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Imaging hyperactive brains.

The child is fidgety and impatient, interrupting conversations and ignoring the comments of others. Easily distracted, he has trouble finishing what he starts or makes careless errors along the way. The parents and family physician face a difficult question: Does the boy have attention deficit-hyperactivity disorder (ADHD), the most commonly diagnosed psychiatric condition among children?

To help resolve such questions and understand what creates the disorder, investigators are studying the brains of ADHD children. In the largest brain imaging study of ADHD children thus far, researchers from the National Institute of Mental Health (NIMH) in Bethesda, Md., have identified three regions of the brain that differ between ADHD and normal children. "The differences are small but robust," says F. Xavier Castellanos of NIMH, who led a group that used a technique called magnetic resonance imaging to compare the brains of 55 healthy boys and 57 with ADHD.

In the three identified brain regions, which have been implicated previously in the control of inhibition, planning, and decision-making, there is normally an asymmetry in volume between the left and right hemispheres of the brain, with the right side of each region being larger. But in the ADHD boys, says Castellanos, that asymmetry was absent. On the right side of the brain, all three regions were smaller than normal, and thus comparable to their counterparts in the left hemisphere.

Castellanos cautions that these observed differences cannot yet serve as a diagnostic tool. The disparity in brain regions may not even be a cause of ADHD but a result of treating it: Most of the studied ADHD boys took stimulants such as Ritalin to alleviate their symptoms. For a future study, the NIMH investigators are gathering a group of ADHD boys who have not taken any medication for their behavioral difficulties. They also plan to look at girls with ADHD, says Castellanos.
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Title Annotation:Biomedicine; brains of children with Attention Deficit Hyperactivity Disorder different from those of normal children
Author:Travis, John
Publication:Science News
Article Type:Brief Article
Date:Nov 25, 1995
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