Ritalin: Study Shows Methylphenidate Linked to Chromosomal Changes

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Croft Woodruff

Monday, February 28, 2005 10:19 PM

 

 

 

 

Ritalin: Study Shows Methylphenidate Linked to Chromosomal Changes

 

28 Feb 2005

 

In a small but startling preliminary new study, Texas researchers have

found that after just three months, every one of a dozen children

treated for attention deficit/hyperactivity disorder (ADHD) with the

drug methylphenidate experienced a threefold increase in levels of

chromosome abnormalities-occurrences associated with increased risks

of cancer and other adverse health effects.

 

The researchers say that to their knowledge this is the first study

addressing the potential chromosome-breaking effects associated with

treatment of children with methylphenidate, the generic name for a

group of drugs that includes Ritalin, Concerta, Metadate CD and others.

 

Methylphenidate is the most widely prescribed of a class of

amphetamine-like drugs used to treat ADHD, with more than 10 million

prescriptions written for it in 1996 alone. Between 1991 and 1999,

United States sales of methylphenidate increased more than 500 percent.

 

Researchers at The University of Texas M.D. Anderson Cancer Center in

Houston and the University of Texas Medical Branch at Galveston (UTMB)

reported their detection of the chromosome abnormalities in the

journal Cancer Letters. Their peer-reviewed paper is to be published

several months hence, but the journal editors have made it available

online in the journal's " articles in press " section.

 

The authors said they undertook the study because, even though

methylphenidate has been approved for human use for more than 50

years, " there are surprisingly few studies " in either animals or human

beings " on the potential for serious side effects, " such as causing

mutations and cancer. In 1996, a report discussing several

two-year-long animal studies showed that the highest levels of

methylphenidate tested caused liver tumors in male and female mice.

However, similar studies in rats showed no such tumors.

 

The new Texas study involved researchers drawing blood from children

diagnosed with ADHD before they began taking methylphenidate in order

to get a baseline level of chromosomal abnormalities. Three months

after the children had begun taking the drug, the researchers drew the

children's blood and tested it a second time. Chromosomes are the

bodies within cells that carry the genes and genetic information. All

12 of the children whose before-and-after blood cells were studied

were treated with normal therapeutic doses of methylphenidate.

 

Most of the abnormalities found in the studied blood cells consisted

of chromosome breaks " and a higher frequency of aberrations is

reported to be associated with an increased risk of cancer down the

line, " said lead author Randa A. El-Zein, M.D., Ph.D., an assistant

professor of epidemiology at M.D. Anderson who performed the blood

studies using several techniques.

 

" It was pretty surprising that all of the children taking

methylphenidate showed an increase in chromosome abnormalities in a

relatively short period of time, " El-Zein said.

 

UTMB Professor of Environmental Toxicology Marvin Legator, the study's

principal investigator and senior author, cautioned, " This study

doesn't mean that these kids are going to get cancer, but it does mean

they are exposed to an additional risk factor, assuming that this

study holds up. " Of the 53 known human carcinogens, Legator said 48

could be detected using the chromosome analysis methods employed in

this study.

 

El-Zein stressed that much larger studies at several medical centers

are needed to confirm the results of this study and to answer other

questions not addressed by it. One of these issues is the question of

what happens when patients stop taking methylphenidate. " Do the levels

of chromosome abnormalities go back to normal? " El-Zein said. " We

don't know. "

 

Parents should respond cautiously to this preliminary study, El-Zein

said, noting that there are few alternatives to methylphenidate for

treating ADHD.

 

Asked what he would do in response to the study if his child were on

methylphenidate, co-author Matthew J. Hay, a UTMB pediatrician who

treated all the children who participated in the study, was equally

guarded. " Twelve kids with one physician in one county is too small a

sample to base a decision on, " he said. " If my child were on the

medication and were doing well, I wouldn't take him off it " unless

additional studies showed similar effects.

 

The Cancer Letters article by Randa A. El-Zein, Sherif Z.

Abdel-Rahman, Matthew J. Hay, Mirtha S. Lopez, Melissa L. Bondy, Debra

L. Morris and Marvin S. Legator can be found on the Web by clicking

the " Articles in Press " button on ScienceDirect's Cancer Letters page

( sciencedirect.com/science/journal/03043835).

 

University of Texas Medical Branch at Galveston

301 University Blvd.

Galveston, TX 77555-0144

United States

Phone 409-772-2618

Fax 409-772-6216

http://www2.utmb.edu/utmb/news/htm