Indian Researchers Discover Pupil Clues to Brain Attention Mechanisms in ADHD - Video

Tiny changes in pupil size may offer clues about how attention works in children with ADHD, according to an Indian study.

Researchers from the Indraprastha Institute of Information Technology Delhi analysed eye-tracking data from 50 children aged 10 to 12, including 28 with combined-type ADHD and 22 without a neurodevelopmental diagnosis. The findings were published in Scientific Reports.

Children completed a working-memory task in which they watched dots appear on a grid and remembered their positions while ignoring distractions. An eye tracker measured pupil diameter 1,000 times per second.

Researchers found that unmedicated children with ADHD showed about 23% greater trial-to-trial variation in pupil responses than children in the control group, after accounting for age, IQ and task difficulty. Among unmedicated children with ADHD, greater pupil variability was also linked to lower accuracy on the memory task.

However, the pattern was not straightforward. Within individual trials, pupil variability was actually lower in the ADHD group. This suggests that different measures of pupil activity may reflect different aspects of attention and brain activity.

Researchers also studied 17 children with ADHD who completed the task while taking methylphenidate and after stopping it for 24 hours. During medication use, pupils showed stronger responses and less variation between trials, making the pattern more similar to the control group. However, methylphenidate can directly affect systems that influence pupil size, so the findings cannot prove that medication normalised attention.

The study does not mean a pupil test can diagnose ADHD. Diagnosis depends on clinical assessment, developmental history and behaviour. The research had a small sample and laboratory setting. The group difference was not statistically significant after correction for multiple comparisons.

Researchers say larger studies are needed to determine whether pupil patterns can reliably help understand ADHD.

REFERENCE: Yadav, S., Aadya & Shukla, J. Trial-level pupil dynamics reflect attention-related variability and medication-associated modulation in ADHD. Sci Rep (2026). https://doi.org/10.1038/s41598-026-68871-2