Browsing by Author "Tabor, Jason Benjamin"

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    The Effects of Anabolic-Androgenic Steroids on Repetitive Mild Traumatic Brain Injury Outcomes
    (2019-08-16) Tabor, Jason Benjamin; Mychasiuk, Richelle; Yeates, Keith Owen; Spanswick, Simon C.; Shultz, Sandy R.; Debert, Chantel Teresa; Pittman, Quentin J.
    Given the considerable prevalence of AAS abuse and RmTBI incidence in adolescents and their overlapping symptomology, the goal of this research was to characterize any cumulative behavioural and neuropathological outcomes of AAS on the concussed brain in adolescent Sprague Dawley rats. Although there were minimal effects of AAS on RmTBI outcomes, we identified cumulative effects of RmTBI and abrupt AAS and exercise cessation on measures of anxiety, working memory, in addition to altered gene expression in the neural circuitry involved in the innate stress response. Additionally, we identified alarming effects of AAS on the developing brain; prefrontal cortex atrophy, amygdala hypertrophy, and damaged white matter in the corpus callosum were identified which were associated with changes in gene expression and subsequent behavioural impairments. The findings from this investigation provide valuable insight into the effects of AAS exposure on the developing brain in the context of RmTBI.
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    Plasma Biomarkers Associated with Sport-Related Concussion in Adolescents: Age and Sex Matter
    (2023-04-13) Tabor, Jason Benjamin; Emery, Carolyn; Debert, Chantel; Yeates, Keith; Esser, Michael; Wellington, Cheryl
    Adolescent sport-related concussion (SRC) is a growing public health concern. Relative to adult SRC, there exists a large gap in the literature concerning adolescents, with few studies focusing on blood biomarkers relevant to SRC. Multiple studies in this thesis aim to increase our understanding of how blood biomarkers associated with SRC may present in athletic adolescents. This thesis begins by reviewing the current landscape of SRC biomarkers (i.e., glial fibrillary acidic protein [GFAP], ubiquitin-c-terminal hydrolase L1 [UCH-L1], neurofilament light [NF-L], and tau) and their possible roles in clinical management. Limitations to the SRC biomarker literature precluding their progress towards clinical validation are also highlighted. The neuroinflammatory response to concussion is then discussed in more detail, emphasizing potential covariables that may influence SRC biomarkers. Plasma biomarker levels [GFAP, UCH-L1, NF-L, total tau (T-tau), and P-tau-181] are then characterized with respect to age, sex, and previous concussion in healthy adolescents. This thesis then discusses the impact of replicate error in biomarker measurements at low concentrations and explores multiple biostatistical approaches to optimizing statistical precision in biomarker data analysis. Finally, the associations between SRC and plasma biomarker levels are examined in adolescent sport participants to investigate whether biomarkers are sensitive to SRC at various timepoints throughout recovery. The collective work of this thesis demonstrates that multiple confounding variables may influence GFAP, UCH-L1, NF-L, and tau in adolescents. First, in healthy individuals, UCH-L1 and P-tau-181 differed by sex, and age was negatively associated with GFAP. Secondly, this thesis showed that varying levels of agreement in these biomarkers samples from these healthy adolescents warranted a multilevel modelling approach using both replicates in analysis (as opposed to excluding sample duplicates based on arbitrary variation thresholds) to produce optimally precise estimates of association. Lastly, the work herein provides evidence suggesting GFAP, UCH-L1, NF-L, and T-tau are sensitive to SRC at various times throughout recovery in adolescents. Furthermore, results emphasize the importance of analyzing these biomarkers with respect to age and sex. The findings presented in this thesis make a significant contribution to the field of adolescent SRC biomarkers and support their continued use for investigating adolescent SRC neuropathophysiology.