Children's pupils may reveal shifting attention in ADHD, especially when off medication
The eyes are more than lenses to the outside world; they can also be windows that offer a glimpse into what's happening inside our bodies. What if the eyes could help us understand how attention shifts from one moment to the next? Scientists are now testing whether tiny changes in pupil size can serve as a physiological marker of these fluctuations in children with attention-deficit/hyperactivity…
Scientists are investigating whether changes in children's pupils can serve as a window into their fluctuating attention, particularly in those with ADHD. Pupil size naturally expands and contracts in response to brain systems that regulate alertness, arousal, and attention. In a study published in Scientific Reports, researchers examined whether these pupil movements could reveal insights into children's ADHD symptoms and how medication affects them.
They measured eye movements of children with ADHD and those without while they performed a visual memory task. Children with ADHD not on medication exhibited more fluctuation in pupil size between trials than their peers without ADHD, even when accounting for task difficulty, age, and IQ. Once medicated, these children's pupils responded more strongly during key moments in the task, but their trial-to-trial variability decreased compared to when they were off medication.
This suggests that medication might stabilize their attention. Existing tests for ADHD often average performance, obscuring the rapid, second-by-second attention shifts that are characteristic of the condition. However, eye movements like pupil dilation respond quickly to changes in mental focus, making them potentially useful indicators.
The researchers analyzed data from 50 Chilean children ages 10-12, split evenly between those with and without ADHD. They found that unmedicated ADHD children showed about 23% more pupil variability from one question to the next than controls. Within a single test trial, unmedicated ADHD children's pupil variability was lower (0.699) than the control group (0.772).
Treatment with methylphenidate significantly reduced this variability and increased pupil dilation during decision-making moments, making their patterns more similar to those without ADHD. While the findings are promising, researchers caution that pupil variability is a complex measure influenced by multiple brain processes, not just attention.
Therefore, it should not be used alone to diagnose ADHD but rather as part of a broader assessment of cognitive and physiological functions.
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