Stimulant medication improves working memory of children with ADHD, study finds

A study examining how working memory in children with ADHD varies with the use of stimulant medication found that these medications improve working memory. Both phonological and visuospatial working memory were better when children took medication and were more physically active during memory tasks. The effects of the medications on visuospatial memory were strongest in children who were most physically active during the tasks. The paper was published in Research on Child and Adolescent Psychopathology.

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition that affects attention, impulse control, and activity levels. It is commonly diagnosed in childhood (most often at the start of school) but can persist into adulthood. Symptoms include difficulty focusing, excessive movement, impulsive decision-making, and trouble organizing tasks.

Treatment for ADHD includes psychotherapy, lifestyle adjustments, and medication. Stimulant medications are the most common treatment for ADHD. These medications can help improve focus and impulse control while reducing hyperactivity. They work by increasing the levels of the neurotransmitters dopamine and norepinephrine, thereby enhancing attention and self-regulation. Common stimulants include methylphenidate (e.g., Ritalin, Concerta) and amphetamines (e.g., Adderall, Vyvanse).

Study author Emily Wiegers and her colleagues sought to examine the relationship between stimulant medication usage, body movements, and working memory performance in children with ADHD. They were particularly interested in the interaction between stimulant medication and children’s physical activity (i.e., how much they move) and its potential effects on working memory performance.

The researchers conducted a study in which they examined the working memory and physical activity levels of children with ADHD both when they were on stimulant medications and when they were not. They analyzed a publicly available dataset from the Summer Treatment Program at Florida International University—an 8-week behavioral intervention delivered in a summer camp setting for children between 6 and 12 years of age with ADHD. Data came from 43 children who participated in the camp, with an average age of 10 years, 81% of whom were boys.

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During the first two weeks of the summer camp, the researchers determined the optimal medication dose for each participating child. Next, the children were randomly assigned to either receive the medication for the following three weeks or a placebo (a similarly looking capsule with no active ingredients). After three weeks on this regimen, the groups switched for the next three weeks—the group that had been taking the placebo started taking the stimulant medication, and vice versa.

During these six weeks, the children completed an extensive battery of neurocognitive tasks on four occasions. These tasks were used to assess two types of working memory: phonological memory and visuospatial memory. Phonological memory is the ability to temporarily store and manipulate verbal information, while visuospatial memory involves holding and processing visual and spatial details. While completing the cognitive tasks, participants wore actigraphy devices in the form of watches on their wrists and ankles to track their physical movements.

Results showed that participants performed significantly better on phonological working memory tasks when they were on stimulant medication than when they were not. Additionally, participants who were more physically active during the tasks tended to perform better on these tasks.

Study participants also performed better on visuospatial working memory tasks when they were using stimulant medication compared to when they were not. More active children also tended to perform better on these tasks. Analyses revealed that the effects of the medications on visuospatial working memory performance were greater in children who were the most physically active.

“Consistent with previous research, this study found that when children are medicated, they generally perform better on PH and VS WM [phonological and visuospatial working memory] tasks. Additionally, there was a relationship between scores on PH and VS WM tasks and the level of naturally occurring movement during the task as measured by actigraphy watches. Further, this study found that there was an optimal level of movement for each individual that is helpful for WM [working memory] tasks as seen by decreased score when there is little movement or too much movement,” the study authors concluded.

The study sheds light on the effects of stimulant medication on the working memory of children with ADHD. However, it should be noted that the study only examined the two aforementioned types of working memory and did not report the effects of medication on central executive working memory—the component that controls attention, coordinates cognitive processes, and manages the flow of information between different types of memory in the brain.

The paper, “The Impact of Stimulant Medication on the Relation Between Working Memory and Activity Level in ADHD,” was authored by Emily Wiegers, Annie Garner, Morgan Jusko, Jessica N. Smith, Mileini Campez, Andrew Greiner, Elizabeth Gnagy, William E. Pelham, and Joseph Raiker Jr.