Objective To investigate the relationship between personality traits and Catechol O-methyltransferase (COMT) rs4680 genotypewith concussion history in rugby players.

Design Case-control study.

Setting High school, amateur, and professional rugby teams in South Africa.

Participants Participants were excluded if they reported a previous brain-related medical condition or a non rugby-related concussion, or were not of European ancestry. Three hundred and one participants were included in the study. Based on self-reported concussion history (30 suspected concussion cases were excluded), participants were grouped into the control (non-concussed, n=140) or case group (one or more diagnosed concussions, n=131).

Assessment of risk factors Participants completed a concussion history questionnaire, Cloninger’s Tridimensional Personality Questionnaire (TPQ) and all DNA samples were genotyped for COMT rs4680. Logistic regression, co-varying for age, was used to determine differences in genotype frequencies. A one-way analysis of variance was used to compare TPQ dimension (novelty seeking, harm avoidance, and reward dependence) scores.

Outcome measures COMT rs4680 genotype frequencies and TPQ scores.

Main results The COMT rs4680 VV genotype was overrepresented in the controlgroup when all participants were combined (p=0.030, OR: 1.89, 95% CI: 1.05 – 3.45; control: 31%, cases: 18%) and whenonly school participants were analysed (p=0.009, OR: 3.23, 95% CI: 1.27 – 8.33; control:37%, cases:15%). Furthermore, the schoolcontrol group had higher harm avoidance scores compared to cases (p=0.004), andthe VV genotype was associated with increased harm avoidance subscale 1 scores (p=0.023).

Conclusions This study provides preliminary indication that personality traits, and associated genetic variants, can influence concussion in rugby.

Competing interests None.