Background: Apolipoprotein E (APOE) epsilon4 is the only established risk gene for late-onset, sporadic Alzheimer's disease (AD). Previous studies have provided inconsistent evidence for the effect of APOE epsilon4 status on the visuospatial working memory (VSWM). Objective: The aim was to investigate the effect of APOE epsilon4 on VSWM with an event-related potential (ERP) study in healthy controls (HC) and amnestic mild cognitive impairment (aMCI) patients. Methods: The study recorded 39 aMCI patients (27 APOE epsilon4 non-carriers and 12 APOE epsilon4 carriers) and their 43 matched controls (25 APOE epsilon4 non-carriers and 18 APOE epsilon4 carriers) with an 64-channel electroencephalogram. Participants performed an N-back task, a VSWM paradigm that manipulated the number of items to be stored in memory. Results: The present study detected reduced accuracy and delayed mean correct response time (RT) in aMCI patients compared to HC. P300, a positive component that peaks between 300 and 500 ms, was elicited by the VSWM task. In addition, aMCI patients showed decreased P300 amplitude at the central-parietal (CP1, CPz, and CP2) and parietal (P1, Pz, and P2) electrodes in 0- and 1-back task compared to HC. In both HC and aMCI patients, APOE epsilon4 carriers showed reduced P300 amplitude with respect to non-carriers, whereas no significant differences in accuracy or RT were detected between APOE epsilon4 carriers and non-carriers. Additionally, standardized low-resolution brain electromagnetic tomography analysis (s-LORETA) showed enhanced brain activation in the right parahippocampal gyrus (PHG) during P300 time range in APOE epsilon4 carriers with respect to non-carriers in aMCI patients. Conclusion: It demonstrated that P300 amplitude could predict VSWM deficits in aMCI patients and contribute to early detection of VSWM deficits in APOE epsilon4 carriers.
Gao, L., Chen, J., Gu, L., Shu, H., Wang, Z., Liu, D., … Zhang, Z. (2018). Effects of gender and apolipoprotein E on novelty MMN and P3a in healthy elderly and amnestic mild cognitive Impairment. Frontiers in Aging Neuroscience, 10(AUG). https://doi.org/10.3389/fnagi.2018.00256