The hypothesis that estrogen is neuroprotective for women is supported by inverse associations between indicators of lifetime EEE and late-life cognitive function[2–7], and prospective and historic cohort studies indicating adverse cognitive outcomes associated with premature surgically-induced menopause, and premature ovarian failure (POF). However, the evidence remains inconclusive. Only two studies of EEE were population-based, effects on cognition were small, and not always replicated. Although effect sizes linked to oopherectomy and POF are larger, associations with dementia were not replicated in a large Finland registry linkage study.