No Link Found Between ADHD Drugs and Cardiovascular Events in Adults

A study involving more than 150,000 adult users of attention deficit hyperactivity disorder (ADHD) drugs has found no evidence of a link between the medications and increased risk of heart attack, stroke, or sudden cardiac death. The study was published online last week by the Journal of the American Medical Association.

For the study, Laurel A. Habel, PhD, of Kaiser Permanente Northern California, Oakland, and colleagues analyzed computerized health records ranging from 1986 to 2007 of adults aged 25 to 64. In all, the study involved 443,198 participants, 150,359 of whom were ADHD drug users and 292,839 of whom were non-users. Each ADHD drug user was dispensed prescriptions for methylphenidate, amphetamine, or atomoxetine and was paired with two nonusers by study site, birth year, sex, and calendar year.

During the study’s follow-up period, there were 1,357 cases of heart attacks, 575 cases of stroke, and 296 instances of sudden cardiac death. However, the researchers found that ongoing or new use of ADHD drugs was not connected to a heightened risk of severe cardiovascular events when compared with nonuse or remote use. They also noted that there was “little support” found indicating an increased risk for a specific medication or duration of use. Previous cardiovascular disease or non-ADHD psychiatric conditions did not seem to have an effect in these instances.

Rate ratios “also were similar across age groups,” write the authors. “As expected, event rates were substantially higher in the Medicaid population; however, the rate ratio for current use was similar to that in other sites.”

Between 2001 and 2010, ADHD drugs were prescribed for adults at an increasingly rapid rate in comparison to prescriptions for children. "According to a 2006 U.S. Food and Drug Administration (FDA) advisory committee briefing on the safety of ADHD medications, more than 1.5 million U.S. adults were taking stimulants in 2005, and adults received approximately 32 percent of all issued prescriptions," write the study authors.

A previous study prompted by concerns that ADHD drugs were increasing the risk of heart problems in children and published in the New England Journal of Medicine in November concluded that the drugs were safe for children. Nevertheless, the American Heart Association still maintains the recommendation that children prescribed ADHD drugs undergo an EKG test to confirm good heart health before taking them.

As stated in an editorial published along with the current study, its “focus on adults is welcome.” The author of the editorial, Philip Shaw, MD, PhD, adds that “There is a paucity of research into adult ADHD, despite evidence that the disorder is common, affecting around 4% of adults.”