Summary: Can a single concussion from your youth still affect your brain ten or twenty years later? A new study suggests the answer is yes.
Researchers used advanced eye-tracking technology to show that people who suffered concussions more than a decade ago still exhibit significant “neurological “lag” in how their eyes track moving objects. These subtle deficits, invisible to the naked eye or standard clinical exams, indicate that the brain’s “internal map” for movement and timing may never fully reset after a traumatic brain injury (TBI).
Key Facts
- The “Lag” Discovery: Participants with a history of concussions showed a delayed reaction in “pursuit eye movements”—the ability to smoothly follow a moving target.
- Decades of Impact: The neurological deficits were present in individuals whose last head injury occurred over 10 to 15 years ago, suggesting that some post-concussion changes are permanent.
- Beyond Standard Tests: These patients often passed traditional cognitive and physical exams, but the high-speed eye-tracking revealed “micro-stutters” in brain-to-eye communication.
- Brainstem & Cerebellum: The researchers believe the trauma affects long-term signaling in the brainstem and cerebellum, regions responsible for fine motor control and predictive timing.
- Predictive Tool: This study positions eye-tracking as a powerful, non-invasive biomarker for “hidden” brain trauma and could help identify those at higher risk for neurodegenerative diseases later in life.
Source: University of Colorado
A study from researchers at the CU Anschutz Marcus Institute for Brain Health suggests that veterans with concussions may continue to show subtle but measurable brain function differences more than a decade after their injury.
Researchers found these differences can be detected through specialized eye movement testing.
The findings were recently published in the Journal of Neuro-Ophthalmology.
Mild traumatic brain injuries are common among military service members and occur in athletes and civilians through sports impacts, car accidents and falls. While most individuals recover within weeks or months, the new research indicates that some may experience lingering changes in attention, processing speed and impulse control long after symptoms appear to resolve.
Eye Movements Reveal Subtle Brain Changes
“The eyes are directly connected to brain networks that control attention, information processing and decision-making,” said the study’s lead investigator Jeffrey Hebert, PhD, PT, associate professor at the CU Anschutz School of Medicine and director of research for the CU Anschutz Marcus Institute for Brain Health.
“By studying how someone’s eyes move during a cognitively demanding task, we can detect subtle brain changes that might not appear on a standard bedside exam or brain scan.”
The study evaluated 78 military veterans, including 38 with a history of mild traumatic brain injury and 40 without. Participants completed a series of eye movement tasks and cognitive tests designed to measure executive function of attention, processing speed and self-control.
Researchers found that veterans with prior concussions were more likely to demonstrate slower and less accurate eye movements along with reduced performance on certain attention-based tasks. Some of these differences were still measurable more than 10 years after the original injury.
Hebert said eye movements rely on complex networks across multiple regions of the brain. Tasks that require individuals to quickly look away from a visual target and tasks that require rapid visual recognition and verbalization of a viewed object test not only visual function but also cognitive control.
This includes the ability to focus, suppress impulses and respond quickly and accurately. Because these processes depend on widespread neural connections, several mild injuries may leave lasting but difficult to detect effects.
“Even when someone feels recovered, their brain may still be working differently behind the scenes, especially during visually demanding tasks and in busy environments” Hebert said. “Objective eye movement testing gives us a measurable way to assess these often covert problems.”
Implications for Concussion Care
The findings could have important implications for long term concussion care.
“Standard imaging tools such as MRI scans often appear normal after mild brain injury, making persistent symptoms difficult to verify objectively,” Hebert said. “Cognitively challenging eye movement assessments may provide clinicians with an additional tool to better understand ongoing cognitive concerns and more precisely tailor rehabilitation strategies.
Although the study focused on military veterans, the results may apply more broadly to athletes, first responders and civilians who have experienced concussions.
The team emphasizes that most individuals recover well from mild traumatic brain injury. However, identifying those who continue to experience subtle effects could improve follow up care, long term monitoring and treatment planning optimizing healthier brain adaptation.
Future studies will explore whether incorporating cognitively challenging eye movement testing into routine concussion evaluations could help clinicians better identify traumatic brain injury, track recovery and guide treatment decisions.
Funding: The research was funded by the Congressionally Directed Medical Research Programs, U.S. Army Medical Research Acquisition Activity, Department of Defense, Vision Research Program Award.
Key Questions Answered:
A: Not necessarily. The “lag” found in this study is often imperceptible in daily life because the brain is incredibly good at compensating. However, it shows that the injury left a permanent “fingerprint” on your neural wiring. It’s a reminder to be extra protective of your head health as you age.
A: Tracking a moving object is one of the most complex tasks the brain performs. it requires perfect synchronization between your vision, your balance (vestibular system), and your motor control. If there is a “hitch” in the brain’s wiring anywhere, an eye test will catch it before almost any other exam.
A: Absolutely. Current “sideline” tests are often subjective. High-speed eye-tracking provides objective, mathematical data. If we know your “baseline” eye speed, we can tell instantly if a new hit has caused a disruption in your neural pathways.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this eye tracking and TBI research news
Author: Laura Kelley
Source: University of Colorado
Contact: Laura Kelley – University of Colorado
Image: The image is credited to Neuroscience News
Original Research: Closed access.
“Ocular Motor Control and Cognitive Function in Military Veterans With Chronic Mild Traumatic Brain Injury” by Hebert, Jeffrey R. PhD, PT; Wagner, Brandie D. PhD; Filley, Christopher M. MD; Crowder, Kayla L. PT, DPT, NCS; Rubinstein, David MD; McNamara, Stephen M. OD; Johnston-Brooks, Catharine H. PhD; Karki, Ramesh MS; McCann, Ashley V. PT, DPT, NCS; Subramanian, Prem S. MD, PhD. Journal of Neuro-Ophthalmology
DOI:10.1097/WNO.0000000000002435
Abstract
Ocular Motor Control and Cognitive Function in Military Veterans With Chronic Mild Traumatic Brain Injury
Background:
Ocular motor control (OMC) and cognitive dysfunction are common persistent sequelae in persons with mild traumatic brain injury (mTBI). Combat and training operations frequently expose military Service Members to biomechanical and blast events that render them susceptible to mTBI, and problems such as OMC disturbances and cognitive dysfunction are frequent long after injury.
However, these problems can be difficult to detect, often only becoming clinically evident with physical or psychological stress. Knowledge of the relationship between OMC and cognitive dysfunction in chronic mTBI, and of clinical tools to assess this issue, is limited.
Methods:
Setting: Academic laboratory; Marcus Institute for Brain Health, University of Colorado; Design: 2-arm, examiner-blinded cross-sectional observational study. Participants: Military Veterans with chronic mTBI (experimental; n = 38) whose most recent mTBI was more than 3 months before enrolment, and Veterans without a history of TBI (control; n = 40); Measures: The computerized King-Devick (K-D) test assessed rapid number naming tasks; the Right Eye computerized eye tracker system measured antisaccade tasks; the Conners’ Continuous Performance Test (CPT) tested aspects of selective and sustained attention and impulsivity; the FAS test measured the ability to name as many common nouns that start with “F,” “A,” and “S” as a method to assess phonemic verbal fluency, attention, and initiation; and the Posttraumatic Stress Disorder (PTSD) Checklist for DSM-5 (PCL-5) was used as a self-report of posttraumatic stress-related symptoms.
Results:
Veterans in the experimental group had a median of 2 mTBIs, and these occurred approximately 11 years before the study. On the K-D Test, the experimental group had significantly more errors and took significantly more time (51.32 seconds) compared with the control group (43.00 seconds).
Significantly greater antisaccade latencies were found in the experimental group for target only, on target distractor, and ipsilateral proximal distractor paradigms, and antisaccade error rates were significantly greater in the experimental group for the contralateral proximal distractor paradigm. Significantly greater PCL-5, and worse FAS test scores and CPT commissions and omissions scores were found in the experimental group. For the experimental group, time since most recent TBI correlated with antisaccade on target distractor error rates.
Regression modeling showed that FAS test scores were a significant determinant of K-D test performance. Separate regression modeling for each of the antisaccade task paradigms indicated that group status was significantly associated with antisaccade latency scores for the ipsilateral proximal distractor paradigm.
PCL-5 was a significant factor for the on target distractor paradigm, and age and cognitive function denoted by FAS test and CPT scores were significant factors contributing to error rates in multiple specified antisaccade paradigm task performances.
Conclusions:
Results support the conclusion that OMC and cognitive performance are persistent co-occurring problems in Veterans with chronic mTBI. Notably, these deficits can be detected even after as few as 2 mTBIs that occurred 11 years earlier, indicating that an OMC-cognition axis of sequelae may exist in the chronic stage of mTBI. The results also identify cognitive correlates of the OMC task paradigms, aiding in the clinical application and interpretation of these tests in chronic mTBI.
