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Using magnetic resonance imaging (MRI) to study brains of infant siblings of older children with autism, scientists were able to correctly identify 80 percent of babies who subsequently were diagnosed with autism at 2 years of age.
Researchers from the University of Washington (UW) were part of a North American effort led by the University of North Carolina to use MRI to measure brains of "low-risk" infants, with no family history of autism, compared with "high-risk" infants who had at least one older autistic sibling.
This is the first study to show that it is possible to use brain biomarkers to identify which infants in a high-risk pool — in this case, those having an older sibling with autism — will be diagnosed with Autism Spectrum Disorder, or ASD, at 24 months of age.
The predictive power of the team's findings may inform the development of a diagnostic tool for ASD which could be used in the first year of life, before behavioral symptoms emerge.
"We don't have such a tool yet," adds Estes. "But if we did, parents of high-risk infants wouldn't need to wait for a diagnosis of ASD at 2, 3 or even 4 years and researchers could start developing interventions to prevent these children from falling behind in social and communication skills."
People with ASD — which includes 3 million people in the United States — have characteristic social communication deficits and demonstrate a range of ritualistic, repetitive and stereotyped behaviors.
This research project included hundreds of children from across the country and was led by researchers at four clinical sites across the United States: the University of North Carolina-Chapel Hill, UW, Washington University in St. Louis and The Children's Hospital of Philadelphia. Other key collaborators are at the Montreal Neurological Institute, and the University of Alberta and New York University.
"We have wonderful, dedicated families involved in this study," said Stephen Dager, a UW professor of radiology and associate director of the Center on Human Development and Disability (CHDD), who led the study at the UW. "They have been willing to travel long distances to our research site and then stay up until late at night so we can collect brain imaging data on their sleeping children. The families also return for follow-up visits so we can measure how their child's brain grows over time. We could not have made these discoveries without their wholehearted participation."
Researchers obtained MRI scans of children while they were sleeping at 6, 12 and 24 months of age. The study also assessed behavior and intellectual ability at each visit, using criteria developed by Estes and her team. They found that babies who develop autism experience a hyper-expansion of brain surface area from 6 to 12 months, as compared to babies with an older sibling with autism but who themselves, did not show evidence of autism at 24 months of age. Increased surface area growth rate in the first year of life was linked to increased growth rate of brain volume in the second year of life. Brain overgrowth is tied to emergence of autistic social deficits in the second year.
Researchers input their data — MRI calculations of brain volume, surface area, and cortical thickness at 6 and 12 months of age, as well as sex of the infants — into a computer program, asking it to classify babies most likely to meet ASD criteria at 24 months of age. The program developed the best algorithm to accomplish this, and then researchers applied that algorithm to a separate set of study participants.
If these findings could form the basis for a "pre-symptomatic" diagnosis of ASD, health care professionals could intervene even earlier.
"By the time ASD is diagnosed at 2 to 4 years, often children have already fallen behind their peers in terms of social skills, communication and language," said Estes, who directs behavioral evaluations for the network. "Once you've missed those developmental milestones, catching up is a struggle for many and nearly impossible for some."
Research could then begin to examine interventions on children during a period before the syndrome is present and when the brain is most malleable. Such interventions may have a greater chance of improving outcomes than treatments started after diagnosis.
"Our hope is that early intervention — before age 2 — can change the clinical course of those children whose brain development has gone awry and help them acquire skills that they would otherwise struggle to achieve," adds Dager.
The research team has gathered additional behavioral and brain imaging data on these infants and children — such as changes in blood flow in the brain and the movement of water along white matter networks — to understand how brain connectivity and neural activity may differ between high-risk children who do and don't develop autism.
Early brain development in infants at high risk for autism spectrum disorder (1)
The research was funded by the National Institutes of Health, Autism Speaks and the Simons Foundation.
For more information, contact Estes at 206-543-1051 or firstname.lastname@example.org and Dager at 206-616-1558 or email@example.com.
Contributors: Heather Cody Hazlett, Hongbin Gu, Brent C. Munsell, Sun Hyung Kim, Martin Styner, Jason J. Wolff, Jed T. Elison, Meghan R. Swanson, Hongtu Zhu, Kelly N. Botteron, D. Louis Collins, John N. Constantino, Stephen R. Dager, Annette M. Estes, Alan C. Evans, Vladimir S. Fonov, Guido Gerig, Penelope Kostopoulos, Robert C. McKinstry, Juhi Pandey, Sarah Paterson, John R. Pruett, Robert T. Schultz, Dennis W. Shaw, Lonnie Zwaigenbaum, Joseph Piven & The IBIS Network
Grant numbers: HD055741, HD003110, R01 MH093510, 6020, 140209.
Adapted from a release by the UNC news office.
Cortical brain regions of 6 to 12 month olds, surface area measurements