NEW YORK, Sept. 6, 2017 /PRNewswire-USNewswire/ -- Structural abnormalities in the brain's white matter match up consistently with the severity of autistic symptoms not only in children with autism spectrum disorder (ASD), but also, to some degree, in those with attention-deficit/hyperactivity disorder (ADHD) who also have autistic traits.

This is the finding of a new study, published September 6 in JAMA Psychiatry, which highlights evidence supporting the theory that common, underlying brain mechanisms may be responsible for autistic traits seen in both diagnoses.

Led by researchers in the Department of Child and Adolescent Psychiatry at NYU School of Medicine, the new study focused on white matter—nerve bundles that transmit information between brain regions. Researchers say the link between symptom severity and white matter structural patterns was most evident in the region of the brain called the corpus callosum, which connects the left and right cerebral hemispheres and enables communication between them.
The fact that correlations could be found between ASD traits and white matter structure across diagnoses suggests shared disease mechanisms—and the existence of biomarkers that could be used potentially to guide the design of more specific, future diagnostic tests and treatments.

"It's important for both clinicians and parents to know of the possibility of co-occurring symptoms in a child with a primary diagnosis of autism or ADHD," says Adriana Di Martino, MD, senior author and associate professor in the Department of Child and Adolescent Psychiatry at NYU School of Medicine. "This work could help guide clinicians in their treatment decisions and lead to a more comprehensive, personalized intervention."

ASD and ADHD are two of the most commonly occurring pediatric neurodevelopmental disorders. The U.S. Centers for Disease Control and Prevention estimates that approximately one in 68 children suffers from some degree of ASD, while the American Psychiatric Association approximates that about five percent of US children have ADHD. Although clinical overlap between ASD and ADHD is increasingly acknowledged, the exact underlying brain mechanisms of such overlap remain unknown.

Researchers in this latest study did not find a significant correlation between ADHD and white matter structure. However, when they did isolate the results based on the severity of a child's inattention—an ADHD trait —they found inattention was significantly associated with structural changes in the corpus callosum. The authors hypothesize that abnormalities in different aspects of white matter structure might correspond to distinct patient profiles.

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