How can you tell what someone with ADHD is thinking about? Watch how much they fidget. If they’re moving around a lot, there’s a good chance they’re thinking about something complex or cognitively demanding.
That’s why telling a student with ADHD to “sit still and focus on your work” is often a contradiction. They’re fidgeting because they’re focusing on their work. If they’re motionless, on the other hand, you might have a problem.
For people with ADHD, the current amount of activity in their bodies tends to be proportional to the current amount of activity in their brains. A study published in May found that people with ADHD showed a sharp increase in motor activity when they were engaged in a task that placed demands on working memory.
People without ADHD, on the other hand, showed a much more moderate increase in activity. Moreover, people with generalized anxiety disorder showed an increase in activity resembling that of other people without ADHD. In other words, while both ADHD and anxiety are associated with fidgeting, ADHD fidgeting may be different in that it is more closely associated with cognitively complex tasks.
There’s a reason people with ADHD fidget: because it works. Unlike children without ADHD, children with ADHD have been found to perform better on cognitive tasks when they move more. It’s unclear why this is the case, but one possibility is that moving around provides stimulation for the ADHD brain, which could bring arousal and alertness up to an optimal level.
Of course, people with ADHD don’t only fidget when engaged in cognitively demanding activities. We fidget when we’re bored. We fidget when we’re nervous. More generally, we fidget when we’re in situations that are understimulating, because fidgeting is one of the ways we correct for lack of stimulation.
In many cases, though, fidgeting is about thinking. The mental wheels are turning, and physical movement helps keep the whole machine chugging along. Once again, we don’t know why exactly physical motion is a necessary part of mental motion for people with ADHD, but one way to interpret it could be that fidgeting helps people with ADHD engage in what is otherwise a physically understimulating task – thinking.
That’s why fidgeting isn’t necessarily separate from cognitive symptoms of ADHD like inattention. How we fidget often relates to how we think, and telling someone with ADHD to stop fidgeting isn’t usually a good idea unless you also want them to stop thinking.