Tellingly, the ε-4 allele of the APOE (apolipoprotein E) gene, known first (Belloy et al., 2019) to predispose to the dementia known as Alzheimer’s, and then shown to exacerbate dementia pugilistica (Forstl et al., 2010), traumatic brain injury (TBI) in military veterans (Merritt et al., 2021) and chronic traumatic encephalopathy (Atherton et al., 2022), also exacerbates heading-related cognitive loss in soccer players (Hunter et al., 2020). This evidence concerns the gene APOE and dementia.