Using brain-scanning technology on infants, researchers have been able to predict with 80 percent accuracy which would later meet the criteria for autism. The disorder typically is diagnosed only after age two, when behavioral symptoms begin to appear; this new research suggests that earlier diagnosis based on magnetic resonance imaging (MRI) may be possible, creating the opportunity for earlier interventions.
The study, published February 15 in Nature, focused on infants with older siblings who'd already been diagnosed with autism. Led by Heather Cody Hazlett and Joseph Piven at the University of North Carolina at Chapel Hill, the study focused on brain growth: Autistic children tend to have larger brains than those without the diagnosis.
Using MRI scans of infants at six, 12, and 24 months of age, researchers found that babies who developed autism had a much higher growth in brain surface area from six to 12 months, compared to those who were not later diagnosed with the disorder. That early hyper-expansion was linked to an increased growth rate of overall brain volume, which researchers knew was tied to the behavioral symptoms used to diagnose autism around two years of age.
Researchers fed the MRI data (including brain surface area, cortical thickness, and sex of the infants) into a computer program. That led to the development of an algorithm that could identify which infants would most likely show diagnosable symptoms by age two, which the researchers then applied to a separate set of study participants. The algorithm correctly predicted eight out of ten infants who would later meet criteria for autism. "This means we potentially can identify infants who will later develop autism, before the symptoms of autism begin to consolidate into a diagnosis," Piven told UNC Health Care.
The study could prove important, as previously there have been no biomarkers for autism before symptoms develop. Researchers can now consider opportunities for pre-symptomatic intervention, when the brain is still changing and malleable. Those could prove more successful than treatments after a child has been diagnosed; by ages 2-3, the brain has already undergone significant changes.
There are some limitations to the research: The study is small and has not yet been repeated. And it focuses on siblings of children who have already developed autism. (An estimated one out of 68 children develop autism in the United States; for those with older siblings with autism, that number may be as high as 20 out of every 100 births.) But researchers are optimistic: They're looking to repeat their results, and enrolling more families in the study.