A brain area that may be linked to an infant's predisposition to develop autism has been identified, and it all has to do with differences in the development of the brain’s visual system. These differences may alter how some babies experience their surroundings and interact with each other, which could further affect brain development and could possibly contribute to autism spectrum disorder (ASD) traits.
This research was published in the American Journal of Psychiatry and conducted as part of the Infant Brain Imaging Study, involving nine universities in the United States and Canada. MRI scans were conducted on 384 babies at 6, 12, and 24 months of age.
The cohort was chosen as they had older siblings with ASD. These younger siblings have a higher likelihood of also developing it – previous studies found that younger siblings of children with more autistic traits like avoiding eye contact, social impairments, repetitive behaviors, and delayed language, were more likely to develop the disorder.
“Those past findings suggested that the presence of these autistic traits could tell us something about the strength of the genetic factors for autism within a family,” said Jessica Girault, who led the study. “But we couldn’t say much beyond that. The current study takes our work a step forward as we begin to parse differences in infant brain development that might be related to those genetic factors.”
In this cohort, almost 25 percent (89) of the babies were diagnosed with ASD by their second birthdays, higher than the 1 in 54 children with the disorder in the United States.
MRI scans revealed differences in the size, white matter, and functional connectivity of the babies’ visual systems. present long before any symptoms of the disorder were detected.
According to the National Autistic Society, Autism is “a lifelong developmental disability which affects how people communicate and interact with the world.” Typically, when babies are bonding with their parents, they lock eyes on their caregivers. This helps infants interpret subtle visual cues in the environment, and can determine how babies learn to relate the parent’s behavior to their own. This visual interaction is critical in cognitive, social, and emotional development.
A senior author, Joseph Piven, believes that; “the aberrant visual circuitry may be a fundamental cog in the cascade of events leading to later autism.”
“These abnormalities in the brain’s visual structures track very nicely with our earlier research into the eye movements of children with autism,” said John N. Constantino, one of the senior authors of the study, “In past research, we’ve noted that children with autism often look less at people’s faces than children without the disorder. In this study, we’ve seen that abnormal development of the visual system may be rooted in genetics because the extent of alterations in the visual systems in children as young as 6 months old was associated with the severity of autism traits in their older siblings.”
“It is particularly notable that we were able to demonstrate associations between brain findings in these infants and the behavior of their older siblings with autism,” said one of the studies author’s John R. Pruett Jr. “The convergence of brainwide fcMRI results with structural and diffusion MRI findings strengthens our confidence in these discoveries, which now can be tested in a new group of 250 infants being recruited for another study because they have affected siblings and are at very high likelihood.”
Overall, the scientists in this study agree that more research is needed, but the outcome may indicate that behavioral interventions aimed at the visual system may decrease the likelihood of the infants developing some more challenging traits associated with ASD.