The stimulant Ritalin, a drug used to help children with attention-deficit/hyperactivity disorder, may cause long-term changes in the brain.

The changes look similar to those seen with other stimulants such as amphetamine and cocaine, at least in rats, the team at the University of Buffalo found.

Clinicians consider Ritalin to be short acting. When the active dose has worked its way through the system, they consider it all gone. The research with gene expression in an animal model suggests that it has the potential for causing long-lasting changes in brain cell structure and function.

Ritalin, known generically as methylphendiate, probably is not addictive in the way drugs of abuse are if it is used properly. High doses of amphetamine and cocaine have been found to switch on genes known as "immediate early genes" in brain cells. One of the genes, called c-fos, has been linked with addiction when it is activated in certain parts of the brain.

The researchers gave rat pups sweetened milk containing methylphenidate in comparable doses to what a child would get and at similar times.

CFOs genes were activated in their brains in a pattern similar to that seen in cocaine and amphetamine use. These data do suggest that there are effects of Ritalin on cell function that outlast the short term.

Annual Meeting of the Society for Neuroscience in San Diego November 11, 2001