| Summary: | Sensation seeking involves a desire to seek out thrilling experiences and a willingness to take risks in exchange for rewards. Sensation seekers are drawn to risky activities and high-risk sports represent potentially positive outlets for such individuals. Sensation seeking is moderately heritable and variants in genes involved in dopaminergic transmission have been associated with sensation-seeking phenotypes, although no studies have investigated personality and genetic variants in high-risk sport practitioners. This interdisciplinary dissertation explores personality (general sensation seeking and contextual sensation seeking in sport) and genetic variables (polymorphisms in monoamine pathway genes) in proficient high-risk sport practitioners. In the first series of projects two independent cohorts (n = 220, n = 668) of skiers/snowboarders (risky, yet popular sports) completed questionnaires and provided DNA samples. Data derived from questionnaires were used to evaluate the reliability and predictive validity of a new sensation-seeking tool for downhill sports that was developed as part of this study. The questionnaire showed strong psychometric properties and significantly predicted injury (β = .358, p < .001) in skiers and was used to define phenotypes in subsequent genetic studies. Using designs that employed independent replications, the newly defined phenotype was significantly associated (p < .001) with a functional variant (-521C/T) in the dopamine-4-receptor gene (DRD4), and an association between general sensation seeking and a variant (rs167771, intronic G/A) in the dopamine-3-receptor gene (DRD3) was also observed in the ski cohorts (p = .004). Personality and genetic variables were then compared using a quasi case-control design between practitioners of very high-risk (e.g., paragliding, ski-mountaineering, n = 141) and low-risk sports (e.g., running, n =132). The high-risk group scored higher than low-risk athletes on sensation seeking (p < .05), but not impulsivity, a trait commonly associated with deviant risk-taking and there were marginal associations between sport group and genetic variants in the stathmin (p = .004) and brain-derived neurotrophic factor (p = .03) genes, but the associations did not survive correction for multiple testing. The finding that risk-taking through sport may be, in part, predicted by genetic background provides a novel insight into the potential antecedents of performance. === Education, Faculty of === Kinesiology, School of === Graduate
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