Drugs used to treat ADHD in adults do not increase the risk of heart attacks, strokes or sudden death, U.S. researchers said on Monday, lifting a cloud over the popular drugs used to improve attention and focus.
The findings follow a similar study in teenagers that also found no increased risk.
People with attention deficit hyperactivity disorder, known as ADHD, are excessively restless, impulsive and easily distracted. There is no cure but symptoms can be kept in check by a combination of behavioral therapy and stimulant medications.
These drugs can increase blood pressure and heart rate. There have been some reports, including one in children, that they could increase the risk of heart attacks, strokes and sudden cardiac arrest.
In the United States, some 2.7 million children and more than 1.5 million adults have have prescriptions for ADHD drugs including Novartis' Ritalin or methylphenidate and Focalin; Johnson & Johnson's Concerta, Shire's Adderall and Vyvanse and Eli Lilly's Strattera.
"There had been concern about the cardiovascular safety of these medications," said Laurel Habel of Kaiser Permanente Northern California, whose study appears in the Journal of the American Medical Association.
Habel and colleagues used electronic medical records from more than 440,000 adults aged 25 to 64.
Of these, more than 150,000 had filled prescriptions for ADHD medications. The most commonly used drugs in the study were Ritalin (methylphenidate) and Adderall (amphetamine).
The team looked to see whether the patients taking ADHD drugs had higher rates of heart attack, sudden cardiac death and stroke than those who did not take these drugs. Among users, they also looked to see whether the risk of having heart trouble was higher when they were using the drug or after they had stopped using them.
"We didn't see any evidence that these medications increased the risk of any of these events," Habel said.
Among those in the study who had ever used ADHD medications, rates of heart problems were about the same while they were taking the drugs as they were a year after they had stopped.
Although the study cannot completely rule out an increased risk of heart problems in young and middle-aged adults, it does provide some measure of reassurance, Habel said.
"We think our results suggest these drugs do not markedly elevate the risk of cardiovascular events," she said.
The findings reinforce a similar study that found no increased risk of heart problems in children or teens.
"Since adults are more likely to have underlying cardiovascular problems than children, it is especially reassuring to learn that FDA-approved medications for ADHD do not likely pose any additional cardiovascular risk in adults with ADHD," Dr. Andrew Adesman of Steven & Alexandra Cohen Children's Medical Center of New York, who was not involved with the study, said in a statement.
"Although the investigators of this study acknowledge that the data they analyzed were not perfect, it is improbable that there will be significant differences noted in subsequent studies."