ADHD affects connectivity across the whole brain, study confirms
Using neuroimaging data of nearly 12,000 participants, researchers have confirmed there is a need for a ‘whole brain approach’ to diagnosing, researching and treating attention-deficit hyperactivity disorder (ADHD).
Previous studies have focused instead on certain regions or networks in the brain, which scientists at the Oregon Health & Science University (OHSU) and the University of Minnesota Masonic Institute for the Developing Brain believe risks overlooking aspects of the condition that can be detected by zooming out and viewing the bigger picture.
"By evaluating the cumulative effects of regions across the entire brain, we are now looking at ADHD as a whole-brain issue, which could make it easier to predict which kids have ADHD and how severe it may be," said corresponding author Michael A. Mooney, assistant professor of medical informatics and clinical epidemiology in the OHSU School of Medicine. "Down the road, we hope this will help with early identification of kids at most risk, so they can get the help they need as soon as possible."
ADHD, which has a broad range of symptoms and severity, officially affects around 3.5% of the US population, or more than 11 million people, however, the actual figure is thought to be much higher. Presently, there is no single test that can be used to diagnose the often debilitating condition that is present in both children and adults. The best we have at the moment is a mix of medical tests to rule out other conditions, as well as anecdotal and 'symptom checklist' examinations, which form the basis of a diagnosis and inform treatment.
In this study, the researchers used neuroimaging data of nearly 12,000 children aged nine and 10 in the Adolescent Brain Development Study (ABCD), which mapped behavioral, social and brain development over a decade. With this, they constructed a polyneuro risk score (PNRS), to estimate the likelihood of an ADHD diagnosis based on connectivity across the entire brain.
Knowing the kind of connectivity issues associated with different ADHD symptoms, the researchers were able to provide a PNRS score based on the participants’ resting state functional connectivity magnetic resonance imaging (rs-fcMRI) data. The higher the score, the greater the correlation between known ADHD brain activity.
What they found was that there was a significant correlation between score and ADHD diagnosis, when the whole brain was taken into account.
"This is exciting, because much of the prior research has focused on individual regions of the brain, but our study was seeing that this isn't the case across the board," Mooney said. "In fact, there is signal from all areas of the brain that are contributing to the risk of ADHD.”
The next step, the team says, is to see if these results are consistent across different ages, with the hope of it being able to provide a robust neurological tool for diagnosis. They also hope it could help researchers zoom out to instead look at how connectivity across the brain could provide a basis for better treatment.
The current methods of diagnosis are often considered outdated, now more is known about ADHD and its many behavioral manifestations. While symptoms can involve hyperactivity, impulsivity and disruptiveness, there’s also an inattentive and distractible ‘type’, as well as a third category that’s a combination of the two extremes.
"At this stage of research, we're still evaluating the clinical utility of these findings,” said Mooney. “However, it certainly points toward not looking at behavioral conditions in a silo. "Our hope is to continue research into this area so that in the future, we can improve the method to a point that it could actually be used in health care settings, providing ADHD risk prediction and assessment."
The study was published in the Journal of Neuroscience.