This is the VOA Special English Health Report.
is attention deficit hyperactivity disorder. Children with A.D.H.D. might have
trouble paying attention. They might not seem to listen. They might forget
things. They might not be able to stay seated or play quietly.
They might talk too much. And they might act and speak
without thinking about the results of their behavior. These are among the signs
listed on the Web site of the Centers for Disease Control and Prevention in the
usually identify A.D.H.D. in children. But experts say the behaviors often last
Researchers have been looking for the cause or causes
of attention deficit hyperactivity disorder. Now, a brain-imaging study offers
more evidence that could lead to new ways to treat it.
say they observed shortages in the brain's reward system in patients with
A.D.H.D. The study found that levels of certain proteins were lower than normal.
Nora Volkow is director of the
National Institute on Drug Abuse and the lead author of the study. She says the
lack of attention and self-control that mark A.D.H.D. could be caused by problems
in the flow of dopamine.
NORA VOLKOW: "Dopamine is considered a
neurotransmitter that is crucial for our ability to perceive rewards and to be
motivated in our behavior."
people cannot sense a reward, she says, then they might have difficulty completing
Researchers compared the pathways that transmit
dopamine in fifty-three adults with A.D.H.D. to those of forty-four adults
without the disorder.
NORA VOLKOW: "There was a lower concentration of
dopamine markers in the brain of individuals with A.D.H.D., specifically in the
areas of the brain that are involved with reward and motivation."
Volkow says the dopamine levels were directly related to the severity of the
study used brain images taken at Brookhaven National Laboratory in New York
State. Gene-Jack Wang is chairman of the Brookhaven medical department. He says
the finding might also help explain why people with A.D.H.D. are more likely to
abuse drugs or overeat. He says they might be trying to increase their dopamine
levels to make up for the deficits in their reward system.
The Brookhaven Lab is part of the United
States Department of Energy. The National Institutes of Health supported the
research. The study appeared in the Journal of the American Medical
And that's the VOA Special English
Health Report, written by Caty Weaver with Carol Pearson. You can find transcripts
and MP3s of our reports and share comments at voaspecialenglish.com. I'm Mario Ritter.