Attention-deficit hyperactivity disorder, or ADHD in short, is a long-term condition that includes a combination of different problems, e.g., having a hard time paying attention, being hyperactive or being impulsive, or simply having difficulty managing everyday tasks.
ADHD affects millions of children, which often continues into adulthood as well.
Some people consume drugs to regulate their brain functions and concentration level and maintain balance, while researchers predict that the drugs may not work the way we think they will actually affect the brain.
Brain scans show ADHD stimulants don’t directly improve attention as once thought, and instead, they make the brain more alert and motivated, sometimes mimicking the effects of a good night’s sleep.
In the United States, an estimated 3.5 million children ages 3 to 17 take medication for ADHD and that number has risen as diagnoses of the neurodevelopmental disorder have become more common.
New research that began at Washington University School of Medicine in St. Louis initiated a study that was led by Benjamin Kay, MD, PhD, an assistant professor of neurology, and Nico U. Dosenbach, MD, PhD, the David M. and Tracy S. Holtzman Professor of Neurology.
The study published on December 24, 2025, in the research journal Cell, indicates that stimulants may improve performance by making people with ADHD feel more alert and more interested in what they are doing.
Instead of directly sharpening focus, the drugs appear to increase engagement with tasks.
The researchers also observed brain activity patterns that resembled the effects of a good night's sleep, counteracting the typical brain changes associated with sleep deprivation.
To examine how stimulants affect the brain, the researchers analyzed resting state functional MRI, or fMRI, data from 5,795 children ages 8 to 11 who took part in the Adolescent Brain Cognitive Development ABCD Study.
Resting state fMRI measures brain activity when a person is not performing a specific task.
The ABCD study is a long-term, multisite project following the brain development of more than 11,000 children across the U.S., including a site at WashU Medicine.
The team compared brain connectivity in children who took prescription stimulants on the day of their scan with those who did not.
Children who had taken stimulants showed stronger activity in brain regions associated with arousal and wakefulness, as well as areas involved in predicting how rewarding an activity might be.
In contrast, the scans did not show notable increases in regions classically tied to attention.
Dosenbach and Kay said their findings highlight the need for further research into the long-term effects of stimulant use on the brain.