For generations, the diagnosis of ADHD has rested on the uncertain ground of behavioral observation — a process shaped as much by circumstance and perception as by the condition itself. Now, researchers across multiple institutions have identified a measurable pattern in eye movement that appears consistently in people with ADHD, offering what may become the first reliable biological foothold in a field long searching for one. The discovery does not yet change clinical practice, but it gestures toward a future in which the mind's struggles leave a legible trace in the body — one that can be re