A look at the brain's wiring can often reveal whether a person has trouble staying focused, and even whether he or she has attention deficit hyperactivity disorder, known as ADHD.

A team led by researchers at Yale University reports that they were able to identify many children and adolescents with ADHD by studying data on the strength of certain connections in their brains.

"There's an intrinsic signature," says Monica Rosenberg, a graduate student and lead author of the study in Nature Neuroscience. But the approach isn't ready for use as a diagnostic tool yet, she says.

The finding adds to the evidence that people with ADHD have a true brain disorder, not just a behavioral problem, says Mark Mahone, director of neuropsychology at the Kennedy Krieger Institute in Baltimore. "There are measurable ways that their brains are different," he says.

The latest finding came from an effort to learn more about brain connections associated with attention.

Initially, the Yale team used functional MRI, a form of magnetic resonance imaging, to monitor the brains of 25 typical people while they did something really boring. Their task was to watch a screen that showed black-and-white images of cities or mountains and press a button only when they saw a city.

"It gets really dull after a while," Rosenberg says, "so it's really hard to pay attention to over a long period of time."

During the test, the team measured the strength of thousands of connections throughout the participants' brains. And they were able to identify certain patterns that predicted a person's ability to stay focused.

What's more, these connection patterns were present even when the person wasn't trying to keep track of cities and mountains, or anything else, Rosenberg says. "We could actually look at that signature while they were resting and we could still predict their attention," she says.

The team wanted to know whether this signature could be used to assess younger people, especially those with ADHD. So they reviewed data on 113 children and adolescents whose brains had been scanned by scientists in China as part of an unrelated study. The children had also been assessed for ADHD.

The team used the information about brain connections to predict how well each child would do on the attention task with cities and mountains.

"And what we found was really surprising, and I think really cool," Rosenberg says. "When we predicted that a child would do really well on the task, they had a low ADHD score. And when we predicted they would do really poorly on the task, they had a high ADHD score, indicating that they had a severe attention deficit."

For many of the children, the researchers were able to predict not only whether they had ADHD, but how severe the problem was.

The test isn't perfect but does provide useful information, Rosenberg says. Eventually, she says, it might help psychologists and psychiatrists assess children with attention problems.

One potential limitation of the approach is that attention deficits aren't found only in people with ADHD, says Mahone. Individuals with anxiety, depression, learning disabilities and autism also have trouble staying focused, he says.

Regardless of the diagnosis, though, Mahone says, "knowing how the brain is different in a disorder, we can look at ways to help 'normalize' the brain."

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