Brain scan study helps clarify effects of stimulants
Do some of the findings challenge popular concepts about how stimulants work?
On 24 December 2025 Benjamin P. Kay and 20 colleagues reported the results of an imaging study that examined the effects of stimulants and sleep on the connections among areas of the brain thought to be used in attention, arousal, and reward processes. Writing in the prestigious journal, Cell, they explained that the images showed that the brains of individuals who were taking stimulants, including many children diagnosed with ADHD, showed consistent connections among networks linked to sleep and physical arousal, but no clear changes in connections among those involved in attention. The research, which came from the lab of Nico U. F. Dosenbach of Washington University of St. Louis, is entitled, “Stimulant medications affect arousal and reward, not attention.”
Here is the visual abstract followed by the text abstract (both directly from the publication):
Prescription stimulants (e.g., methylphenidate) are thought to improve attention, but evidence from prior fMRI studies is conflicted. We utilized resting-state fMRI data from the Adolescent Brain Cognitive Development Study (n = 11,875; 8–11 years old) and validated the functional connectivity findings in a precision imaging drug trial with highly sampled (n = 5, 165–210 min each) healthy adults (methylphenidate 40 mg). Stimulant-related connectivity differences in sensorimotor regions matched fMRI patterns of daytime arousal, sleeping longer at night, and norepinephrine transporter expression. Taking stimulants reversed the effects of sleep deprivation on connectivity and school grades. Connectivity was also changed in salience and parietal memory networks, which are important for dopamine-mediated, reward-motivated learning, but not the brain’s attention systems (e.g., dorsal attention network). The combined noradrenergic and dopaminergic effects of stimulants may drive brain organization towards a more wakeful and rewarded configuration, improving task effort and persistence without effects on attention networks.
This study by Professor Kay and his colleagues is likely to generate discussion among people concerned with ADHD. For those of us who engage in those discussions, it’s important to note that the main findings are not about ADHD; rather, the study essentially found that three different parts of the brain—one of which is said to be associated with attention—show correlated rises and falls in activity. Stimulants altered those relationships in a way that supports their effects on arousal and reward, not attention, and the stimulants mitigated the effects of sleeping less.
The study did not examine “attention” in the sense of “attention to task.” It is about blood flow in areas of the brain, some of which are said to be associated with attention in a broad sense. In this sense, “attention” is a mental process that affects individuals’ capacity to focus on relevant and ignore irrelevant aspects of stimuli and it is not localized (i.e., controlled by one area of the brain), but a product of multiple areas working together; they expected that stimulants would influence parts of the brain that are called the “salience network” or “SAL” and its companion, the “parietal memory network.” As the authors wrote,
We hypothesize that stimulants reduce task-switching and thus appear outwardly to facilitate attention by elevating the perceived salience of mundane tasks (e.g., math homework) through their effect on SAL, boosting persistence and effort without affecting cognitive ability.
The research aggregated data from > 5000 children, about 6% of whom were taking stimulants. They drew these participants from the Adolescent Brain Cognitive Development Study which collects longitudinal observations of 10,000 youths from sites around the US.
Here’s a bit of good news: The report by the research team adopted open access principles, so it was published under the terms of the Creative Commons CC-BY license, so one may read it, copy it, reproduce it and more provided that one provides an appropriate citation. So, Dear Readers, help yourselves! Put on your technical glasses and thinking caps and jump right to the free report of “Stimulant medications affect arousal and reward, not attention networks.”
Reference
Kay, B. P., Wheelock, M. D., Siegel, J. S., Raut, R., Chauvin, R. J., Metoki, A., .Rajesh, A., Eck, A., Pollaro, J., Wang, A., Suljic, V., Adeyemo, B., Baden., N. J., Scheiter, K. M., Monk, J. S., Whiting, F. I., Ramirez-Perez, N., Krimmel, S. R., Shinohara, R. T., Tervo-Clemmens, B., & Dosenbach, N. U. (2025). Stimulant medications affect arousal and reward, not attention. Cell, 188(26), 7529-7545. https://doi.org/10.1016/j.cell.2025.11.039