Is timing everything? New insights into why the effect of estrogen therapy on memory might be age dependent.
Is timing everything? New insights into why the effect of estrogen therapy on memory might be age dependent.
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DOI：
10.1210/en.2013-1598
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发表时间：
2013-09
期刊：
影响因子：
4.8
通讯作者：
P. Maki
中科院分区：
文献类型：
--
作者：
P. Maki
Despite controversy concerning relative risks and benefits, hormone therapy (HT) remains the most effective treatment for vasomotor symptoms associated with menopause (1). Understanding the factors that determine the health outcomes associated with HT is therefore a key priority. One critical factor is the age at which treatment is initiated. Perhaps the most compelling evidence in support of that view comes from the very study that raised concerns about the risks of HT, the Women's Health Initiative (WHI). After an average of 7.1 years of follow-up, the WHI Estrogen-Alone Trial was stopped early because of an increased risk of stroke that was equivalent to an absolute excess risk of 12 additional strokes per 10 000 person years (2). After a mean of 10.7 years of follow-up in that trial, the impact of conjugated equine estrogens (CEE) on health outcomes, including coronary heart disease, myocardial infarction, colorectal cancer, total mortality, and a global index of chronic disease, was more favorable for women aged 50–59 at treatment initiation compared with women who initiated treatment at older ages (3). Within the 50- to 59-year-old group, the risk of coronary heart disease and total myocardial infarction was significantly reduced with CEE (3). (The risk of stroke was no longer elevated during the postintervention follow-up period). Thus early age at initiation was a critical determinant of the long-term impact of estrogen treatment. Such data support the hypothesis that estrogen treatment may confer benefits when initiated early, a hypothesis that is referred to in the literature as the “timing hypothesis,” the “window of opportunity hypothesis,” or the “critical window hypothesis.”
