The drug methylphenidate, the generic form of Ritalin, may cause lasting changes in brain-cell function, according to researchers at the University of Buffalo.
The prevailing belief among physicians is that the effects of the drug, widely used to treat children with attention deficit hyperactivity disorder, are short-lived. But the scientists in the new study found that the drug affects the brain even after a course of therapy.
Changes in the brain caused by Ritalin were similar to those found with other stimulant drugs, including amphetamines and cocaine, said Joan Baizer, a professor of physiology and biophysics at the University of Buffalo and the senior author of the study.
But Ms. Baizer said that the findings did not suggest that a person who takes Ritalin at therapeutic doses is more prone to addiction, which has been a controversial assertion made by some who oppose stimulant use in the treatment of children with ADHD.
“I have given the drug to my own child for years, and nothing we found calls the drug’s safety and usefulness into question,” Ms. Baizer said in an interview last week.
“We know it activates that part of the brain; we don’t know what it means. We just know that there is now more we need to know about what Ritalin does to the brain.”
The results of the study were scheduled to be presented Nov. 11 at the annual meeting of the Society of Neuroscience, held in San Diego. The study has not been published.
No Human Test
Cocaine and amphetamines activate, in certain brain cells, genes called “immediate early genes,” which make a protein that in turn activates other genes, dubbed “c-fos” genes, Ms. Baizer said.
The University of Buffalo scientists wanted to see if methylphenidate acted in the same way as amphetamines and cocaine, which both cause c-fos activity in the striatum, a part of the brain that regulates motivation and movement.
Using rats as test subjects, the scientists gave one group of rats sweetened milk with methylphenidate, and another group milk only. Ms. Baizer said she gave rats enough methylphenidate to mimic a high therapeutic dose given to children.
After a certain amount of time, the rats were killed so the scientists could study sections of the animals’ brain tissue. Ms. Baizer said that because of the need to examine brain tissue, replicating the rat study on humans is not possible.
Examination showed that the rats that had been given methylphenidate had many more neurons with c-fos activity in their brains, particularly in the striatum, than did the rats in the control group, Ms. Baizer said.
Unanswered Questions
Other Ritalin experts said the study sounded interesting, but said the university’s work left too many questions unanswered to draw any meaningful conclusions.
“Certainly, Ritalin changes the brain, otherwise behavior itself would not change,” said Russell A. Barkley, the director of psychology and a professor of psychiatry and neurology at the University of Massachusetts Medical Center in Worcester, Mass.
“The question is whether those changes endure after medication has ceased and, if they do, if those lasting changes are deleterious or actually beneficial.”
