ADHD News & Research

Autism, ADHD, and OCD May Have More In Common Than Previously Thought

Similarities in the brains of kids with one of the three conditions may lead to changes in how we categorize and treat them, experts say.

July 28, 2016

Autism, ADHD, and OCD may share similar brain impairments, a new study finds — particularly in their distribution of white matter, the material responsible for connecting cells across the brain. Since as many as 15 percent of all children have one of the three conditions, researchers say, the study’s results may have wide-reaching implications that challenge old theories about this oft-overlapping set of disorders.

A team at the Centre for Addiction and Mental Health (CAMH) in Toronto, Canada conducted the research, publishing their results in the American Journal of Psychiatry on July 1, 2016. Two hundred children — with autism spectrum disorder (ASD), ADHD, OCD, or no diagnosis — underwent MRI scans focused on the brain’s white matter. The results showed that children with either ADHD, ASD, or OCD showed similar impairments in their corpus callosum — the brain’s largest and most critical white matter tract — when compared to the neurotypical children’s brains. Other smaller tracts in the brain also showed less white matter, particularly for the patients with ADHD or ASD.

Overall, the similarities were more striking in brains of those with ADHD and ASD than they were in OCD brains, which researchers hypothesized was related to the earlier age of onset of ASD and ADHD. The corpus callosum is the first white matter tract to develop in the brain, they said, giving it a more prominent role in disorders that develop earlier in a child’s life.

ADHD, ASD, and OCD share similar behaviors — like inattention, distractibility, and social challenges — that may be linked to these lower levels of white matter in the brain, researchers said. Children with more dramatic impairments in their white matter tracts demonstrated more frequent or more challenging behaviors, regardless of which of the three disorders they were diagnosed with. This may indicate that a single treatment — targeting a wide spectrum of related behaviors — may be useful in treating all three conditions, if properly developed and researched.

The study adds on to one published last month that found marked differences between ADHD and OCD brains, specifically when it comes to their levels of gray matter. The researchers wondered why two conditions with seemingly opposite levels of gray matter can co-occur in patients; this month’s study seems to indicate that the answer could be hidden in the white matter, where the conditions’ similarities seem to lie.