Attention-focusing brain networks interact more weakly than usual in kids with attention deficit hyperactivity disorder, new Stanford research shows.
The research, published online today in Biological Psychiatry, is part of an ongoing effort to figure out how the brain differs from normal in people with ADHD. The disorder is both serious and common: It's characterized by impulsiveness, hyperactivity and difficulty paying attention, and it has been diagnosed in more than 6 million U.S. children.
"A lot of things may be happening in one's environment, but only some grab our attention," said Vinod Menon, PhD, a professor of psychiatry and behavioral sciences and the study's senior author. "The salience network helps us stop daydreaming or thinking about something that happened yesterday so we can focus on the task at hand. We found that this network's ability to regulate interactions with other brain systems is weaker in kids with ADHD."
The research could lead to better diagnostics for ADHD, Menon said. That's a big deal because, right now, diagnosis is based on subjective assessment of a child's behaviors, and the threshold of behavior considered sufficient for diagnosis varies quite widely. Doctors worry about the risks of diagnosing ADHD in kids who don't have it, or who actually suffer from a different psychiatric problem, and also about missing children who really should get a diagnosis.
But prior efforts to find an ADHD biomarker have been hampered by weak science. Many papers reporting brain-scan features of ADHD have not withstood attempts to replicate their findings.
The new study is different: Not only did Menon's team find that their analysis could distinguish ADHD patients from controls with brain scans, it did so in three independent data sets. The data, from an open-source database of fMRI scans called the ADHD-200 Consortium, was collected using a different MRI scanner and slightly different clinical assessments at each site.
"We could use biomarkers developed from one site -- New York -- to classify ADHD children in another site, Beijing," Menon said. The biomarkers also worked for the data from the third study site, which was Portland, Oregon. The fact that the findings held for all three sites gives an important level of real-world assurance that they're meaningful.
More research is still needed to investigate whether brain scans can distinguish children with ADHD from those with other psychiatric conditions. But Menon thinks the work is on track to making a practical difference for better ADHD diagnostics.
Previously: A visual deluge may provide clues to ADHD treatment, Scientists reveal link between dopamine receptor subtype and ADHD diagnosis and Study finds many teachers, doctors mistaking immaturity for ADHD
Photo by Thomas Hawk