Long-term ADHD medication use does not appear to permanently alter the developing brain

Long-term use of stimulant medication for attention-deficit/hyperactivity disorder (ADHD) does not appear to cause lasting changes in brain development, according to a study published in Progress in Neuro-Psychopharmacology and Biological Psychiatry.

Medications such as methylphenidate, commonly known as Ritalin, are widely prescribed to treat ADHD. This condition is marked by persistent patterns of inattention, hyperactivity, and impulsivity. Stimulant medications work by increasing levels of brain chemicals, particularly dopamine and noradrenaline, which help regulate attention and behavior.

Although these medications are considered highly effective in the short term, scientists have long debated whether taking them during childhood while the brain is still developing might lead to lasting biological changes. Animal studies have suggested that exposure during sensitive developmental periods could alter how the brain’s dopamine system matures, raising questions about possible long-term effects.

Led by Zarah van der Pal from the University of Amsterdam, researchers in the Netherlands conducted a four-year follow-up of participants who had previously taken part in a randomized controlled trial over 16 weeks.

The original trial included boys and adult men with ADHD who were given either methylphenidate or a placebo for four months. In the earlier study, children but not adults demonstrated changes in how their brains responded to the medication even after treatment stopped.

The new study followed 56 males with ADHD: 32 adolescents aged on average 11 years old at the start of the original study, and 24 adults aged on average 30 years. Over the next four years, some participants continued taking stimulant medication in routine clinical care, while others did not.

At both the beginning of the study and four years later, participants underwent brain scans (pharmacological magnetic resonance imaging) before and after taking a single dose of methylphenidate. The researchers measured blood flow in specific brain regions involved in attention and decision-making, including the anterior cingulate cortex, medial prefrontal cortex, striatum, and thalamus. Changes in blood flow serve as an indirect marker of how active certain brain systems are.

The main finding was reassuring: the researchers found no evidence that long-term stimulant use caused lasting, age-specific changes in brain development. The short-term differences seen in children during the original trial did not remain detectable four years later.

“The previously identified short-term effects may be transient due to neuroplasticity—the brain’s ability to adapt and reorganize in response to internal and external stimuli,” the team hypothesized.

However, the researchers did identify some age-related patterns. In adults, those who had taken more stimulant medication over the four years tended to show lower resting blood flow in a deep brain region called the thalamus. In adolescents, higher medication exposure was linked to a smaller brain response in the medial prefrontal cortex when given a dose of methylphenidate.

Importantly, these patterns were already present at the beginning of the study—before any treatment began—suggesting they may reflect pre-existing brain differences rather than medication effects. The researchers also found that, in adolescents only, brain response patterns aligned with the distribution of a specific type of dopamine receptor known as the D1 receptor.

Crucially, none of the brain measures were directly linked to how severe a person’s ADHD symptoms were. This further suggests that the observed brain differences do not directly explain symptom levels.

The study does have limitations. The sample size was modest, some participants dropped out over time, and medication use during the follow-up period was not tightly controlled. In addition, only males were included, so the findings may not apply to females.

The study, “Association between long-term stimulant treatment and the functional brain response to methylphenidate in adolescents and adults with attention-deficit/hyperactivity disorder,” was authored by Zarah van der Pal, Liesbeth Reneman, Henk J.M.M. Mutsaerts, Antonia Kaiser, Marco A. Bottelier, Hilde M. Geurts, and Anouk Schrantee.