While numerous groups have reported that APOE4+ AD patients do in fact experience a more accelerated cognitive decline compared to APOE4− AD patients [15–20], other studies have shown either no APOE genotype-associated differences in the rate of cognitive decline in AD patients [21–27] or slower cognitive decline in APOE4+ vs. APOE4− AD patients [28–30] (Table 1). The gene discussed is APOE; the disease is Mental deterioration.