Magazine article Science News

Brain Images Delve into Hyperactivity

Magazine article Science News

Brain Images Delve into Hyperactivity

Article excerpt

Two new brain-scan studies, both published in the May AMERICAN JOURNAL OF PSYCHIATRY, offer a mix of puzzling and intriguing evidence about the biology of hyperactivity.

Adults suffering from hyperactivity, dubbed attention-deficit hyperactivity disorder (ADHD) by psychiatrists, improve after treatment with stimulant medication but display no accompanying changes in brain activity, report John A. Matochik of the National Institute of Mental Health (NIMH) in Bethesda, Md., and his colleagues.

The ways in which these drugs affect the brains of people with ADHD remain elusive, the researchers add.

However, areas at the front of the brain implicated in the control of relatively automatic motor responses may malfunction in ADHD, NIMH psychiatrist Jay N. Giedd and his coworkers assert in the second study. An inability to rein in such behaviors at appropriate times, rather than inattention, may lie at the core of the disorder, they propose.

Matochik's group administered one of two stimulants to 21 men and 16 women, all diagnosed with ADHD. Each participant received two positron emission tomography (PET) scans, the first before drug treatment began and the second after 6 to 15 weeks of daily medication. PET scans measured glucose metabolism, which indicates how hard various parts of the brain are working.

At the end of the trial, two-thirds of the volunteers showed markedly less restlessness and much improved attention, the investigators say. Yet PET scans revealed no differences in glucose metabolism between those helped by medication and the remainder, whose condition stayed about the same.

"These findings may strengthen the voice of those who have taken the position that adult ADHD is an important cause of unrecognized and untreated distress," writes David Shaffer, a psychiatrist at the New York State Psychiatric Institute in New York City, in the same journal. …

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