Chronic exposure to head impacts is linked to later susceptibility for serious neuropsychiatric conditions including depression, Alzheimer's disease, Parkinson's disease, and Chronic Traumatic Encephalopathy (CTE). Most athletes who participate in collision sports (e.g. American football, ice hockey, rugby, etc.) sustain many head impacts over the course of an athletic season. The majority of impacts are classified as subconcussive impacts, defined as direct or indirect blows to the head that do not result in observable acute symptoms but nonetheless compromise axonal integrity and may have an adverse cumulative effect over time. Cross-sectional studies of former high school, collegiate, and professional collision sport athletes demonstrate impairments in cognition, neural structure, and neural function associated with the accumulation of subconcussive impacts. Prospective, longitudinal (e.g. pre- to post-season) studies of collision sport-athletes demonstrate structural and functional neural changes associated with subconcussive impacts but have not consistently demonstrated cognitive changes over this timeframe. There is a high probability, however, the cognitive measures currently used in the literature to detect change associated with subconcussive impacts lack adequate sensitivity. Alternatively, laboratory based eye movement testing shows promising sensitivity for reliably detecting neurocognitive change associated with head trauma. Established experimental eye movement paradigms allow for reliable assessment of executive cognitive abilities, such as attentional control and working memory. Many brain regions involved in the control of eye movements are associated with pathophysiological changes following symptomatic concussion. Therefore, eye movement testing is aptly suited to detect change associated with accumulated subconcussive impacts. The purpose of the proposed project is to assess the ability of eye movement testing to detect change associated with subconcussive impacts sustained over a collision-sports season (ice hockey) among collegiate athletes. Pre- to post-season change observed on eye movement testing will be compared to change observed on ImPACT (Immediate Post-Concussion Assessment and Cognitive Testing), the computerized cognitive measure most commonly used in the literature. Non-collision sport athletes studied over a similar period will serve as a control group. Completing this project will improve scientific knowledge regarding neurocognitive consequences associated with subconcussive impacts and the methodological validity of eye movement testing to detect change associated with subconcussive impact exposure. This work will provide the foundation to launch important future research regarding dose effects of subconcussive impacts and the use of eye movement testing to track and predict long-term adverse change associated with subconcussive impacts.

Public Health Relevance

Chronic exposure to head impacts via participation in collision sports may have serious adverse neuropsychiatric and neurodegenerative consequences later in life. While neuroimaging can detect acute neurofunctional and neurostructural changes in the brain as a result of exposure to subconcussive head impacts, there is currently no reliable and sensitive measure available that successfully detects the subtle cognitive and sensorimotor changes thought to be associated with subconcussive impacts, which may accumulate over time and yield adverse functional outcomes. This study aims to pilot eye movement testing as a reliable and sensitive measure of cognitive and sensorimotor change associated with accumulated subconcussive impacts over the sports season; by identifying a reliable technology to measure these changes, we will lay the foundation for future research, including: a) determining developmental periods of sensitivity in which subconcussive impacts have more adverse or consequential effects on neurocognition; b) assessing the dose dependent effects (i.e., amount of exposure) of subconcussive impacts and neurocognitive change; and c) structural brain correlates of neurocognitive change associated with subconcussive exposure.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Predoctoral Individual National Research Service Award (F31)
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Special Emphasis Panel (ZRG1)
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Bellgowan, Patrick S F
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Northwestern University at Chicago
Schools of Medicine
United States
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