APOE and Alzheimer disease: On the other hand, in some studies, parous women had greater cognitive decline on Mini-Mental State Examination (MMSE) scores (McLay et al., 2003), higher AD risk (Colucci et al., 2006) and a younger age at AD onset as compared to nulliparous women (Ptok et al., 2002), effects that seemed, however, limited to APOE-4 non-carriers (Corbo et al., 2007).