THIS ARTICLE IS MORE THAN FIVE YEARS OLD
This article is more than five years old. Autism research - and science in general - is constantly evolving, so older articles may contain information or theories that have been reevaluated since their original publication date.
Autism and attention deficit hyperactivity disorder (ADHD) have much in common: Children with either disorder are often inattentive or hyperactive, and many are diagnosed with both disorders. The two disorders also share at least some genetic risk factors.
A new study published 13 August in Human Brain Mapping suggests that in the brain, however, autism and ADHD may result from distinct, even opposite, patterns of activity. The study looks in particular at the ‘rich club network,’ a dense hub of neural connections that integrates information from different brain regions.
To accomplish hugely complex yet mundane tasks, such as driving, people need to deftly use their vision, hearing, motor skills and cognitive ability all at the same time. The rich club may be what makes this possible, by providing a hub for information exchange.
The researchers scanned the brains of 20 children with ADHD, 16 with autism and 20 controls. They mapped the long paths of neurons across the brain and looked at which neurons work in sync while a brain is at rest. They combined this structural and functional data to pinpoint the most highly connected regions, revealing the rich club network.
Children with autism may have a disorganized rich club, with too many weak connections, the new study suggests. By contrast, children with ADHD have fewer connections in this same region than controls do.
The researchers found similar results using imaging data from 85 individuals with autism and 101 controls stored in the Autism Brain Imaging Data Exchange.
The findings might explain the apparent inconsistency among studies looking at connectivity in autism. One popular theory holds that autism is the result of too many local connections and not enough long-range ones. But some studies have found weaker local connections in people with autism compared with controls.
The new study shows an excess of local connections in autism brains, but only within the rich club. It also shows that more connections does not necessarily translate to stronger functional connectivity.