march 20, 2013 — Children who are later diagnosed with autism have subtle but measurable differences in attention as early as 7 months of age, finds a study published today in the American Journal of Psychiatry.
Researchers found that infants who went on be diagnosed with autism are slower to shift their gaze from one object to another, compared to peers who did not receive the diagnosis. The scientists also identified specific brain circuits that seem to cause the slower response. The findings point to a problem with “sticky attention”, a phenomenon observed in older children with autism, but not well studied before in babies at risk for autism.
The study was conducted by the Infant Brain Imaging Study (IBIS) Network, which includes researchers at the Center for Autism Research at The Children’s Hospital of Philadelphia.
Results help pinpoint earliest signs of autism
“This is a very exciting study, because the impairments in shifting gaze and attention that we found in 7-month-olds may be a fundamental problem in autism,” said Robert T. Schultz, PhD, director of the Center for Autism Research at CHOP and a co-author on the study. “These results are another piece of the puzzle in pinpointing the earliest signs of autism. Understanding how autism begins and unfolds in the first years of life will pave the way for more effective interventions and better long-term outcomes for individuals with autism and their families.”
These findings suggest that 7-month-olds who go on to develop autism show subtle, yet overt, behavioral differences prior to the emergence of autism spectrum disorder (ASD). They also implicate a specific neural circuit (the splenium of the corpus callosum) which may not be functioning as it does in typically developing infants, who show more rapid orienting to visual stimuli.
The study included 97 infants: 16 high-risk infants later classified with an ASD, 40 high-risk infants not meeting ASD criteria (i.e., high-risk-negative) and 41 low-risk infants. For this study, infants participated in an eye-tracking test and a brain scan at 7 months of age and a clinical assessment at 25 months of age.
The results showed that the high-risk infants later found to have ASD were slower to orient or shift their gaze (by approximately 50 milliseconds) than both high-risk-negative and low-risk infants. In addition, visual orienting ability in low-risk infants was uniquely associated with a specific neural circuit in the brain: the splenium of the corpus callosum. This association was not found in infants later classified with ASD.
The study concluded that atypical visual orienting is an early feature of later emerging ASD and is associated with a deficit in a specific neural circuit in the brain.
Participating sites and study funding
The IBIS Network consists of research sites at The Children’s Hospital of Philadelphia, the University of North Carolina, Washington University in St. Louis, the University of Washington in Seattle, the University of Utah in Salt Lake City, and the Montreal Neurological Institute at McGill University, and is currently recruiting younger siblings of children with autism and their families for ongoing research. Funding support for the study was provided by the National Institutes of Health, Autism Speaks and the Simons Foundation Autism Research Initiative.