Affiliations: Department of Radiology, 2nd Affiliated Hospital of Zhejiang University School of Medicine, China
Correspondence:
[*]
Correspondence to: Minming Zhang, Department of Radiology, 2nd Affiliated Hospital, Zhejiang University School of Medicine, No. 88 Jiefang Road, Shangcheng District, Hangzhou 310009, China. Tel./Fax: +86 057187315255; E-mail: zhangminming@zju.edu.cn.
Note: [1] Data used in preparation of this article were obtained from the Alzheimer’s disease Neuroimaging Initiative (ADNI) database (http://www.adni.loni.usc.edu). As such, the investigators within the ADNI contributed to the design and implementation of ADNI and/or provided data but did not participate in analysis or writing of this report. A complete listing of ADNI investigators can be found at: http://adni.loni.usc.edu/wp-content/uploads/how_to_apply/ADNI_Acknowledgement_List.pdf
Abstract: The apolipoprotein E (APOE) ɛ4 allele is the best-known genetic risk factor for developing sporadic Alzheimer’s disease (AD). According to neuroimaging studies, the APOE ɛ4 allele is associated with localized altered brain function. However, in long-range circuitry, APOE ɛ4 allele-related alterations in functional communication between hemispheres have rarely been directly investigated. We examined the alteration of resting-state functional connectivity (RSFC) between inter-hemispheric homotopic regions in cognitively intact, elderly APOE ɛ4 carriers. The voxel-mirrored homotopic connectivity method was used to assess the inter-hemispheric RSFC. The current study included 13 cognitively intact, elderly APOE ɛ4 carriers (with at least one copy of APOE ɛ4 allele) and 22 well-matched ɛ3 homozygotes. Comparisons between the two groups were conducted, and subsequently, the correlation between the differential inter-hemispheric RSFC and cognitive ability was analyzed. Compared with ɛ3 homozygotes, APOE ɛ4 carriers showed decreased inter-hemispheric RSFC in the bilateral medial temporal lobe (MTL) and orbital frontal cortex (OFC). Moreover, in APOE ɛ4 carriers, the inter-hemispheric RSFC of the MTL correlated with the Wechsler Memory Scale-Logical Memory (WMS-LM) (immediate and delayed performance, r = 0.64, p < 0.05; r = 0.65, p < 0.05, respectively), and the inter-hemispheric RSFC of the OFC correlated with the WMS-LM delayed performance (r = 0.71, p < 0.05). In our study, the presence of the APOE ɛ4 allele was linked with decreased inter-hemispheric RSFC, which was attributed to memory performance in carriers.
Keywords: Alzheimer’s disease, apolipoprotein E, corpus callosum, functional magnetic resonance imaging, memory
