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 to 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 preschool and 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.
“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, Ph.D. 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 were slower than both high-risk-negative and low-risk infants to orient or shift their gaze to objects that appeared outside their direct gaze (by approximately 50 millisceconds). Results also implicate a specific neural circuit (the splenium of the corpus callosum), which may develop differently in those at risk for ASD compared to typically developing infants, who show more rapid orienting to visual stimuli. 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.
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.