PURPOSE: Currently, the long-term effects of concussions are not fully understood. Some research has demonstrated continued decrements in neurocognitive performance in both pediatric and adult populations, including memory tasks, in those athletes with a history of multiple concussions. With implicit memory, an individual will know how to complete a task, but may be unaware of this knowledge. While much research has been conducted on the relationship between physical activity (PA) and improved performance on tasks of explicit memory and executive function, no research currently has explored PA and implicit memory. Therefore, it is appropriate to consider the role PA may have in the relationship between concussion history and performance on a cognitive task of implicit memory. The purpose of this dissertation was to examine the differences in scores of implicit memory acquisition across concussion history groups (i.e., no concussion, one or more previous concussion(s)) and across current levels of PA. METHODS: The study design was cross-sectional. The independent variables were concussion history and PA. The dependent variable was a measure of implicit memory acquisition. All participants were high school athletes, both male and female, between the ages of 13 and 19 years. Athletes were grouped together based on their concussion histories (i.e., no previous concussion, one or more previous concussion(s)). PA was assessed by the Physical Activity Questionnaire for Adolescents (PAQ-A) and scored as a continuous variable, resulting in a score of one to five. Implicit memory was measured using the Serial Reaction Time Task (SRTT). Demographic variables including age, height, weight, sex, race/ethnicity, and approximate grade point average, as well as concussion history, were obtained via a demographic form completed by the participant. RESULTS: A total of 64 high school athletes (29 female, 35 male) participated in the current study, 46 (25 female, 21 male) had no history of concussion, compared to 18 athletes (4 female, 14 male) with a history of at least one previous concussion. Overall, the findings suggested a history of concussion was not related to implicit memory acquisition in adolescents, F(1,50) = .250, p = .619, adj. R2 = .015. Furthermore, current PA was not significantly related to performance on the SRTT (F(1,48) = 1.543, p = .220, adj. R2 = .011). Finally, there was no interaction of concussion history and PA relative to implicit memory. DISCUSSION: While previous research has demonstrated deficits in implicit memory acquisition in previously concussed, asymptomatic adults, the current study did not replicate these results in an adolescent population. Additionally, implicit memory was not associated with current PA. These findings suggest, in adolescents, concussions may not be associated with implicit memory acquisition.
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