Several studies reported abnormal brain activation during WM tasks were found in subjects with mild cognitive impairment (MCI) and AD [17–19] as well as in APOE-ε4 carriers [6, 14, 15, 20], which may imply the importance of WM deficit in the initial stages of the disease process and might facilitate the early detection of AD [17]. Here, APOE is linked to Alzheimer disease.