Estrogen Boosts Brain Power

by Women's Brain Health Initiative:Women's brains are different than men's, and that variation makes a difference. The disparity in our brains result from dissimilarity in our genes and hormones. Brains are shaped during development, just as genitalia are.Brains are also shaped by life, with culture and learning experiences changing our brains over time. One of the biggest differences between men's and women's brains is related to hormones. Hormones have been shown to affect the brain across the life span, affecting reproduction, emotion and cognition. Effects of Ovulatory CycleWomen have unique brain connections that allow them to have an ovulatory cycle during their reproductive years. Some of the effects of the ovulatory cycle include:

• Drugs are more or less effective depending on where a woman is in her ovulatory cycle.
• Pain may be less intense during the follicular phase of the menstrual cycle, when estrogen levels are highest.
• Sleep may vary subtly for some women throughout the ovulatory cycle.

Menopause and Ovary Removal Decrease EstrogenA woman's hormones vary throughout her ovulatory cycle but also vary significantly across her life span, with the biggest change occurring midlife when her reproductive years come to an end. Menopause leads to a decrease in 17-beta estradiol, a form of estrogen produced by the ovaries. With this reduction in 17-beta estradiol, women may begin to experience memory changes which ultimately may predispose them to Alzheimer's disease. Given the potential for negative cognitive impacts after menopause, researchers were curious about what happens when the ovaries are removed surgically before menopause, thereby removing a woman's major source of estrogen at an early age. Gillian Einstein, a psychology professor and cognitive neuroscientist at the University of Toronto, and her colleagues have focused their research on women who have had their ovaries removed before natural menopause and do not go on hormone replacement therapy (HRT). By studying the women who do not have ovaries and are not having their estrogen replaced with a drug intervention, they are able to observe the impact of premature reductions in 17-beta estradiol. "Early results suggest that memory is negatively affected by estrogen deprivation," explains Einstein, "and the effects are almost immediate, and get worse over time. What this suggests is that estrogen is really important, especially for young women's brain health."Removing Ovaries Affects Entire BodyEinstein wants women to be aware of what can happen after ovary removal. While women will certainly decrease their risk of ovarian cancer, they may experience cognitive changes and negative impacts on their bone and heart health, as well as their immune system. "It is important to recognize that removing ovaries does not just affect the reproductive system but the entire body," she says. "Unless a woman actually has ovarian cancer, it would be best if she could keep her ovaries," urges Einstein. Of course, there are some very good reasons for a woman to undergo the removal of her ovaries; it's not always possible to avoid removal of your ovaries. For those women who do end up having their ovaries removed, Einstein advises, " Estrogen replacement therapy may be extremely important but it’s a complex topic. It may be contra-indicated, as in the case of women with breast cancer, but in some cases it appears to be an extremely beneficial treatment option.So it's critical for doctors to consider each woman's unique circumstances when deciding whether or not to prescribe HRT, which type of therapy to use, and the dosage. Estrogen is a very powerful molecule and more research is needed to better understand how it can be used most effectively as a treatment.”Why Aren't Women Studied More? If there are these differences between men's and women's brains, and these differences have an impact on health and determining appropriate treatments, why aren't women being studied more? Einstein believes there are a number of possible explanations. There may be social reasons, i.e. it seems politically incorrect to differentiate between the sexes.There may be a reluctance to look for these differences because we don't know what to do with the results. Probably the most significant reason is economic. It is more complex and thus costs more money to consider sex differences in research studies; more participants are needed, more analysis is required, and the study design must take into account the variations caused by female participants' menstrual cycle.Just because the research is more complex doesn't mean it should be avoided. "Justice demands that we study women's brains - we're half the population," says Einstein with determination. "It's good science. It will lead to better medicine and innovation. We'll learn new things about the brain that we didn't know before and that will have a positive impact on everyone, men and women."