Using brain imaging technology, scientists have found similarities in white matter impairments in children with autism spectrum disorder (ASD), attention-deficit hyperactivity disorder (ADHD), and obsessive compulsive disorder (OCD).
A team of Toronto-based researchers used brain imaging to examine the white matter in 200 children with ASD, ADHD, OCD, or no diagnosis. White matter is made up of bundles of nerve fibers that connect cell bodies across the brain, and enable communication between different brain regions.
“We found impairments in white matter in the main tract connecting the right and left hemispheres of the brain in children with either ASD, ADHD, or OCD, when compared to healthy children in the control group,” said Dr. Stephanie Ameis, first author on the study.
This particular white matter tract, the corpus callosum, is the largest in the brain and among the first to develop.
The research team also found children with ASD and ADHD showed more severe impairments affecting more of the brain’s white matter than those with OCD.
This finding may reflect the fact that both autism and ADHD typically have an onset at a much younger age than OCD, and at a time when a number of different white matter tracts are going through rapid development, said Ameis.
Autism, ADHD, and OCD have common symptoms and are linked by some of the same genes. Yet historically they have been studied as separate disorders. Together, these three neurodevelopmental disorders affect roughly 15 percent of children and youth.
The study is part of a major Ontario initiative, the Province of Ontario Neurodevelopmental Disorders Network (POND) that is examining various childhood brain-related disorders collectively, to better understand their similarities and differences, and develop more effective and targeted therapies.
The study has been published in the American Journal of Psychiatry.
Investigators explain that many of the behaviors that contribute to impairment in autism, ADHD, and OCD, such as attention problems or social difficulties, occur across these conditions, and differ in severity from person to person.
The researchers found that the brain’s white matter structure was associated with a spectrum of behavioral symptoms present across these diagnoses. Children with greater brain impairment also had higher impairments in functioning in daily life, regardless of their diagnosis, said Ameis.
This finding has implications for our understanding of the nature of brain-related disorders, notes senior author Dr. Evdokia Anagnostou.
The new research provides biological evidence that brain structure relates to a spectrum of behavioral symptoms that cut across different developmental conditions. As such, it highlights the shared biology among such conditions.
Investigators also believe their finding suggests that treatments targeting a spectrum of behaviors may be relevant for all three conditions.