UPTON, NY New research on Ritalin, a drug prescribed to millions of American children each year with Attention Deficit Hyperactivity Disorder (ADHD), shows for the first time how the drug acts in the human brain and why it is so effective.

The findings are reported in the January 15 issue of the Journal of Neuroscience by researchers from the U.S. Department of Energy's Brookhaven National Laboratory. The publication can be found on the Web at http://www.jneurosci.org/cgi/content/full/20014896.

Although Ritalin has been used for more than 40 years as a successful treatment for ADHD, minimal information has been gathered to date on exactly how the drug works in the brain, outside of limited animal studies. This latest study, on humans, indicates that Ritalin significantly increases levels of dopamine in the brain, thereby stimulating attention and motivational circuits that enhance ones ability to focus and complete tasks.

"For the first time, we are seeing that Ritalin given at doses commonly used to treat children with ADHD significantly increases levels of dopamine in the brain," said psychiatrist Nora Volkow, head of the research team and Associate Laboratory Director for Life Sciences at Brookhaven Lab. "This combination the ability to increase motivation and also directly activate circuits of attention is likely to be key to the beneficial effects of Ritalin."

Earlier animal and limited human studies had indicated that Ritalin interferes with the recycling of dopamine within the brain by blocking dopamine transporters. However, since these earlier studies involved injection of much higher doses of Ritalin, it was unclear whether the drug would increase extracellular dopamine at doses used therapeutically for children.

Using a technique called positron emission tomography, or PET, researchers at Brookhavens Center for Imaging and Neurosciences studied dopamine levels i
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Contact: Peter Genzer
genzer@bnl.gov
631-344-3174
DOE/Brookhaven National Laboratory
15-Jan-2001