A brain area that helps orchestrate mental activity works overtime in children with attention deficit hyperactivity disorder (ADHD), reflecting the internal struggle to hold more than one thing in mind at a time, neuroscientists reported Sunday.

The scientists used a functional magnetic imaging scanner to track signs of neural activity among 19 affected children and 23 other children who were asked to remember a simple sequence of letters. The scientists discovered that a critical mental control area, called the dorsal anterior cingulate cortex, worked much harder and, perhaps, less efficiently among children with attention problems.

This fundamental difference in brain function might be an underlying cause of the inattentiveness, impulsivity and focus problems that make it hard for ADHD children to concentrate in the classroom, the scientists said during an annual gathering of 31,000 brain researchers in Washington, D.C.
"Our findings suggest that the function as well as the structure of this brain area is different in children with ADHD," said Wayne State University biologist Tudor Puiu, who reported the team's findings Sunday at a conference held by the Society for Neuroscience.

All told, about two million US children have been diagnosed with attention problems. No one yet understands the basic neurobiology responsible for the mental ailment, which has grown more common since 2003, according to a survey by the US Health Resources and Services Administration.

The finding reported Sunday adds to growing biomedical evidence that those diagnosed with the attention disorder, arguably the most common childhood behavioral issue, have unusual patterns of brain function that can persist well into adulthood.

Overall, the brain of an ADHD child matures normally, but it may take up to three years longer to fully develop, especially in areas at the front of the brain's cortex, an outer layer of tissue important in controlling attention, reasoning and planning.

Researchers have also reported a range of specific anatomical differences among ADHD children that may be linked to behavioral problems. Earlier this month, researchers at New York University's Langone School of Medicine reported that ADHD children appeared to have a significantly thinner cortex and less gray matter than other children in some areas involved in regulating attention and emotion.

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