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Stimulants Normalize Dysfunctional Brain Circuitry in Attention Deficit/Hyperactivity Disorder: Presented at RSNA

By Ed Susman

CHICAGO, IL -- November 29, 2004 -- Through the use a diffusion of magnetic resonance imaging technique -- diffusion tensor imaging -- researchers have pinpointed the regions of the brain that have disrupted or disturbed circuitry in children with attention deficit/hyperactivity disorder (ADHD).

"We also have seen fewer of these disrupted areas in children who have been treated for long-term periods with stimulants drugs," said Manzar Ashtari, PhD, associate professor of radiology and psychiatry, North Shore-Long Island Jewish Health System, New Hyde Park, United States.

Research on these brain circuitry disruptions and the effects of stimulants in children with these disruptions were presented here on November 29^th at the Radiological Society of North America 90^th Scientific Assembly and Annual Meeting.

Dr. Ashtari acknowledged that her findings are preliminary, but she is working with a grant from the US National Institute of Mental Health to study prospectively a group of children with ADHD to see if treatment with stimulant drugs would diminish the areas of the frontal cortex and cerebellum that show signs of disrupted circuitry.

"We found abnormality of the fiber pathways in the frontal cortex, basal ganglia, brain stem and cerebellum," she said. "These areas are involved in the processes that regular attention, impulsive behavior, motor activity and inhibition -- the key symptoms in ADHD children."

In the first part of her presentation, she described how the use of diffusion tensor imaging allows scientists to not only visualize structures of the brain "but to peel away layers of the brain and let us dig down into the brain and visualize the wires that connect circuits." Specifically, the technique is helping researchers to see if the microscopic layer of water between white matter neuron tracks is disrupted.

Dr. Ashtari and colleagues compared the brain activity of 18 children with ADHD to that of 15 children who did not have the disorder. The researchers merged the diffusion tensor images of both groups and identified areas of the brain where disruptions were common.

"Typically, ADHD is described as a chemical imbalance, but our research has shown that there may also be subtle anatomical differences in the brain that are more important in this disorder," said co-investigator Sanjiv Kumra, MD, psychiatrist, Zucker Hillside Hospital, Glen Oaks, New York, United States.

In a second study, Dr. Ashtari and colleagues enrolled 10 children with ADHD who had never been treated with ADHD treatments. She visualized their brain structures with diffusion tensor imaging and then compared the disrupted areas with similar images taken from 10 children who had been treated for ADHD with stimulants such as methylphenidate for about 2.5 years.

She said the results of the comparison show that the children using the stimulants have a more normal brain function than the children who were not treated for ADHD.

"Our results show that children who have been treated with stimulants have fewer areas of fractional anisotropy abnormalities than drug-naïve ADHD patients," Dr. Ashtari said. "These results are preliminary as they are concluded from a cross-sectional small sample."

Dr. Michael Brant-Zawadski, MD, medical director of radiology, Hoag Memorial Hospital, New Port Beach, California, United States, and moderator of a press briefing at which Dr. Ashtari outlined her studies, said, "I don't think this work is ready yet for prime time. It will require further studies to see if these results can be reproduced."

He cautioned that while diffusion tensor imaging has widespread acceptance in radiology, the use of the devices now is generally found in academic institutions for research projects.


[Presentation title: "Diffusion Tensor Imaging of Children with Attention Deficit/Hyperactivity Disorder 2." Abstract SSC15-04. "Stimulant Medications and Brain Normalization Effect in Treated ADHD Patients: A Preliminary Diffusion Tensor Imaging Study." Abstract SSC15-03]

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