Scientific Method / Science & Exploration

Hyperactivity helps ADHD boys with memorization

Hyperactivity could be more than a simple byproduct of inattention in those …

Many adults are quick to tell children to stop fidgeting or moving around too much when it’s time to focus on tasks like learning letters and numbers. Children with ADHD (Attention-Deficit/Hyperactivity Disorder) are particularly prone to problems when it comes to sitting still while doing things that require working memory, the memory that’s necessary for temporarily processing and manipulating information. The hyperactive behavior is often associated with inattentiveness, but psychology professor Mark Rapport and his fellow researchers report in the Journal of Abnormal Child Psychology that it may actually help children with ADHD concentrate on the task at hand.

There isn’t a general agreement among psychologists regarding the role of hyperactivity. Some argue that it’s merely an incidental byproduct of a lack of concentration, while other models of ADHD propose that it has a practical function. Research groups have tried to connect hyperactivity with tasks that require attentive working memory, but they've had little success. Rapport’s team suggests that past research attempts suffered from flawed experimental designs such as using subjective ratings from parents and teachers to approximate a child’s activity level. Thus, they sought more objective methods for measuring this.

Rapport and his colleagues had their study participants (12 individuals with ADHD and 11 controls, all boys between 8 and 12 years of age) wear actigraphs, devices that are sensitive to acceleration and used to measure intensity of movements. They placed an actigraph, which resembles a watch, on the wrist of the nondominant hand and both ankles. As the boys went through controlled and experimental tasks, the actigraphs sampled their movements 16 times every second.

The control activity involved having children use Microsoft Paint to draw whatever they liked, which required very little working memory. The experimental task required the children to play two memory games. In the game with numbers and letters, the researchers showed the boys a random series of numbers along with a capital letter for 800 milliseconds. They then asked the boys to recite the numbers in ascending order, followed by the letter. In the other game, they presented nine squares. In each trial, a series of black and red dots would appear on the squares—they showed every dot for 800 milliseconds. At the end of every trial, the boys had to remember the position of the dots in the order that they were shown.

In all of the tasks, boys with ADHD were more physically active than the control children. However, both groups showed the same pattern when it came to performing tasks that challenged working memory. Relative to their level of activity in using Microsoft Paint, both groups displayed more than a two-fold increase in hyperactivity during the memory tasks. They fidgeted more and often swiveled around in their chairs.

Rapport and his colleagues propose that their findings suggest that "activity may serve a purposeful function in all children to the extent that arousal is necessary for central executive processing and becomes excessive in some children to compensate for chronic cortical under-arousal," which is common in ADHD. Thus, it might be counterproductive to tell children to stop fidgeting when they’re doing tasks that require a lot of focus, provided that their actions aren’t destructive.

While the authors succeeded in correlating the use of working memory with increased physical motion for boys, more work is necessary before the role of hyperactivity can be defined confidently. For example, studies that look at the quality of performance in relation to increased hyperactivity would be useful, and it could also help to monitor brain activity during these experiments. Most obviously, girls should be included, as well.

J. Abnorm. Child Psychol., 2009. DOI: 10.1007/s10802-008-9287-8

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