Published November 2019 | Translational Psychiatry

Nearly one in two children diagnosed with autism spectrum disorder (ASD) also is diagnosed with attention deficit hyperactivity disorder (ADHD). Children with both diagnoses (ASD+) tend to have more severe symptoms, with higher rates of medication use and intensive treatments. What’s more, studies indicate that the ADHD symptoms often go under-recognized and less frequently treated in children with autism.

Now, a brain structure biomarker may help clinicians improve their diagnosis and treatment of children with ASD+.

In a study supported by a national award from the American Academy of Child and Adolescent Psychiatry, Cincinnati Children’s physicians used transcranial magnetic stimulation (TMS) to compare the brain signatures of 29 youths with ASD+ to 20 youths with autism but not ADHD (ASD-).

“We found that children with autism and ADHD had a very different brain signature than children with autism alone,” says lead author Ernest Pedapati, MD, MS, who holds joint appointments in the Divisions of Psychiatry and Neurology.

Children with ASD+ showed a marked reduction in intracortical facilitation (ICF) compared to ASD-. Children with decreased ICF also showed worsened inattention and executive function. Interestingly, ICF not only results from the cerebral cortex commonly associated with ADHD, but, notes Pedapati, “also deeper structures of the brain that are involved in movement, emotion, and motivation.” These findings concerning ICF could suggest several subcortical neural circuits specifically relevant to ASD+ symptoms.

The study is part of a larger dataset tracking how common ADHD treatments work in the brains of children with ASD. Cincinnati Children’s co-authors included Steve Wu, MD, Donald Gilbert, MD, MS, and Craig Erickson, MD, MS.