Researchers at Washington University School of Medicine in St. Louis suggest that common stimulant medications used to treat attention-deficit/hyperactivity disorder (ADHD), such as Ritalin and Adderall, may work in ways scientists didn’t previously understand. The findings challenge the long-held belief that these drugs primarily improve attention by acting directly on the brain’s attention circuits.
According to the research, published on December 24 in the journal Cell, stimulants appear to influence areas of the brain involved in arousal (wakefulness) and reward, not the neural networks traditionally linked to attention itself. This discovery could reshape how doctors think about the medications that are given to millions of children diagnosed with ADHD.
“For many years we’ve been taught that stimulants help kids focus by strengthening attention systems in the brain,” said Dr. Benjamin Kay, a pediatric neurologist and lead researcher on the study. “But our data suggests that these drugs really make children more alert and make tasks seem more rewarding, which helps them pay more attention.”
Brain Scans Reveal Surprising Effects
The scientists analyzed resting-state functional MRI scans from nearly 5,800 children aged 8 to 11 who were part of the large Adolescent Brain Cognitive Development (ABCD) Study. They compared brain connectivity patterns between children who had taken stimulant medication on the day of the scan and those who had not.
The results showed that stimulant use was linked with increased activity in brain regions tied to reward and wakefulness, but not in traditional attention centers. To confirm this, researchers also scanned five adults without ADHD before and after taking stimulants and found the same pattern — reward and arousal circuits lit up, not attention networks.
Dr. Nico Dosenbach, co-author of the study, explained that stimulants might “pre-reward” the brain, making tasks — even boring ones — feel slightly more interesting. That extra motivation, even though it isn’t improving focus directly, helps people stay with a task longer, he said.
Sleep, Stimulants and Cognitive Performance
The team also looked at how sleep interacted with medication effects. They found that children with ADHD who did not get enough sleep but took a stimulant had better school grades and test performance than those who were tired and didn’t take stimulants. However, stimulant use didn’t seem to boost performance in kids without ADHD who were well-rested.
This suggests the drugs may mask the effects of sleep deprivation — acting almost like a substitute for a good night’s rest, rather than correcting the attention issues themselves. But researchers warn this could have hidden downsides.
“Not getting enough sleep is bad for kids, and if stimulants are covering up that sleep deficit, it might lead to problems later on,” Kay said. He encouraged clinicians to consider inadequate sleep as a factor when diagnosing and treating ADHD.
Looking Ahead
The researchers say more studies are needed to understand the long-term effects of stimulant use, especially if it is helping children feel more wakeful and rewarded but not actually changing attention networks in the brain. They also note that while the drugs seem to erase the neural signature of sleep loss, this does not replace the health benefits of real sleep.
This work highlights how complex ADHD and its treatment really are, and that scientists may need to rethink how and why these medications work in the brain.
