August 27, 2019

Methylphenidate — a drug used to treat ADHD — may affect specific tracts in brain white matter in boys with the disorder, according to findings from a randomized control trial conducted in the Netherlands. The results published in Radiology suggest that the effects are age dependent.

According to LiesbethReneman, MD, PhD,a professor of translational neuroradiology and a neuroradiologist at the Academic Medical Center, University of Amsterdam, and colleagues, methylphenidate (MPH) is highly effective in treating ADHD in up to 80% of patients. However, little is known about its effects on the development of human brain white matter — a neurological material important for learning and coordinating communication between different parts of the brain.

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“Previous studies all have tried to statistically control for the effects of ADHD medications,” Reneman said in a news release. “But we are the first to study medication-naive patients in this context, which, of course, is crucial if you want to know how ADHD medications affect the developing brain.”

Fifty boys aged 10 to 12 years and 48 men aged 23 to 40 years diagnosed with ADHD who had never been treated with stimulants participated in the randomized, double-blind, placebo-controlled trial, which took place between October 2011 and June 2015. The researchers randomly assigned treatment with MPH or placebo for 16 weeks and performed MRIs, which included diffusion-tensor imaging (DTI), before the trial and 1 week following treatment cessation.

Reneman and colleagues reported that a regions of interest (ROIs) analysis yielded no changes in FA. However, voxel-based analysis revealed significant time-by-medication-by-age interaction effects in several association tracts of the left hemisphere in MPH-treated boys (P < .05).

MPH also affected the lateral aspect of the truncus of the corpus callosum because of a greater increase in FA among boys treated with the medication, with a standardized effect size of 5.25. This change did not occur among boys receiving placebo or adult men, the researchers wrote.

“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.”

The researchers noted several limitations of the study. First, it included only boys to limit variation, since boys and girls develop brain white matter differently. Second, the complexity of examining three different brain regions limited the power of the study, they wrote. – by Joe Gramigna

Disclosures: Reneman reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.

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