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Altered brain connections in youth with ADHD

Image highlighting the parts of brain regions that were found to be highly connected with the frontal cortex in youths with ADHD. Regions shown, from top row to bottom, are the caudate, putamen, nucleus accumbens, and amygdala.Norman et al, American Journal of Psychiatry

People living with attention-deficit/hyperactivity disorder, or ADHD, can struggle with focus and self-control. The condition’s symptoms may interfere with daily functioning in both children and adults. ADHD can make it hard for kids to succeed in school, and for adults to thrive in the workforce and in personal relationships.

ADHD is a brain condition that requires a professional diagnosis to help guide treatment. Drugs that increase the levels of certain chemicals in the brain help some people with ADHD. But they don’t work for everyone, and can have unacceptable side effects.

To design better treatments for ADHD, scientists need to understand more about how the brain works in people with the condition. Researchers have wondered if differences in the neural connections between the brain’s frontal cortex, which sits in the front of the brain, and regions deep within the brain, called subcortical regions, may underlie some symptoms of ADHD. The frontal cortex plays a role in attention and control of unwanted behaviors. The subcortical regions are involved in learning, movement, reward, and emotion.

Previous studies used a type of brain imaging called functional magnetic resonance imaging (fMRI) to look for such connections in children with symptoms of ADHD. fMRI can measure changes in brain activity in real time. But these studies have been small and returned conflicting results.

An NIH research team re-analyzed fMRI images collected in six previous studies. Altogether, those studies had obtained fMRI images from more than 1,696 youths with ADHD, aged 6 to 18, as well as almost 7,000 without the condition. In addition to using a large number of images, the researchers strictly defined the brain areas being measured. This allowed for more accurate comparisons between individual fMRI scans. Results were published March 13, 2024, in the American Journal of Psychiatry.

The team found that the brains of youth with ADHD had more activity between several subcortical regions and the frontal cortex than those in youth without the condition. The brains of youth with ADHD also showed greater connection between the frontal cortex and part of the brain called the amygdala. The amygdala helps process emotions and had been suspected to play a role in ADHD.

These results were seen regardless of children’s sex, age, race or ethnicity, socioeconomic status, or estimated intelligence. The differences in brain connectivity also didn’t appear to be affected by the presence or absence of other mental health problems, such as anxiety or depression. However, the differences found by the researchers were small and likely capture only part of the processes involved in ADHD.

“The findings from this study help further our understanding of the brain processes contributing to ADHD symptoms. Such understanding is a first step in thinking of new ways to help those who find the symptoms cause difficulties in day-to-day life,” says Dr. Philip Shaw, who helped lead the study. “But these brain changes are only part of the story. ADHD is a complex condition, and many other changes in brain connectivity will play a role.”