Brain shrinkage in ADHD not caused by m...( A 10-year study by National Institute o...),Health

A 10-year study by National Institute of Mental Health (NIMH) scientists has found that brains of children and adolescents with Attention Deficit Hyperactivity Disorder (ADHD) are 3-4 percent smaller than those of children who don't have the disorder and that medication treatment is not the cause. Indeed, in this first major study to scan previously never-medicated patients, they found "strikingly smaller" white matter volumes in children who had not taken stimulant drugs. Still, the course of brain development in the ADHD patients paralleled that of normal subjects, suggesting that whatever caused the disorder happened earlier.

Drs. Xavier Castellanos, Judith Rapoport, NIMH Child Psychiatry Branch, and colleagues, report on their magnetic resonance imaging (MRI) study of 152 boys and girls with ADHD in the October 9, 2002 Journal of the American Medical Association.

Affecting 3-5 percent of school-age children, ADHD is characterized by over-activity, distractibility and impulsiveness. The disorder affects two to three times as many boys as girls, with as many as 20 percent of boys taking stimulant medication in some school systems. The new study strengthens the validity of the diagnosis by helping to put to rest criticism that structural brain abnormalities seen in ADHD might be drug-induced.

"There is no evidence that medication harms the brain," said Castellanos, who conducted the study at NIMH before joining New York University. "It's possible that medication may promote brain maturation."

Launched in l991, the study used MRI to scan 89 male and 63 female patients ages 5-18, with ADHD, and 139 age- and gender-matched controls, children and adolescents without ADHD. Most patients were scanned at least twice, and some up to four times over the decade.

As a group, ADHD patients showed 3-4 percent smaller brain volumes, in all regions. The more severe a patient's ADHD symptoms as rated by parents and clinicians th
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Contact: Jules Asher
NIMHpress@mail.nih.gov
301-443-4536
NIH/National Institute of Mental Health
8-Oct-2002

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