The apolipoprotein E (APOE) gene e4 allele is a genetic risk factor for late-onset familial and sporadic Alzheimer's disease (AD). The change in size of the whole brain or total ventricular system did not differ significantly among APOE genotypes. The patients with e3/e4 or e4/e4 genotype (e4+ group), however, exhibited severe atrophy in the inferior temporal lobe, while those with e3/e3 genotype (e4- group) showed mild atrophy. Regional cerebral blood flow (rCBF) in the cerebral cortex, particularly in the temporal lobe, was lower in the e4+ group than in the e4- group. These results indicate that possession, and thus expression, of the APOE e4 allele preferentially affects the inferior temporal lobe, encompassing the hippocampus and amygdala, in AD patients
