Lack of Influence of Apolipoprotein E Status on Cognition or Brain Structure in Professional Fighters.

The role of the apolipoprotein e4 allele in moderating cognitive and neuroanatomical degeneration following repeated traumatic brain injury is controversial. Here we sought to establish the presence or absence of such a moderating relationship in a prospective study of active and retired boxers and mixed martial arts fighters. Fighters (n = 193) underwent cognitive evaluations, interviews regarding fight history, MRI of the brain, and genetic testing. We used a series of moderator analyses to test for any relationship of apolipoprotein genotype on structural volumes of brain regions previously established to be smaller in those with the most fight exposure, and on cognitive abilities also established to be sensitive to fight exposure. No moderating relationship was detected in any of the analyses. The results of this study suggest that there is no impact of apolipoprotein genotype on the apparent negative association between exposure to professional fighting and brain structure volume or aspects of cognition.