The Female Brain (25 page)

My intentions for this book were to help women through the various shifts in their lives: shifts so big they actually create changes in a woman’s perception of reality, her values, and what she pays attention to. If we can understand how our lives are shaped by our brain chemistry, then maybe we can better see the road ahead. It’s important to visualize and plan for what’s coming. I hope this book has made a contribution to the mapping of the female reality.

There are those who wish there were no differences between men and women. In the 1970s at the University of California, Berkeley, the buzzword among young women was “mandatory unisex,” which meant that it was politically incorrect even to mention sex difference. There are still those who believe that for women to become equal, unisex must be the norm. The biological reality, however, is that there is no unisex brain. The fear of discrimination based on difference runs deep, and for many years assumptions about sex differences went scientifically unexamined for fear that women wouldn’t be able to claim equality with men. But pretending that women and men are the same, while doing a disservice to both men and women, ultimately hurts women. Perpetuating the myth of the male norm means ignoring women’s real, biological differences in severity, susceptibility, and treatment of disease. It also ignores the different ways that they process thoughts and therefore perceive what is important.

Assuming the male norm also means undervaluing the powerful, sex-specific strengths and talents of the female brain. Until now, women have had to do most of the cultural and linguistic accommodating in the work world. We have been fighting to adapt to a man’s world—after all, women’s brains are wired to be good at changing. I hope this book has been a guide—for us, our husbands, fathers, sons, male colleagues, and friends—to the minds and biobehavior of women. Perhaps this information will help men begin adapting to our world.

Almost every woman I have seen in my office, when asked what would be her top three wishes if her fairy godmother could wave her magic wand and grant them, says, “Joy in my life, a fulfilling relationship, and less stress with more personal time.” Our modern life—the double shift of career and primary responsibility for the household and family—has made these goals particularly difficult to achieve. We are stressed out by this arrangement, and our leading cause of depression and anxiety is stress. One of the great mysteries of our lives is why we as women are so devoted to this current social contract, which often operates against the natural wiring of our female brains and biological reality.

During the 1990s and the early part of this millennium, a new set of scientific facts and ideas about the female brain has been unfolding. These biological truths have become a powerful stimulus for the reconsideration of a woman’s social contract. In writing this book I have struggled with two voices in my head—one is the scientific truth, the other is political correctness. I have chosen to emphasize scientific truth over political correctness even though scientific truths may not always be welcome.

I have met thousands of women during the years my clinic has been running. They have talked to me about the most intimate details of events in their childhoods, teen years, career decisions, choice of a mate, sex, motherhood, and menopause. While female brain wiring has not changed much in a million years, the modern challenges of the different phases of women’s lives are remarkably different from those of our foremothers.

Even though there are now proven scientific differences between men’s and women’s brains, this, in many ways, is the Periclean golden age for women. The age of Aristotle, Socrates, and Plato was the first time in Western history that men gained enough resources to have the leisure for intellectual and scientific pursuits. The twenty-first century is the first time in history that women are in a similar position. We have not only the critical, unprecedented control over our fertility but independent economic means in a networked economy. Scientific advances in women’s fertility have given us enormous options. We can now choose when, if, and how to bear children over many more years of our lives. We are no longer economically dependent on men, and technology has provided the flexibility to toggle between professional and domestic duties at the same time and in the same place. These options give women the gift of using their female brains to create a new paradigm for the way they manage their professional, reproductive, and personal lives.

We are living in the midst of a revolution in consciousness about women’s biological reality that will transform human society. I cannot predict the exact nature of the change, but I suspect it will be a shift from simplistic to deep thinking about the changes we need to make on a grand scale. If external reality is the sum total of the way people conceive it, then our external reality will change only when the dominant view of it changes. The scientific facts behind how the female brain functions, perceives reality, responds to emotions, reads emotions in others, and nurtures and cares for others are women’s reality. Their needs for functioning at their full potential and using the innate talents of the female brain are becoming clear scientifically. Women have a biological imperative for insisting that a new social contract take them and their needs into account. Our future, and our children’s future, depends on it.

APPENDIX ONE

The Female Brain
and Hormone Therapy

I
N
2002
THE
Women’s Health Initiative (WHI) and Women’s Health Initiative Memory Studies (WHIMS) found that women who took a specific type of hormone therapy for six years, starting at age sixty-four or older, had a small increase in the risk of breast cancer, stroke, and dementia. Ever since, hormone therapy (HT) for women has been downright confusing. Doctors have been massively backpedaling on what they had told their women patients about hormone therapy. And both the doctors and the women caught in the middle have felt betrayed.

The big question remains: whether or not to take hormones during or after menopause. Women want to know, Will the benefits outweigh the risks for me personally? Since the average woman in the WHI study was sixty-four years old and hadn’t been on any hormones for thirteen years after menopause, do the study results pertain to, say, a fifty-one-year-old woman now going through menopause and feeling miserable? Or a sixty-something woman who has been on and off hormone therapy? Women ask, Will my brain be able to adjust to no estrogen? Will my brain cells be unprotected if I don’t take hormone therapy?

Since the WHI study was not designed to answer questions about hormone therapy and protection of the female brain, we must turn to other studies that have looked directly at the effects of estrogen on the brain.

Estrogen’s effect on brain cells and function has been extensively studied in female laboratory rodents and primates. These studies have clearly shown that estrogen promotes brain cell survival, growth, and regeneration. Other studies in women suggest many benefits of estrogen on the growth of neurons and maintenance of brain function as we age. These studies scanned the brains of postmenopausal women, some who took HT and others who did not. The following areas were spared the usual age-related shrinkage in women taking HT: the prefrontal cortex (an area for decision making and judgment), the parietal cortex (an area for verbal processing and listening skills), and the temporal lobe (an area for some emotional processing). Given these positive studies, many scientists now believe that HT should be thought of as a protector against age-related brain decline, although this belief conflicts with the findings of WHI and WHIMS.

It’s important to note that there has been no long-term study of the brain effects of estrogen therapy in women who start taking hormones right at menopause, around age fifty-one. The Kronos Early Estrogen Prevention Study, begun in 2005, was designed by Fred Naftolin and colleagues at Yale to research the effects of giving HT to women ages forty-two to fifty-eight, right at the perimenopause and menopause. Its results are due sometime after 2010. Until then, what information other than WHI and WHIMS can we rely on to make our decisions?

On the positive side, the Baltimore Longitudinal Study of Aging—the longest-running scientific study of human aging in the United States, begun in 1958—found numerous brain benefits from HT. Women on hormone therapy, the study shows, have greater relative blood flow in the hippocampus and other brain areas related to verbal memory. They also perform better on verbal and visual memory tests than women who had never been treated with HT. Hormone therapy—with and without progesterone—also helps protect the structural integrity of brain tissue, preventing the usual shrinkage seen with age.

Certain brain regions age faster or more slowly in males and females, just as they develop at different rates early in life. We know that men’s brains shrink faster with age than women’s brains. This is especially true in regions such as the hippocampus; the prefrontal white matter, which speeds decision making; and the fusiform gyrus, an area involved in facial recognition. Researchers at UCLA found that postmenopausal women on estrogen therapy were less depressed and angry and performed better on tests of verbal fluency, hearing, and working memory than did postmenopausal women who were not taking estrogen, and they outperformed men, too. By contrast, researchers at the University of Illinois found that women who had never taken HT had significantly more shrinkage in all brain areas than did women who took HT. They also found that the longer women took HT, the more gray matter, or brain cell volume, they had compared with women who weren’t taking HT. These positive effects held and even increased the longer a woman took HT.

Each woman, of course, is an individual, and her brain is quite different not only from a man’s but from other women’s. This variation makes brain comparison studies between individuals difficult. One way around this difficulty, is to examine identical twins. A Swedish study looked at pairs of postmenopausal female twins, from age sixty-five to eighty-four, in which one twin took HT while the other did not over many years. The HT users had better scores on tests of verbal fluency and working memory than their twin sisters. The twins on HT, in fact, showed 40 percent less cognitive impairment, regardless of the type and timing of the hormone treatment.

Barbara Sherwin in Canada has also been studying the effects of estrogen on the brains of postmenopausal and posthysterectomy women for over twenty-five years. In her research, estrogen treatment showed protective effects on verbal memory in healthy, forty-five-year-old, surgically menopausal women who had been given estrogen immediately after their operations. However, no effect was found when estrogen was given to older women years after their surgical menopause. These findings suggest that there is a critical time for initiating estrogen therapy following menopause. Sherwin believes these factors may explain why no protective effect of HT on cognitive aging was found in the WHIMS.

These recent studies on the brain-preserving effects of HT, and the contradictory results of the WHI and WHIMS, highlight some of the current controversies surrounding postmenopausal hormone therapy and the female brain.

F
REQUENTLY
A
SKED
Q
UESTIONS

What happens to my brain as I pass through menopause?

Menopause itself technically lasts for only twenty-four hours—the day that is twelve months after your final period. The very next day you begin the postmenopause. The twelve months leading up to that single day of menopause make up the last months of the so-called perimenopause. At age forty to forty-five, the female brain begins the early phase of perimenopause, the two to nine years before the day of menopause. At this stage, the brain for some reason starts to become less sensitive to estrogen. The precisely timed dialogue between the ovaries and brain begins to get garbled. The biological clock controlling the menstrual cycle is wearing out. This difference in sensitivity causes the timing of the menstrual cycle to change, and periods start to come a day or two earlier. It can also cause menstrual blood flow to change. As the brain becomes less sensitive to estrogen, the ovaries may try to compensate some months by making even more estrogen, causing heavier menstrual flow. This decrease in sensitivity to estrogen in the brain can also trigger a cascade of symptoms that vary from month to month and year to year, ranging from hot flashes and joint pain to anxiety, depression, and changing levels of libido.

Depression is a surprisingly common problem in perimenopause. Researchers at the National Institute of Mental Health found that perimenopausal women have fourteen times the normal risk of depression. That risk is especially high during late perimenopause, the two years before menstruation stops. Why might this be so? At the maximum period of estrogen change, the neurochemicals and brain cells that are usually supported by estrogen—such as serotonin cells—have become disturbed. This perimenopausal depression can sometimes be treated with estrogen therapy alone if it is mild. Bottom line, the transition through perimenopause can be a time of vulnerability to mood instability and irritability because of the brain’s changes in estrogen and stress sensitivity. Depression can come out of the blue, even for women who’ve never previously experienced it.