APOE and Alzheimer disease: Interestingly, ApoE4-carriers (i.e. carriers of a specific genotype variant of the apolipoprotein polymorphism) are more susceptible to concussion-mediated AD-risk, which is in line with the experimental observation that ApoE4, in contrast to ApoE2 and ApoE3, makes particularly the BBB more vulnerable to proinflammatory insults.