Chronic levels of physical activity have been associated with increased dopamine (D2) receptors resulting in increased sensitivity to dopamine release. The catechol-O-methyltransferase enzyme, responsible for dopamine degradation, contains a functional polymorphism, which plays an important role in dopamine regulation within the prefrontal cortex. This polymorphism has previously been shown to affect human cognition and personality. However, the effect of this polymorphism has not been shown in ultra-endurance athletes.
Aim: To examine the association of the COMT val(158)met variant with personality traits (harm avoidance, novelty seeking, reward dependence, resilience) and psychological distress (K10) of habitual physically active Ironman athletes compared to recreationally active controls.
Methods: 51 ultra-endurance Ironman athletes and 56 recreationally active controls were genotyped for the catechol-O-methyltransferase val(158)met polymorphism. Of the 107 participants, 55 ultra-endurance athletes and 32 recreationally active controls completed online personality questionnaires (harm avoidance, novelty seeking, reward dependence, resilience) and a psychological distress questionnaire (K10).
Results: The personality trait, harm avoidance (p=0.001) and psychological distress (p=0.003) were significantly lower in Ironman athlete participants. Novelty seeking was significantly higher (p=0.02) in Ironman athlete participants with a significantly higher (p=0.04) score in Met(158) homozygous allele carriers.
Conclusion: Chronic levels of physical activity, as seen in ultra-endurance athletes, show increased novelty seeking scores in Met(158) homozygous allele carriers.
Keywords: Behavior; Catechol-o-methyltransferase; Novelty seeking; Ultra-endurance.
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