An area known as the putamen, located deep in the center of the brain, helps to control movement and attention. Harvard researchers believe that the putamen is involved in Attention Deficit/Hyperactivity Disorder. The finding also suggests that Ritalin may not be effective in treating ADHD. When researchers examined hyperactive, inattentive boys with a new type of scanner, they found a reduced flow of blood into the putamen. When doctors gave the drug Ritalin to six of 11 of the boys in the study, blood flow into the putamen increased significantly. The same doses, however, decreased blood flow even further in five other boys. “This study points to the putamen as an important region of the brain involved in ADHD,” says Martin Teicher, associate professor of psychiatry at Harvard Medical School. “Diminished blood flow may be a new way to objectively diagnose ADHD, rather than relying strictly on reports of behavior. The study also shows that Ritalin may not be effective for all children diagnosed with the disorder.” Estimates of how many school-age children have the disorder range from 2 million to almost 4 million, a reflection of the uncertainty of diagnosis.