Children who take ADHD medication have twice the risk of developing heart problems, according to a study at the National Centre for Register-based Research at Aarhus University, reports Science Nordic.

The study, which took data from 714,000 children born between 1990 and 1999, showed that the risk of developing heart problems rose from around 0.5 percent to nearly one percent among children who took ADHD medication.

While this may not seem like a high number overall, Søren Dalsgaard, who led the study, believes it is a cause for concern.

"The result is worrying. It shows that clinicians need to be aware of the risk of heart ailments when they prescribe medicine to ADHD patients," he told Science Nordic.

Bad news for Americans
While only two percent of Danish children are prescribed ADHD medication, the rate is over three times as high in the States.

Nearly nine percent of American children aged 4-17 are diagnosed with ADHD, of which 69 percent are then medicated, according to the American National Resource Center on ADHD.

That amounts to a total of 3.5 million children taking medication that doubles the risk of developing heart problems.

ADHD medications such as Ritalin and Adderall are also becoming increasingly popular among university students and young adults who use the drugs for binge-studying purposes.

But what are heart problems?
The study has been praised for its massive data sample, but the main question at this point is what exactly constitutes a heart problem.

Over half of the children with heart ailments were diagnosed with ‘unspecified heart or cardiovascular disease’, according to Science Nordic.

This could include something like an over-reaction to an elevated heart rate – a common enough symptom for ADHD drugs, which are known to cause anxiety.

That being said, 23 percent of the children with heart ailments were diagnosed with the potentially life-threatening arrhythmia, and an additional eight percent were diagnosed with high blood pressure.