Brain Imaging Could Detect Autism Risk in Infants as Young as 6 Months
Early intervention may help curb some of the more severe symptoms of autism. The question is, How do we identify at-risk children early enough?
Researchers say they may soon be able to identify babies at high risk of autism as early as 6 months old.
Currently, clinicians can’t diagnose autism until toddlers are about 2, when the first behavioral and language symptoms of the developmental disorder become noticeable. There is a push to identify at-risk babies earlier, though, since early intervention may be critical for halting abnormal development and preventing the most troublesome behavioral outcomes associated with autism. But while scientists are developing more sophisticated screening tests that rely on brain-imaging techniques or eye-tracking technologies that monitor an infant’s gaze to pick up early autistic signs, there is still no reliable way to diagnose the condition in younger infants.
Now, reporting in the American Journal of Psychiatry, researchers say that they may finally have a tool that will select out the highest-risk infants at just 6 months old. The innovative test, known as fractional anisotropy, measures the density of white matter, the part of brain that is rich in nerve fibers and makes up the major neural pathways that connect various regions of the brain. Specifically, the technology measures the diffusion of water through nerve-fiber tracts to gauge the density of myelin, the substance that insulates the sometimes long fibers that connect one nerve cell to another; the density of myelin serves as a rough stand-in for the density of neural connections in the brain.
The scientists, recruited 92 children from the Infant Brain Imaging Study Network, which includes four clinical sites around the country. All the infants were considered to be at higher risk of developing autism because they each had at least one older sibling affected by the disorder.
The researchers monitored the children’s brain and behavior development. At 6, 12 and 24 months, the scientists measured the density of the babies’ nerve fibers in the brain, and then tracked them to see who would end up being diagnosed with an autism spectrum disorder (ASD) by age 2 and who did not.
Children who were eventually diagnosed with ASDs were more likely to show thicker, denser nerve-fiber readings at 6 months, compared with those who didn’t develop the disorder. But by the time the infants were 2, the situation was reversed: the ASD toddlers had thinner white matter than those who did not develop autism.
“The findings suggest that early on, there is something different going on in children who develop ASDs,” says Geraldine Dawson, chief science officer of Autism Speaks who is also a professor of psychiatry at University of North Carolina Chapel Hill and a co-author of the paper. “Very early on, before the emergence of behavioral symptoms, these neural networks that connect different brain regions are not developing normally.”