splenium of the corpus callosum. It plays an important role in connecting communication between the two brain hemispheres.
Among the low risk group, the researchers found that the larger the splenium, the quicker the gaze shift. This correlation was not noted among high-risk positive infants. The difference between the groups may be due to “differences in a brain circuit that connects the splenium to visual areas of the brain,” rather than direct differences in the splenium, according to the press release.
While the difference in gaze shifting is too quick to notice in social interactions, this finding may help physicians identify children who may go on to develop autism.
References:
National Institute of Mental Health. What is Autism Spectrum Disorder (ASD)?. Web. 25 March 2013.
http://www.nimh.nih.gov/health/publications/a-parents-guide-to-autism-spectrum-disorder/what-is-autism-spectrum-disorder-asd.shtml
Centers for Disease Control and Prevention. Facts About ASDs. Web. 25 March 2013.
http://www.cdc.gov/ncbddd/autism/facts.html
National Institute of Neurological Disorders and Stroke. Autism Fact Sheet. Web. 25 March 2013.
http://www.ninds.nih.gov/disorders/autism/detail_autism.htm
National Institutes of Health. Delay in Shifting Gaze Linked to Early Brain Development in Autism. Web. 25 March 2013.
http://www.nih.gov/news/health/mar2013/nichd-22.htm
Reviewed March 26, 2013
by Michele Blacksberg RN
Edited by Jody Smith