Does the Apolipoprotein ε4 Allele Predispose Varsity Athletes to Concussion? A Prospective Cohort Study

OBJECTIVE: To determine the association between the apolipoprotein epsilon 4 allele and concussion. We hypothesized that apolipoprotein epsilon 4 carriers may be more likely to sustain a concussion. DESIGN: Prospective cohort study. SETTING: University of Toronto varsity athletics. PARTICIPANTS: Included 318 of 822 collegiate student athletes who participated in University of Toronto varsity sports from September 2002 to April 2006. ASSESSMENT OF RISK FACTORS: The presence of apolipoprotein epsilon 4 was described dichotomously after genotyping blood samples collected from participants. MAIN OUTCOME MEASUREMENTS: Concussions were identified by sport-medicine professionals present on the sidelines using on-field assessment forms. All concussion diagnoses were verified by a sports medicine physician. Survival analysis was used to determine the association between apolipoprotein epsilon 4 and first concussion. RESULTS: The unadjusted hazard ratio for concussion in the apolipoprotein epsilon 4 carriers was 1.18 (95% CI: 0.52, 2.69) compared to noncarriers. Adjustment for sex, weight, height, and team type resulted in a hazard ratio of 1.06 (95% CI: 0.41, 2.72), indicating little effect from confounding factors. CONCLUSIONS: There is no important association between carrying the apolipoprotein epsilon 4 allele and sustaining a concussion. At this time, we do not recommend preseason genetic testing for varsity athletes as a mechanism for targeting prevention strategies.