Paying attention seems like a simple concept, but the ability to focus on something actually requires a complex system of brain networks. A new study from Stanford University School of Medicine finds that the interaction between three brain networks involved in attention is abnormally weak in children with attention-deficit/hyperactivity disorder (ADHD). The findings hint at the cause of ADHD and may lead to an objective method for diagnosing the disorder.
Three networks are involved in attention:
- The salience network, which directs attention,
- The default mode network, which directs self-referential activities, like daydreaming,
- The central executive network, which directs working memory.
When the brain focuses on something, the salience network limits the output of the default mode network and increases the output from the central executive network.
The researchers used this knowledge of brain networks to conduct a study of 180 children, half with ADHD and half without ADHD. They scanned the children’s brains using functional magnetic resonance imaging (fMRI) and they evaluated the children for ADHD using traditional diagnostic methods. Afterwards, they scored the brain scans based on the synchronization between the three brain networks. They also compared their synchronicity scores to the children’s levels of ADHD severity.
Children with ADHD had weaker interactions between the three brain networks than children without ADHD. In particular, the salience network’s ability to regulate the default mode network and the central executive network is diminished in children with ADHD. The differences in connectivity between children with and without ADHD were stark enough that the researchers could distinguish which children had ADHD based on the brain imaging data alone.
The data also revealed a correlation between worse attentiveness scores and weaker brain network interactions among children with ADHD.
Currently, ADHD is diagnosed based on observed behaviors, but this study could lead to an objective diagnostic tool for ADHD. “It would be very beneficial to have a diagnostic measure that uses more objective and reliable measures, not just clinical and parental assessments of behavior. This study also demonstrates that we can develop a very robust biomarker based on functional neuroimaging to reliably differentiate children with ADHD from other kids,” stated lead study author Weidong Cai, Ph.D., instructor in psychiatry and behavioral sciences.
This research is published in the journal Biological Psychiatry.
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