According to new research from investigators at Boston Children’s Hospital in Massachusetts, studies on longterm use of ADHD treatment drugs for children have not occurred. The findings are especially concerning given that over 2.5 million children in the U.S. receive medication for their ADHD.
Researchers who looked over previous studies, which were carried out by the drug sponsors prior to U.S. Food and Drug Administration (FDA) approval, said that the studies were either too short or had too few subjects, which would prevent them from having meaningful longterm data that successfully demonstrates safety and efficacy.
“This has large implications about the way we think about the safety and efficacy of these drugs,” said the study’s senior author, Kenneth Mandl, who is a professor of pediatrics at Harvard Medical School. “It’s also impossible to assess the kind of outcomes [from ADHD trials] that parents and physicians would be most interested in, including the impact these drugs may have on educational performance or cognitive and emotional development.”
To see what was happening with ADHD drug approval, the authors examined all ADHD medications which have been approved by the FDA. Of those 20 drugs, only three have since been discontinued. The study found that the average trial length was four weeks, with about 33% of trials lasting not even that long. The average number of participants involved in each study was 75.
“Overall, half of these drug trials included fewer than 100 participants, which is a striking number, as it is indeed quite small,” said author Florence Borgeois, MD, MPH. She added that a four week trial is incredibly short, and in no way long enough to measure the impact of ADHD medication on longterm health, and cognitive development.
The researchers note that in the last decade, drugs underwent more scrutiny by the FDA, but in many cases still fell short of desired study sizes and lengths. They also point out in their study that not a single drug approved for ADHD in the U.S. meets the current international recommendations for the testing of drugs used to treat chronic conditions that are not life threatening.
Dr. Borgeois adds that the study is not meant to be alarmist in nature; most of the drugs have been on the market for years now, and their effects are fairly well known. “But there is some debate over how effective they are in the long term, and it’s important that parents are aware of what is known about the benefits of these drugs and what is not known,” she says.