The impact of hormone replacement therapy on AD risk in postmenopausal women is inconsistent and may be related to APOE4 since it was reported to improve episodic memory (Burkhardt et al., 2004) and reduced the risk of cognitive impairment (Yaffe et al., 2000) albeit only in APOE-ε4 non-carriers. This evidence concerns the gene APOE and Cognitive impairment.