Over the past century, the average lifespan of women has increased from 50 to over 80 years, but the age of the menopause has remained fixed at 51 years. This "change of life" is marked by a dramatic and permanent decrease in circulating levels of ovarian estrogens. Therefore, more women will live a greater proportion of their lives in a chronic hypoestrogenic state. Ovarian steroid hormones are pleiotropic and have multiple, diverse, and possibly opposing actions in different contexts. In light of recent reports of the possible health risks of hormone replacement therapy (HRT) on several different physiological systems, the question of whether estrogens are protective or risk factors must be carefully re-evaluated.

中文翻译：

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雌激素：脑功能的保护或危险因素？

在过去的一个世纪中，妇女的平均寿命从50岁增加到80岁以上，但绝经年龄一直固定在51岁。这种“改变生活”的特征是卵巢雌激素循环水平显着和永久性降低。因此，更多的妇女将在慢性雌激素低下的状态下生活。卵巢类固醇激素具有多效性，在不同情况下具有多种，多种多样且可能相反的作用。根据最近的报道，激素替代疗法（HRT）在几种不同的生理系统上可能对健康造成的风险，必须仔细重新评估雌激素是保护性还是危险因素的问题。