Slow to mature, quick to distract

ADHD study reveals brain differences

issue 23 | spring 2015

The researchers compared fMRI images of the brains of people with and without ADHD to map interconnectivity between networks. Connections that normally increase with age and are hypoconnected in ADHD are shown in blue; connections that normally decrease with age and are hyperconnected in ADHD are shown in red.

A new study of brain activity in 750 children and teens reveals a key difference in brain architecture between those with attention-deficit/hyperactivity disorder (ADHD) and those without.

Those with ADHD lag behind others of the same age in how quickly their brains form connections within, and between, key brain networks, the study suggests. The result: less-mature connections between a brain network that controls internally directed thought (such as daydreaming) and networks that allow a person to focus on externally directed tasks.

That lag in connection development may help explain why patients with ADHD become easily distracted or struggle to stay focused. The new findings, and the methods used to make them, may lead to a neuroimaging "biomarker" for better diagnosis and treatment tracking in ADHD. The same approach could also be used for other behavioral and psychiatric conditions.

The research, performed by a U-M team led by Chandra Sripada, M.D., Ph.D., used advanced computing techniques to analyze detailed functional MRI scans from 275 children and adolescents with ADHD, and 481 others without the condition. Using "connectomic" methods that can map interconnectivity between networks in the brain, the team could see how a number of different brain networks, each specialized for certain types of functions, were "talking" within and amongst themselves.

The findings are relevant to thinking about the longitudinal course of ADHD from childhood to adulthood, as some patients "grow out" of the disorder, while others face it throughout adulthood.

"We and others are interested in understanding the neural mechanisms of ADHD in hopes that we can contribute to better diagnosis and treatment," says Sripada. "But without the database of fMRI images, and the spirit of collaboration that allowed them to be compiled and shared, we would never have reached this point."

Their results were published in the Proceedings of the National Academy of Sciences.