White matter similarities found in children with ADHD, OCD, autism

Although autism, attention deficit hyperactivity disorder (ADHD) and obsessive compulsive disorder (OCD) are all different brain impairment conditions, new research shows they have a lot in common in terms of what determines whether children will develop these conditions.

Researchers at the Centre for Addiction and Mental Health (CAMH), the Hospital for Sick Children and the Holland Bloorview Kids Rehabilitation Hospital, all in Toronto, Canada, have identified similarities in the white matter of children’s brains that suffer from autism, ADHD and OCD. The three conditions together affect about 15 percent of children, the study said.

White matter consists of bundles of nerve fibers that connect cell bodies across the brain and enable communication between different regions of the brain.

The study, published this month in the American Journal of Psychiatry, examined brain white matter in 200 children who have autism, ADHD, OCD or no diagnosis.

"We found impairments in white matter in the main tract connecting the right and left hemispheres of the brain in children with either autism, ADHD or OCD, when compared to healthy children in the control group," said Stephanie Ameis, MD, the lead author on the study and a clinician-scientist at CAMH's, in a statement. “This particular white matter tract, the corpus callosum, is the largest in the brain and among the first to develop.”

The researchers also found that children with autism and ADHD had more severe impairments affecting their brain’s white matter than those with OCD, reflecting that both autism and ADHD usually onset much earlier than OCD, and at a time when several different white matter tracts are quickly developing.

The brain’s white matter structure is associated with a spectrum of behavioral symptoms that occur across the conditions, the study found.

The study, which is part of the Province of Ontario Neurodevelopmental Disorders Network initiative, points to the discovery of treatments that could help treat all three of the conditions.