Regional cerebral perfusion in patients with Alzheimer's disease and mild cognitive impairment: effect of APOE Epsilon4 allele

The objective of this study was to evaluate the effect of apolipoprotein E (APOE) epsilon 4 allele on regional cerebral perfusion (rCBF) changes using arterial spin labeling (ASL) magnetic resonance imaging (MRI) in subjects who are carriers or noncarriers of this risk factor for Alzheimer disease (AD). Twenty-five subjects with AD, 25 with amnestic mild cognitive impairment (MCI) and 25 cognitively normal (CN) subjects underwent isotropic volumetric T1-weighted imaging and pulsed ASL MRI. All subjects were divided into carrier or noncarriers of the epsilon4 allele. Voxel-based statistical analyses were performed among groups on rCBF by ANOVA tests. In each subject group, we also evaluated the rCBF change between carrier and noncarrier groups. rCBF was significantly reduced in AD subjects compared to other subjects. In CN and AD subjects, rCBF in the carrier group was significantly reduced in several areas of the brain compared with that of the noncarrier group. In the carrier group, rCBF was significantly increased in the right parahippocampal gyrus, the bilateral cingulate gyri and the right posterior cingulate on the MCI group in addition to the right superior frontal gyrus in the AD group. rCBF in the CN and AD groups were significantly reduced in the subjects with the carriers of the epsilon4 allele, which is a risk factor for Alzheimer's disease. In addition, rCBF in the MCI group was significantly increased in subjects who were carriers. Therefore, rCBF can be used as a biomarker to show disease progression in areas of the brain of MCI subjects.