Using resting-state functional magnetic resonance imaging, researchers have uncovered disrupted connections between different brain areas in children and adolescents with attention deficit hyperactivity disorder.
The research team, including Dr. Qiyong Gong of the Department of Radiology at West China Hospital of Sichuan University in China, says their findings show that resting-state functional magnetic resonance imaging (rfMRI) could be useful in providing early and accurate diagnosis of the condition.
Attention deficit hyperactivity disorder (ADHD) is a neurobehavioral developmental condition that causes concentration problems, uncontrollable behavior and overactivity.
The disorder affects children and adults, although it is much more common among children, particularly boys. According to a study from the Centers for Disease Control and Prevention, approximately 6.4 million children aged 4 to 17 years were diagnosed with ADHD in 2011-12 – a 42% increase from 2003-4.
In the past, ADHD studies using functional magnetic resonance imaging (fMRI) – which monitors brain activity as a person is focusing on a task – have identified activity in the frontostriatal circuit of the brain. This is an assortment of neural pathways in the brain’s frontal lobe that helps control a person’s behavior.
However, the investigators of this most recent study say that using fMRI, researchers have been unable to determine the “specific brain physiology” that underlies ADHD.
Therefore, the team wanted to see whether rfMRI could shed any light on such physiology. This is a technique that measures brain activity when a person is not focusing on a specific task.
For their study, published in the journal Radiology, the researchers used rfMRI on 33 boys with ADHD aged 6 to 16 years old and compared the results with that of 32 similarly aged boys without the disorder.
All participants were required to undergo executive function tests, which measure a person’s control of cognitive processes including planning, working memory, problem solving and reasoning. Individuals with ADHD tend to have impaired executive function. The results of rfMRIs were correlated with results of the executive function tests.
The team found that the boys with ADHD had altered structure and function in certain areas of the brain, such as the orbitofrontal cortex – an area involved in strategic planning. Such alterations were also found in the globus pallidus. This brain area plays a part in executive inhibitory control – the ability to control inappropriate behaviors or responses.
The researchers say these findings suggest that abnormalities in these brain regions may cause the attention problems and hyperactivity that individuals with ADHD experience.
In addition, the team discovered abnormalities in the connections between resting-state brain networks linked to executive dysfunction – abnormalities that cause cognitive, emotional and behavioral difficulties.
According to Dr. Gong, these findings show there may be more widespread brain impairments involved in ADHD than had previously been shown.
He notes that rfMRI may be a useful tool to further investigate the link between brain activity and executive function, which may lead to better characterization of ADHD patients and better understanding of underlying mechanisms of the condition.
Dr. Gong adds:
“Our results suggest the potential clinical utility of the rfMRI changes as a useful marker, which may help in diagnosis and in monitoring disease progression and, consequently, may inform timely clinical intervention in the future.”
The researchers conclude that although their findings are promising, larger studies are needed to validate them.
For future research, the team plans to investigate how resting-state brain network connectivity changes over time in ADHD patients. Furthermore, the want to look at such connectivity in ADHD subtypes.
Last year, Medical News Today reported on a study detailing how tests of brainwaves using electroencephalogram may be helpful in distinguishing ADHD subtypes.