Carriers of the ApoE-ε4 allele, representing 15–20% of the population, show higher risk of developing AD (Farrer et al., 1997), and physical activity was shown to improve cognition in non-ε4 carriers, but not in ε4 carriers, demonstrating the importance to discriminate both populations (Obisesan et al., 2012). The gene discussed is APOE; the disease is Alzheimer disease.