Signs of Autism Show Up on MRI at 6 Months of Age
Children who develop autism have pervasive abnormalities of brain white matter and altered neural developmental trajectories even before symptoms appear, researchers demonstrated on imaging studies.
At 6 months of age, at-risk infants who later showed typical symptoms of autism had higher fractional anisotropy on MRI, reflecting increased anxonal diameter, myelination, and fiber density in areas such as the left fornix (P=0.04) and the left inferior longitudinal fasciculus (P=0.01), according to Jason J. Wolff, PhD, of the University of North Carolina in Chapel Hill, and colleagues.
But by 24 months, at-risk children who did not develop the disorder had higher anisotropic values in the left anterior limb of the internal capsule (P=0.04) and for left anterior thalamic radiation (P=0.003), the researchers reported online in theÂ American Journal of Psychiatry.
“Autism is increasingly considered a disorder characterized in part by aberrant neural circuitry,” they wrote.
An enlarging body of literature is demonstrating that the abnormalities involve several areas of white matter, but the extent and course of these developmental anomalies — beginning as early as 6 months — have not previously been explored.
Accordingly, Wolff and colleagues enrolled 92 children considered to be at risk for autism because they had a sibling with the disorder, and performed diffusion tensor imaging beginning at 6 months of age.
The MRI scans — done while the children slept — were repeated at 12 months and 24 months, along with cognitive testing on the Mullen Scales of Early Learning.
At age 2, the children were assessed for behavioral development using the Autism Diagnostic Observation Schedule; at that time 28 infants met the criteria for autism spectrum disorder.
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