Report of Ritalin Risks Prompts a Federal Study
By GARDINER HARRIS
Published: July 1, 2005
ROCKVILLE, Md., June 30 - Federal health officials said Thursday that they were looking into a suggestion by a small Texas study that Ritalin and other stimulant drugs given to children might increase their risk of cancer later in life.
A team of experts from the Food and Drug Administration, the National Institutes of Health and the Environmental Protection Agency went to Texas on May 23 to examine the methods used by the researchers, who found damage to the chromosomes of 12 children who took Ritalin for three months.
Ritalin, which entered the market in 1955, has been used for decades to treat children for attention or hyperactivity problems.
Dr. David Jacobson-Kram of the Office of New Drugs at the food and drug agency said that the study, by researchers at the University of Texas and the M.D. Anderson Cancer Center, had flaws in its methodology but that its results could not be dismissed. Drugs that are known to cause cancer cause similar chromosomal changes, Dr. Jacobson-Kram said.
But other scientists cautioned that the study was far too small and its finding far too preliminary to cause alarm. The study did not include a comparison group of children who had not taken Ritalin. And federal officials said there was no reason for children currently taking Ritalin or other stimulants to stop taking them.
Dr. Lawrence Greenhill of Columbia University, an expert on Ritalin and other stimulant drugs used for children, questioned why the government was devoting so many resources to following up on the study's findings. Dr. Greenhill, like many other academic researchers, serves as a consultant for companies that make the drugs.
Several research teams are trying to reproduce the study on a larger scale, using better controls. And federal officials are examining millions of health records to determine if children who took Ritalin decades ago now have higher rates of cancer. The drug agency has also asked the makers of Ritalin-like stimulants to provide it with any information about their drugs' effects on chromosomes.
"I would say that if these data are reproducible, then that would be very concerning," Dr. Jacobson-Kram said.
He added that it would be at least a year before the results of those studies were known.
It is unclear, Dr. Jacobson-Kram said, how Ritalin might damage chromosomes.
"There's no obvious mechanism by which these drugs should be doing this," he said. "And there is nothing about them by which they clue us that they are DNA damaging."
About 29 million prescriptions were written last year in the United States for Ritalin and similar drugs to treat attention deficit disorder and hyperactivity, 23 million of them for children. The drugs are among the most widely prescribed medicines in the world.
Controversy has long surrounded their use, however, with critics saying that the medications are greatly overprescribed.
Dr. Jacobson-Kram made his presentation before an F.D.A. advisory committee called to examine the most recent reports of adverse events among children taking Concerta, a long-acting form of Ritalin. The committee found nothing new or unusual about the reports, which included cases of children who had become psychotic and others who had developed heart problems.
The drug agency said no committee members had conflicts of interest that would prevent them from evaluating the drug's safety in an independent manner.
F.D.A. officials told the committee that the agency planned to change Concerta's label to make the risks of such side effects clearer. Among the mental side effects reported among children taking Concerta were hallucinations, thoughts of suicide, psychotic behaviors and aggression.
"It's not that this is something new or that this is something that's happening at a higher incidence than before," Dr. Paul Andreason, a psychiatrist who is part of the agency's division of neuropharmacologic drug products, told the committee.
But, Dr. Andreason said, descriptions of these problems in the labels of Concerta, Ritalin and similar stimulants are often written in technical language. So the F.D.A. has decided that descriptions of the drugs' potential side effects must be stated more clearly, he said.
Still, agency officials and several committee members said they were not convinced that Concerta caused mental problems like hallucinations and psychosis. Rather, the children taking the drug may also suffer from other mental disorders.
"The agency believes that it is not yet possible to determine whether these events, especially the more serious ones, are causally associated with these treatments," said Dr. Dianne Murphy, director of the Office of Pediatric Therapeutics at the drug agency.
The most common side effects of Ritalin, Concerta and similar drugs are appetite suppression, headaches, abdominal pain and sleep disturbances. Children who take these drugs chronically often weigh less and are shorter in stature as a result.