Public health experts are at odds over the safety of prescribing drugs to treat attention deficit hyperactivity disorder (ADHD) in children. For example, the American Academy of Pediatrics recommends medication be used in conjunction with behavior therapy to treat children over the age of 6. The American Academy of Neurology, on the other hand, published a position paper in March 2013 that discouraged doctors from writing these prescriptions.

Now new research seems to have added to the growing evidence of the dangers of overprescribing ADHD medication. Researchers from Australia, Canada, and South Korea have concluded a study examining the use of the drugs and patient risk for an abnormal heart rhythm, also known as arrhythmia, immediately after receiving the prescription.

The number of children diagnosed with ADHD, currently the most common neurological disorder among children, has reached 6.4 million while the number of children receiving prescription medication, such as Ritalin and Concerta, for their condition has risen to 3.5 million. A central nervous stimulant known as methylphenidate found in some of these medications has been connected to a variety of unhealthy side effects, including permanent brain damage.

"Methylphenidate exposure in children and young people with diagnosis of ADHD is associated with arrhythmia and potentially with myocardial infarction in specific time periods of use," the research team said in a statement. "With the increased use of drugs for ADHD globally, the benefits of methylphenidate should be carefully weighed against the potential cardiovascular risks of these drugs in children and adolescents."

The research team used data from the South Korea National Health Insurance Database to measure the cardiac safety of methylphenidate among children and young adults with ADHD. Their analysis covered 1,224 cardiac events, including heart rhythm problems, high blood pressure, heart attacks, ischemic stroke, and heart failure, experienced by 114,647 people age 17 and younger. All participants were newly treated with methylphenidate starting between 2008 and 2011.

Although the researchers did not see any increased risk for hypertension, ischemic stroke, and heart failure, the findings showed that cases of arrhythmia were significantly more likely to occur during the first two months of methylphenidate use compared to months of nonuse. In fact, the risk was highest in the first two days of use. Children with existing congenital heart disease had a higher risk than most.

Because this was an observational study it does not determine whether there’s a cause and effect relationship, but more complex studies have produced similar results. Research published in the Journal of Child and Adolescent Psychopharmacology based on 714,000 children found that 111 of 8,300 who had been diagnosed with ADHD suffered from a heart problem such as irregular heartbeat, high blood pressure, cardiac arrest, or heart disease. Those prescribed ADHD medication were twice as likely to experience a cardiovascular complication.

According to the National Institutes on Drug Abuse, both types of stimulant medications used to treat ADHD, methylphenidate and amphetamine, work by increasing dopamine levels in the brain. When they are abused they can lead to malnutrition and a lack of sleep. Experts warn that methylphenidate can be habit-forming and should not be taken in a different way than prescribed by a doctor.

Source: Pratt N, Park B, Shin J. Cardiovascular Safety of Methylphenidate Among Children and Young People with Attention-Deficit/Hyperactivity Disorder (ADHD): Nationwide Self Controlled Case Series Study. BMJ. 2016.