Between 2001 and 2010, use of medications for attention deficit hyperactivity disorder increased more rapidly among adults than kids. With more than 1.5 million adults in the United States now on prescription drugs like Adderall and Ritalin, new research has shown that, in spite of safety concerns, the drugs do not appear to up the risk of serious cardiovascular issues.
In Monday's edition of the Journal of the American Medical Association, the study's researchers matched approximately 300,000 comparable nonusers to the analyzed health records of approximately 150,000 adults ages 25 to 65 who were prescribed methylphenidate (e.g. Ritalin), amphetamine (e.g. Adderall) or atomoxetine (e.g. Strattera).
The researchers found that current use of ADHD medications was not linked to greater risk of heart attack, sudden cardiac death or stroke. The new research follows controlled studies in adults and children indicating that ADHD meds can elevate blood pressure levels and lead to increases in heart rate -- studies that once prompted a U.S. Food and Drug Administration advisory committee to put a black box warning about the possibility of sudden death on psychostimulant drugs.
"We think it's important that our study did not find any evidence of increased risk of major cardiovascular events in young and middle-age adults," said Laurel A. Habel, Ph.D., a research scientist with Kaiser Permanente Northern California, Oakland, and one of the study's authors.
"But it is also important that we can't completely rule out the risk," she added.
Indeed, in spite of the comfort the new study may offer patients and health care providers, its authors acknowledge several limitations.
Because they were relying on retrospective review of records, they only knew that medications were prescribed, not whether they were actually consumed or for how long. Nor did the researchers obtain data about the quantity of medication prescribed.
"If you were given high doses of these medications versus low, would that make a difference?" Habel asked. "We didn't have the ability to look at that."
However, in an accompanying editorial, Dr. Philip Shaw of the National Human Genome Research Institute hailed the research as the "most comprehensive" and "largest" assessment of the cardiovascular safety of ADHD meds to date. It joins a November study in the New England Journal of Medicine from the same group which found no association between ADHD medications and serious cardiovascular events in children and young adults ages 2 to 24. A similar study published in May in the journal Pediatrics declared the rate of cardiovascular events among children using ADHD medication was very low.
"This adds another piece of evidence suggesting that the medications used for ADHD aren't associated with high risks of cardiovascular events," said Sean Hennessy, Ph.D., a doctor of pharmacology and director of ambulatory drug use and effects at the University of Pennsylvania and an author on that study.
Hennessy cautioned that the current papers do not say anything about the safety of these drugs in older adults -- i.e. those age 65 and older -- among whom ADHD medications are being used increasingly. But he suggested that given the ongoing research in the area, that information should be available soon.
In the meantime, he believes the news is good.
"This is all pointing in the direction of reassurance," he said.