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This article, written by Glen Pyle, of the University of Guelph, was originally published in The Conversation and is republished here with permission:
Hormone replacement therapy in postmenopausal women was once considered a fountain of youth. Studies have shown that regular supplementation with estrogen decreases the risk of cardiovascular disease, the leading cause of death in women.
This idea collapsed in 2002 when the Women's Health Initiative trial in the United States revealed an increased risk of coronary artery disease, invasive bad cancer, stroke, and pulmonary embolism in women receiving bad cancer. combined hormonal replacement therapy estroprogestative. The trial was stopped early because the health risks were greater than the health benefits.
However, a new study from our laboratory at the University of Guelph suggests that it may only be a matter of time before the return of estrogen therapy.
Estrogens as heart protectors
Before menopause, death rates from cardiovascular disease were lower in women than in men of the same age. After menopause, the risk for women increases to reach or even exceed that of men of the same age. The link between increased estrogen levels in younger women and the low risk of cardiovascular mortality is known as the "estrogen protection hypothesis."
In the 1960s, estrogen was a popular treatment to help women stay "feminine forever" – an unfortunate phrase and concept that divided feminist health activists.
Initially, estrogens were approved to treat osteoporosis, but the benefits went beyond the protection of the bones. An early meta-badysis suggested that estrogen supplementation added one or more years to the life expectancy of women, mainly by reducing mortality from cardiovascular disease.
Increased risk of bad cancer
The Women's Health Initiative was at the time the largest clinical trial on the benefits of estrogen therapy. The study included more than 25,000 women who received various types of hormonal treatments. In 2002, the results were published and showed an increased risk of bad cancer and coronary artery disease.
Although the lack of benefits of estrogen therapy is evident, it has not been clear how such a promising treatment could fail so dramatically.
Although the first results of the Women's Health Initiative were discouraging, another badysis published in 2007 showed that women who started treatment less than 10 years after menopause had cardiovascular benefits, unlike those who delayed the start of treatment. This idea is known as the "temporal hypothesis".
Many hormone replacement therapy trials have used different formulations of hormones as treatments and have distributed them to patients in different ways. What types of hormones have been used, whether women take them in pill form or timbre – and the timing of these treatments – could have a significant impact on the results.
Perimenopause changes cardiac response
Most basic research on menopause uses animals whose ovaries are removed surgically. This is a reasonable model for women who become menopausal with the removal of the ovaries, but it does not account for the gradual transition from perimenopause to most women.
Our research focused on cardiac changes during the transition to menopause using a unique mouse model developed by Dr. Patricia Hoyer's group at the University of Arizona.
During perimenopause, the heart seems to be functioning normally. But at the molecular level, it's another story. Stress molecules, called cytokines, increase during perimenopause and the heart muscle is more dependent on calcium to stimulate contraction. Over time, cytokines and an increase in calcium damage the heart. Our study is the first to show that the heart is negatively affected even before the end of menopause.
Estrogen replacement therapy is based on the idea that the reintroduction of estrogen after menopause replenishes the benefits seen in younger women. In our study, we found that perimenopause alters the heart's response to estrogen.
In short, the heart treated after menopause is profoundly different from the heart before menopause.
The timing of the treatment maximizes the benefits
Clinical trials show that estrogen therapy started early after menopause, which maximizes its benefits. Our work showed that the heart was reshaping even before the end of menopause, bringing the therapeutic window earlier than expected.
This transformation helps to explain why the timing of estrogen treatment is so important and demonstrates that the heart is affected very early in the transition to menopause.
This means that estrogen replacement therapy is most likely to reduce the risk of cardiovascular disease if it is started shortly after menopause, or even during perimenopause.
Is it time to re-examine the use of estrogen as a post-menopausal treatment to reduce the number of deaths from cardiovascular disease? More research is needed before this step, but it is clear that time is running out.
Glen Pyle, professor at the University of Guelph
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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