Investigators find that ADHD drug MPH impacts the brain differently depending on age.
Liesbeth Reneman, MD, PhD
New research suggests a common ADHD medication affects the brain’s signal-carrying white matter in children, but not in adults suffering from the disorder.
Study senior author Liesbeth Reneman, MD, PhD, from the Department of Radiology and Nuclear Medicine at the Academic Medical Center, University of Amsterdam, led a team in discovering that methylphenidate (MPH), also sold as Ritalin and Concerta, affects the development of the area of the brain associated with learning, brain functions, and coordinating communication between different brain regions in children.
The investigators examined 50 male children and 49 young adult men diagnosed with ADHD that had never received MPH prior to the study. Each patient received either MPH or a placebo for 16 weeks and underwent an MRI, including diffusion tensor imaging (DTI), before and 1 week after treatment cessation to help assess white matter.
DTI helps provide fractional anisotropy (FA), which reflects crucial aspects of white matter such as nerve fiber density, size, and myelination—the process of coating nerve fibers to protect the nerve and help it efficiently carry signals.
The investigators found increased white matter in FA were dependent on age and were not observed in the adults treated with MPH.
“The results show that ADHD medications can have different effects on the development of brain structure in children versus adults,” Reneman said in a statement. “In adult men with ADHD, and both boys and adult men receiving placebo, changes in FA measures were not present, suggesting that the effects of methylphenidate on brain white matter are modulated by age.”
The investigators are examining the long-term implications of the study’s findings on ADHD behavior, which have yet to be established. A significant amount of ADHD patients is on medication for several years, making it difficult to study the long-term impacts of MPH.
The team also advocate for more stringent regulations for prescribing ADHD medications because MPH is being prescribed to an increasing number of children at younger ages.
“What our data already underscore is that the use of ADHD medications in children must be carefully considered until more is known about the long-term consequences of prescribing methylphenidate at a young age,” Reneman said. “The drug should only be prescribed to children who actually have ADHD and are significantly affected by it.”
According to the Center for Disease Control and Prevention, based on parent reporting, approximately 5.2% of American children between the ages of 2 and 17 take ADHD medication.
In an another ADHD study, lead investigator Alison Poulton, MD, MB, from the University of Sydney, told MD Magazine® in May that current MPH dosage guidelines are inadequate.
“Dosage guidelines do not acknowledge any clinical dilemma in patients who may not be adequately treated within the specified dose range,” she said. “This may mean that some patients are under-treated or that prescribing doctors may start adding in other drugs, increasing the risk of adverse effects and drug interactions.”