Background: Recent evidence suggests that there may be long-term effects of concussion that occur from participation in contact sports. However, little is known about the long-term effects of participating in contact sports. Purpose: The purpose of this dissertation was to 1) to retrospectively compare neurocognitive performance in healthy student-athletes participating in high and moderate levels of contact sports between two seasons of participation, 2) retrospectively compare neurocognitive function in healthy college football athletes participating in high- and low-risk positions two between two seasons of participation, and 3) to compare neurocognitive function, inhibitory control, and single- and dual-task steady-state and tandem gait characteristics between former high school contact sport athletes and control adults. Methods: For study 1 and 2 a total of 294 high school athletes (high contact sport: n = 142, moderate contact sport: n = 152) and a total of 80 college football athletes (high-risk position: n = 37, low-risk position: n = 43) completed a baseline neurocognitive assessment at two separate occasions on average two years apart, respectively. For study 3, a final sample of 39 adults (former contact sport athletes: n = 27, controls: n = 12) completed a demographics questionnaire, a neurocognitive assessment, a modified version of the flanker task, and a gait assessment including steady-state and tandem gait during single- and dual-tasks conditions. Results: For study 1, indicated there were no significant interactions between the two baseline administrations and contact levels, and no significant improvements in composite scores over time in high school athletes. There were significant differences between high school contact levels for Visual-Motor Speed and Reaction Time. For study 2, college football athletes in the high-risk positions had worse Reaction Time that improved over time, compared to the low-risk for repetitive head impact exposure group. There were no significant differences for any other composite score. Finally, for study 3, there were no significant differences in neurocognitive function, inhibitory control, or gait characteristics between adult former contact sport athletes and controls when adjusting for previous history of concussion. Conclusions: High school athletes participating in high contact sports demonstrated worse scores for Visual-Motor Speed and Reaction Time. College football athletes participating in high-risk positions demonstrated small, but slower reaction times that improved between test administrations compared to the low-risk group. However, adults with former high school contact sport participation for at least two years did not demonstrate worse neurocognitive function, inhibitory control, or any gait characteristic when compared to adults that never participated in contact sports. Future research should continue to investigate the manifestation or progression of declines in cognition or postural control of former high school contact sport athletes' years after high school contact sport participation.
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