Nov. 1, 2011 -- Medicines to treat ADHD (attention deficit hyperactivity disorder) do not seem to substantially increase the risk of serious heart problems or stroke in children and young adults. That’s the finding of a new study that included more than a million people.
When looking at the population as a whole, "these drugs don't appear to increase the risk of sudden cardiac death, heart attack, or stroke," says study researcher William O. Cooper, MD, MPH. Cooper is a professor of pediatrics and preventive medicine at Vanderbilt University in Nashville, Tenn.
Still, parents should discuss their child's personal risks with the child's doctor when making decisions about ADHD drugs, Cooper tells WebMD.
The study results drew mixed reactions from experts.
About 5.4 million children aged 4 to 17 have been diagnosed with ADHD, according to the CDC. ADHD medicines are prescribed for more than 2.7 million children in the U.S. each year to help deal with symptoms such as distraction and hyperactivity.
In the past, the use of ADHD drugs has triggered concern after reports of heart problems. In 2007, the FDA ordered makers of ADHD drugs to alert users to possible risks for heart-related problems. In 2008, the American Heart Association concluded that it was ''reasonable" for doctors to order an electrocardiogram on a child or young adult before prescribing ADHD medicine.
"It was a source of concern and confusion among parents and providers about what the risk might be," Cooper tells WebMD. "We set out to do the new study to try to do our best at answering what I considered to be a critical question.
"We do know that ADHD drugs increase heart rate and blood pressure," Cooper says. "But we don't know what effect that has in children."
The study findings appear online in the New England Journal of Medicine.
ADHD Drugs and Heart Risk: Study Details
In all, they looked at 1,200,438 children and young adults, aged 2 to 24.
They evaluated ADHD drugs in use during the study period, from 1986 to 2002. The follow-up lasted until 2005. The drugs included:
- methylphenidate (Concerta, Metadate, Methylin, Ritalin)
- dexmethylphenidate (Focalin)
- dextroamphetamines (Dexedrine, Dextrostat, Liquadd, ProCentra)
- amphetamine salts (Adderall)
- atomoxetine (Strattera)
- pemoline (Cylert)
For each patient on an ADHD medicine, the researchers selected up to two patients not on the medicine. They matched them by age and sex. The average age of the patients was 11. The follow-up averaged more than two years.
In all, 81 patients had a serious problem, Cooper tells WebMD. Of the 81 events, seven were in current users of ADHD drugs, 25 events among former users, and 49 among nonusers.
However, overall, there was no significant increase in risk for those on the medicines compared with those who were not, he says.
However, the statistical ''power'' of the study was somewhat limited, Cooper says. For that reason, he says an increased risk of heart and stroke problems among those on the medicine could not be totally ruled out. The risk could be nearly doubled, compared to those not on the drugs, he says.
But in absolute, real-life terms that estimated increased risk would still be very low, he says.
Overall, the chance of heart and stroke problems was about 3.1 per 100,000 people taking the medicine for a year, he says.
So, even if that risk nearly doubled for those on the medicine, he says, that would translate to about 5.7 serious problems for every 100,000 people taking the medicine for a year.
The study was funded by the FDA and the Agency for Healthcare Research and Quality.
Some experts found the findings more reassuring than others. "This paper does not settle the question about the safety of ADHD drugs," says Steven Nissen, MD, chair of cardiovascular medicine at Cleveland Clinic.
The researchers only looked at the most serious problems, Nissen says. He worries about the long-term effects of the drugs. He suggests parents ask for the lowest dose possible if their children need the medications.
"It doesn't settle the question, but it certainly goes a long way to allaying parents' fears about whether or not medications are safe," says Tim MacGeorge, MSW, director of the National Resource Center on ADHD, a clearinghouse of CHADD (Children and Adults with Hyperactivity Attention Deficit Disorder). "The study does help to quantify the risk."
The new study findings provide additional reassurance that the ADHD medicines ''do not put otherwise healthy patients at increased risk for serious cardiovascular events," says Andrew Adesman, MD, chief of developmental and behavioral pediatrics at Steven and Alexandra Cohen Children's Medical Center of New York, New Hyde Park.
He reviewed the findings but was not involved in the study. He reports participating in a one-day advisory board meeting for Noven Pharmaceuticals, which makes an ADHD drug.
He says the sample size of more than 1 million lends credibility to the study.
"Although the authors acknowledge that they cannot rule out a modest increase in risk, the data are overall quite reassuring, especially considering that they did not exclude children with congenital heart disease -- a group presumed to be at increased cardiovascular risk [already] -- from the analysis," Adesman says.