Men Responsible For Causing Menopause In Women!!

A team of scientists at McMaster University have discovered that men are responsible for menopause in women.

Rama S. Singh, a professor in McMaster's Department of Biology, along with colleagues Jonathan Stone and Richard Morton, have found that menopause is the result of natural selection.

The researchers identified that men have always had a preference for younger women when it comes to mating, which means thatolder women didn't have the need to continue to be fertile - as men avoided mating with them.

Singh, whose research specialties include the evolution of human diversity, said that "in a sense it is like aging, but it is different because it is an all-or-nothing process that has been accelerated because of preferential mating."

Experts previously believed that menopause was a way of preventing older women from reproducing, however, this new finding, published in the journal PLOS Computational Biology, suggests that it is the lack of reproduction that caused menopause.

Singh said that nobody had been able to explain why menopause is so unique to humans, only two other animals stop breeding relatively early in their lifespan - killer whales and pilot whales.

The "grandmother theory" suggests that women are unable to have children after a certain age so that they can assist with the upbringing of their grandchildren.

A study conducted at the Universities of Exeter and Cambridge, both in England, found thatfemales become increasingly genetically related to those they live with as they get older.Because of this, there is a motivation for older females to do what is best for the survival of those around them, creating a 'grandmother role'.


 However, Singh said that the theory doesn't add up:

"How do you evolve infertility? It is contrary to the whole notion of natural selection. Natural selection selects for fertility, for reproduction - not for stopping it."

This new theory says that older females had much less chance of reproducing, as men of all ages looked for younger mates.

Following this, genetic mutations occurred that brought on menopause among women when they reached a certain age, leaving them infertile.

Singh said:

"This theory says that natural selection doesn't have to do anything. If women were reproducing all along, and there were no preference against older women, women would be reproducing like men are for their whole lives."

Therefore, the development of menopause didn't occur to improve survival, it only recognized that beyond a certain age fertility didn't serve any purpose.

If the situation would have been reversed and women had historically only selected young males, men would be the one's losing fertility at a certain age, Singh pointed out.

The researchers concluded that if the theory is true, menopause could potentially be reversed one day.

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Versus women with a normal sex drive, premenopausal women who have a lack of interest in sex show distinctive blood flow patterns that activate different parts of the brain.

Researchers at Georgia Regents University recruited 16 female participants to their study. Of these, 6 had a normal sex function and a mean age of 29, while 10 of the women with a mean age of 37 had clear symptoms of "hypoactive sexual desire" - a lack of sexual desire and low sexual arousal.

The study, published in the journal Fertility and Sterility, involved measuring each woman's sexual response to explicit film clips using functional magnetic resonance imaging (MRI) - enabling the researchers to see real-time brain activation in response to a stimulus.

The women who had sexual dysfunction had a higher activation level in the area of the brain called the anterior cingulate gyrus, which triggers emotions including pain, depression and apathy.

The researchers say the brain's amygdala was also activated in the women with sexual dysfunction, a part of the brain central to processing emotion, learning and memory.

Women who had normal sexual function experienced much greater activation in the right thalamus, an area of the brain the researchers say plays a role in sexual arousal by handling sensory and motor stimuli.

The younger women without premenopausal effects on sex drive also experienced activation of the parahippocampal gyrus, the area of the brain that makes and recalls memories, the researchers say. They point out that, interestingly, this area of the brain is usually highly activated in women on hormone therapy after surgical menopause.

Dr. Michael Diamond, chairman of the department of obstetrics and gynecology at the Medical College of Georgia, explains:

"There are site-specific alterations in blood flow in the brains of individuals with hypoactive sexual disorders versus those with normal sexual function.

This tells me there is a physiologic means of assessing hypoactive sexual desire and that as we move forward with therapeutics - whether it's counseling or medications - we can look to see whether changes occur in those regions."

Dr. Diamond says that up to 20% of women may have this type of sexual dysfunction. But while there are plenty of options for men, such as the drug Viagra (sildenafil) for male impotence, there is no treatment given official approval by the US Food and Drug Administration (FDA) for women with hypoactive sexual desire.

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Today, breast cancer is one of the most feared and common type of cancer among women, statistically about 39,620 women will die from breast cancer.

The widespread rejection of estrogen therapy after the 2002 Women's Health Initiative (WHI) study has most likely led to almost 50,000 unnecessary deaths over the last 10 years among women aged 50 to 69 who have had a hysterectomy, Yale School of Medicine researchers reveal in a study published in the American Journal of Public Health.

Led by Philip Sarrel, M.D., emeritus professor in the Departments of Obstetrics, Gynecology & Reproductive Sciences, and Psychiatry, the researchers analyzed United States census data, hysterectomy rates, and estimates of decline in hormone use in women aged 50 to 59 between 2002 and 2011.

Before 2002, it was standard practice for doctors to recommend estrogen therapy for this slice of the population, and more than 90% of these women used it to treat symptoms such as hot flashes, and to prevent osteoporosis and other diseases related to menopausal hormone deficiency. Today, about 10% of these women use estrogen.

This sharp decline in estrogen usage was linked to results from one part of the large, federally funded WHI study in 2002. Women and their doctors became frightened of the dangers of post-menopausal hormones. But according to Sarrel and his colleagues, this was a report about women with a uterus, who took pills that combined estrogen and a progestin. Women who have a uterus must take a second hormone (a progestin) to avoid a risk of uterine cancer. But these results did not apply to women with no uterus who use estrogen-only therapy.

"Sadly, the media, women, and health care providers did not appreciate the difference between the two kinds of hormone therapy," Sarrel said. "As a result, the use of all forms of FDA-approved menopausal hormone therapy declined precipitously."

Sarrel added that for the women taking combined hormone therapy (at least the particular drug, Prempro, used in the WHI study), it was probably a good decision to avoid it because the WHI study showed a significant increase in breast cancer, heart disease, stroke, and blood clots in women who used this drug compared to placebo. However, for the women taking estrogen-only therapy, avoiding treatment does not appear to have been a good decision.

Results from the second part of the WHI study, which followed women who had no uterus and who took either estrogen-only or placebo, were very different. A series of papers published by the WHI between 2004 and 2012 showed that estrogen-only therapy had mostly positive health outcomes. For example, in 2011 and 2012 the WHI reported that women who received estrogen compared to those who received placebo had fewer deaths each year for 10 years and were less likely to develop breast cancer and heart disease. For each of the 10 years the death rate among those not taking estrogen was 13 more per 10,000. Most of these women died from heart disease while breast cancer accounted for almost all the other deaths.

"Estrogen avoidance has resulted in a real cost in women's lives every year for the last 10 years - and the deaths continue," said Sarrel. "We hope this article will stir an overdue debate and raise consciousness about the health benefits of estrogen-only therapy for women in their 50s with no uterus."