Browsing by Author "Shah, Alok S."

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    Association between Preseason/Regular Season Head Impact Exposure and Concussion Incidence in NCAA Football
    (ACSM, 2022-06) Stemper, Brian D.; Harezlak, Jaroslaw; Shah, Alok S.; Rowson, Steven; Mihalik, Jason P.; Riggen, Larry; Duma, Stefan; Pasquina, Paul; Broglio, Steven P.; Mcallister, Thomas W.; Mccrea, Michael A.; CARE Consortium Investigators; Psychiatry, School of Medicine
    Purpose Contact sport athletes are exposed to a unique environment where they sustain repeated head impacts throughout the season and can sustain hundreds of head impacts over a few months. Accordingly, recent studies outlined the role that head impact exposure (HIE) has in concussion biomechanics and in the development of cognitive and brain-based changes. Those studies focused on time-bound effects by quantifying exposure leading up to the concussion, or cognitive changes after a season in which athletes had high HIE. However, HIE may have a more prolonged effect. This study identified associations between HIE and concussion incidence during different periods of the college football fall season. Methods This study included 1120 athlete seasons from six National Collegiate Athletic Association Division I football programs across 5 yr. Athletes were instrumented with the Head Impact Telemetry System to record daily HIE. The analysis quantified associations of preseason/regular season/total season concussion incidence with HIE during those periods. Results Strong associations were identified between HIE and concussion incidence during different periods of the season. Preseason HIE was associated with preseason and total season concussion incidence, and total season HIE was associated with total season concussion incidence. Conclusions These findings demonstrate a prolonged effect of HIE on concussion risk, wherein elevated preseason HIE was associated with higher concussion risk both during the preseason and throughout the entire fall season. This investigation is the first to provide evidence supporting the hypothesis of a relationship between elevated HIE during the college football preseason and a sustained decreased tolerance for concussion throughout that season.
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    Comparison of Head Impact Exposure Between Concussed Football Athletes and Matched Controls: Evidence for a Possible Second Mechanism of Sport-Related Concussion
    (Springer, 2018) Stemper, Brian D.; Shah, Alok S.; Harezlak, Jaroslaw; Rowson, Steven; Mihalik, Jason P.; Duma, Stefan M.; Riggen, Larry D.; Brooks, Alison; Cameron, Kenneth L.; Campbell, Darren; DiFiori, John P.; Giza, Christopher C.; Guskiewicz, Kevin M.; Jackson, Jonathan; McGinty, Gerald T.; Svoboda, Steven J.; McAllister, Thomas W.; Broglio, Steven P.; McCrea, Michael; Psychiatry, School of Medicine
    Studies of football athletes have implicated repetitive head impact exposure in the onset of cognitive and brain structural changes, even in the absence of diagnosed concussion. Those studies imply accumulating damage from successive head impacts reduces tolerance and increases risk for concussion. Support for this premise is that biomechanics of head impacts resulting in concussion are often not remarkable when compared to impacts sustained by athletes without diagnosed concussion. Accordingly, this analysis quantified repetitive head impact exposure in a cohort of 50 concussed NCAA Division I FBS college football athletes compared to controls that were matched for team and position group. The analysis quantified the number of head impacts and risk weighted exposure both on the day of injury and for the season to the date of injury. 43% of concussed athletes had the most severe head impact exposure on the day of injury compared to their matched control group and 46% of concussed athletes had the most severe head impact exposure for the season to the date of injury compared to their matched control group. When accounting for date of injury or season to date of injury, 72% of all concussed athletes had the most or second most severe head impact exposure compared to their matched control group. These trends associating cumulative head impact exposure with concussion onset were stronger for athletes that participated in a greater number of contact activities. For example, 77% of athletes that participated in ten or more days of contact activities had greater head impact exposure than their matched control group. This unique analysis provided further evidence for the role of repetitive head impact exposure as a predisposing factor for the onset of concussion. The clinical implication of these findings supports contemporary trends of limiting head impact exposure for college football athletes during practice activities in an effort to also reduce risk of concussive injury.
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    Role of Repetitive Head Impact Exposure in the Onset of Concussion: Evidence of a Possible Second Mechanism of Concussion for Contact Sports
    (International Research Council on the Biomechanics of Injury, 2018-09) Stemper, Brian D.; Shah, Alok S.; Wild, Alexa; Humm, John R.; Pintar, Frank A.; Broglio, Steven P.; McAllister, Thomas W.; McCrea, Michael; Psychiatry, School of Medicine
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    Time Delta Head Impact Frequency: An Analysis on Head Impact Exposure in the Lead Up to a Concussion: Findings from the NCAA-DOD Care Consortium
    (Springer, 2022-08-06) Seifert, Jack; Shah, Alok S.; Harezlak, Jaroslaw; Rowson, Steven; Mihali, Jason P.; Riggen, Larry; Duma, Stefan; Brooks, Alison; Cameron, Kenneth L.; Giza, Christopher C.; Goldman, Joshua; Guskiewicz, Kevin M.; Houston, Megan N.; Jackson, Jonathan C.; McGinty, Gerald; Pasquina, Paul; Broglio, Steven P.; McAllister, Thomas W.; McCrea, Michael A.; Stemper, Brian D.; Epidemiology, Richard M. Fairbanks School of Public Health
    Sport-related concussions can result from a single high magnitude impact that generates concussive symptoms, repeated subconcussive head impacts aggregating to generate concussive symptoms, or a combined effect from the two mechanisms. The array of symptoms produced by these mechanisms may be clinically interpreted as a sport-related concussion. It was hypothesized that head impact exposure resulting in concussion is influenced by severity, total number, and frequency of subconcussive head impacts. The influence of total number and magnitude of impacts was previously explored, but frequency was investigated to a lesser degree. In this analysis, head impact frequency was investigated over a new metric called ‘time delta’, the time difference from the first recorded head impact of the day until the concussive impact. Four exposure metrics were analyzed over the time delta to determine whether frequency of head impact exposure was greater for athletes on their concussion date relative to other dates of contact participation. Those metrics included head impact frequency, head impact accrual rate, risk weighted exposure (RWE), and RWE accrual rate. Athletes experienced an elevated median number of impacts, RWE, and RWE accrual rate over the time delta on their concussion date compared to non-injury sessions. This finding suggests elevated frequency of head impact exposure on the concussion date compared to other dates that may precipitate the onset of concussion.