The APOE ε4 allele can also have an additive effect on LOAD-associated brain glucose hypometabolism (Ossenkoppele et al., 2013; Reiman et al., 2005), as this allele contributes to glucose hypometabolism even in the absence of neurodegeneration and cognitive decline (Knopman et al., 2014; Sundermann et al., 2018). The gene discussed is APOE; the disease is Mental deterioration.