Eyes may hold a physiological clue to ADHD, new study suggests

By isabelle // 2026-09-15

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Indian researchers found unmedicated children with ADHD show 23% greater pupil variability than children without the condition
The study analyzed eye-tracking data from 50 Chilean children performing a memory task 160 times
Pupil patterns shifted when children took their ADHD medication but researchers could not confirm it truly improved attention
The key statistical comparison narrowly missed significance and researchers stress pupil tracking is not a diagnostic tool
Scientists say larger, longer-term studies are needed before eye tracking could support ADHD diagnosis

Researchers at the Indraprastha Institute of Information Technology Delhi have identified a subtle but measurable difference in how the pupils of children with attention deficit hyperactivity disorder respond during cognitive tasks, a finding they say could eventually complement how the condition is diagnosed. In a study published in Scientific Reports, the research team reanalyzed eye-tracking data from 50 Chilean children ages 10 to 12. Of those, 28 had a combined-type ADHD diagnosis and 22 had none. Unmedicated children with ADHD showed approximately 23 percent greater trial-to-trial pupil variability than their peers without the condition, suggesting the eyes may reflect underlying differences in how attention fluctuates moment to moment.

How pupil measurements differed between ADHD and control groups

The children completed a working memory exercise: they watched dots appear on a grid, tried to remember their positions while ignoring a distracting image, and then judged whether a new dot matched a previously seen spot. Each child ran through the exercise 160 times, with an eye tracker sampling pupil size a thousand times per second throughout. After adjusting for each child's age, IQ, and the task's difficulty, the statistical model found unmedicated children with ADHD showed notably more variation in pupil responses from one trial to the next than controls. Within individual trials, though, their pupil responses fluctuated less, suggesting the two measures may be picking up on different underlying processes.

Medication effects showed pupil changes but not proof of normalization

Among the ADHD group, 17 children completed the task twice: once after a 24-hour pause in methylphenidate, and again while taking their usual dose. Their pupils reacted more strongly to the task while medicated and swung less from trial to trial, with overall response patterns resembling those of the control group. First author and computer scientist Saumya Yadav cautioned against interpreting this as evidence that medication normalized attention. "We could not completely separate these pharmacological effects from cognitive effects," Yadav said. Because methylphenidate itself acts on the body's pupil-control systems, the researchers said they could not tell how much of the change reflected sharper attention versus the drug simply doing its job physically. Researchers lacked data on each child's dosage or drug formulation, and the two sessions were roughly six months apart, which is enough time for typical development or practice effects to play a role.

Warning against premature diagnostic claims

The study does not yet support using pupil tracking as a clinical diagnostic tool. A statistical model built on thousands of individual trials picked up the group-level difference, but the direct comparison between participants fell just short of significance once adjusted for multiple comparisons. Lower accuracy on the memory task did track with greater pupil variability among unmedicated children with ADHD, though not meaningfully more than in the control group. "It is still too early to consider pupil measurements as a clinical diagnostic tool," Yadav emphasized. The small sample size, reliance on existing data, and controlled laboratory setting limit how far the findings can be generalized; a real classroom is far more unpredictable than a lab. Polish researchers presenting at the 2026 European Society of Cataract and Refractive Surgeons meeting in London echoed similar caution. Sylwia Kijewska of the Polish Optometric Association noted that while various ocular measurement modalities show promise, "ocular standalone diagnosis still remains in the area of science-fiction."

Larger studies needed before practical applications emerge

The Indian team said bigger, independent, longer-term studies are needed to determine whether these pupil patterns hold up across different populations and everyday settings. If confirmed, eye tracking might complement existing diagnostic methods, potentially giving clinicians another way to track whether a child's attention is shifting over time or responding to treatment. For parents already navigating stimulant treatment, the study underscores how much remains unsettled about what methylphenidate does inside a developing brain, and how rarely that uncertainty makes it into a brief prescription conversation. Until researchers can separate a drug's physiological footprint from any real gain in attention, families deserve that ambiguity spelled out plainly, not smoothed over by a pupil scan or a prescription pad. Sources for this article include: ScienceAlert.com OphthalmologyTimes.com MedicalDialogues.in