But several studies have supported the use of the drug. The American Medical Association says it has found little evidence that Ritalin, made by Novartis and also available generically, is over-used. Children diagnosed with the conditions exhibit a series of problems including inattentiveness, poor listening skills, failure to follow instructions and difficulty organizing tasks. Market research firm IMS Health says 13.9 million prescriptions of stimulants including Ritalin were dispensed to children during the last school year, an 81.2 percent increase from the 7.7 million recorded five years earlier. Dr. Nora Volkow and colleagues at Brookhaven National Laboratory in New York used brain scans to measure the drug's effects in the brain.
Dopamine is a neurotransmitter, or message-carrying chemical, linked with feelings of euphoria.
It is believed to beat the heart of drug addiction.