APOE and Cognitive impairment: Even though a number of risk factors for sporadic Alzheimer’s disease (AD), the most common type of dementia, have been discussed (e.g., diagnosis of mild cognitive impairment (MCI), hippocampal atrophy, family history of AD, apolipoprotein-E ε4 allele [APOE-ε4]), one of the most well-documented risk factors for the disease is increasing age (Ferreira et al., 2014; Naj et al., 2014).