The Female Brain (27 page)

Unfortunately, estrogen loss isn’t the only brain drain for females around menopause. By age fifty, many women have lost up to 70 percent of their testosterone. This is because not only do the ovaries stop manufacturing as much at menopause but the adrenal glands, which provide 70 percent of a woman’s androgens and testosterone, made as a prehormone called DHEA, during her fertile years, have greatly decreased their production, too, resulting in a hormone transition called “adrenopause.” After menopause, the adrenal glands—even with their diminished production—supply over 90 percent of a woman’s androgens and testosterone. Both men and women, in fact, go through this testosterone and androgen loss from the adrenal gland, as some of the adrenal cells die starting at about age forty. By age fifty, men have lost half of their adrenal testosterone and 60 percent of the testosterone produced by the testes when they were young. Men’s sex drive, as a result, often declines in these years. Since testosterone is required to stimulate sexual interest in the brain, the plunge in testosterone after menopause can cause women to feel little or no interest in sex.

Males, for most of their adulthood, produce ten to one hundred times as much testosterone as females do. Their testosterone levels range from 300 to 1000 (picograms per milliliter), compared with 20 to 70 for women. Even though men’s testosterone drops 3 percent a year on average from its high, at age twenty-five, it usually stays well above 350 into middle age and beyond—and 300 picograms per milliliter is all men need to maintain sexual interest. It takes much less testosterone to spark sexual urges in a woman, but she does need enough to trigger her brain’s sex center. Women’s youthful testosterone high is at age nineteen, and by the age of forty-five or fifty, women’s levels have dropped by up to 70 percent—leaving many with very low testosterone levels. In these cases, like a car that’s out of gas, the sex center in the hypothalamus doesn’t have the chemical fuel it needs to ignite sexual desire and genital sensitivity. The physical and mental engines of sexual arousal stall.

Complaints about women’s sexual interest and performance are extremely common at all ages. Four in ten American women—nearly half—are unhappy with some aspects of their sexual lives, and between the ages of forty and fifty, that number climbs to six in ten. Some of the most widespread complaints in women during and after the perimenopause are diminished sex interest and arousal, difficulty achieving orgasms, weaker orgasms, and aversion to physical or sexual touch. Millions of women suddenly see their sex drive disappear—and researchers have found strikingly similar patterns all over the world. The biological reasons for this decline are profound hormonal changes in the brain. The estrogen, progesterone, and testosterone surges from the ovaries that formerly marinated the brain are now ending. Androgen and testosterone production by the adrenal glands and ovaries, which surged around puberty and remained high into a woman’s twenties and early thirties, dwindles by about 2 percent per year, until by the age of seventy or eighty we have only 5 percent of what we had when we were twenty. Libido in women decreases with age starting in the third decade of life and is especially prevalent if women have had their ovaries removed.

Sexual intercourse and interest in sex in women begin to decline in the fourth and fifth decades. Most women who have sexual partners at menopause continue to have sex. Studies in nursing homes have shown that a quarter of women ages seventy to ninety still masturbate. For those who have experienced declining sexual interest and want to dial it back up again, restoring testosterone to more youthful levels with gels, creams, or pills may help. Until recently, however, medical science paid scant attention to testosterone deficiency in females. Doctors feared, instead, that women might have too much of this chemical traditionally associated with masculinity and develop unnatural male traits, such as facial hair, aggression, and deep voices. In large measure because of this bias, there’s been almost no focus until recent years on the real and troubling effects for women of too little testosterone.

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Those who grew up in the culture of the feminist and sexual revolutions and beyond believe that hot, passionate, satisfyingly orgasmic sex is something to which women should feel entitled. Over the last two or three decades, the stereotype of the easily aroused, enthusiastically sexual, even predatory female has replaced the more traditional view of the demure woman who has to be seduced or loosened up with alcohol. But this new woman is a fiction in much the same way her reticent forerunner was. Unfortunately, the truth is, many women discover at the beginning of menopause that good sex is not only hard to find but also physically challenging, impossible, or unappealing. We may suddenly find ourselves grappling with low or no sex drive, arousal problems, or the inability to have an orgasm—physical changes that can be surprising and discouraging, to say the least. I see women with these issues every day in my clinic. My patients complain that it has been hard for them to find a doctor who is knowledgeable about the female sexual response—how it can vary with hormones and from person to person, and how it can change dramatically over the course of a woman’s life. To this day, most medical schools don’t teach a required course in female sexual response.

Even gynecologists, who specialize in body parts below the waist, have few answers for women with sexual problems and often find no physical reasons for their symptoms. As a result, they tend to dismiss these issues as “simply part of getting older”—ignoring the toll they can take on women’s relationships and quality of life. Psychiatrists and couples’ therapists can be equally ill-equipped to offer help. They tend to see the problem as all in the head—the result of stress in the relationship or long-term problems with intimacy. A classic response to these issues has been psychoanalysis—putting a woman on the couch for seven to ten years to get to the roots of her unnatural “frigidity” or psychological “resistance” to sex. This approach is mostly wrongheaded because the reason for these feelings at this stage of life is not a psychological conflict; it is a normal biological and psychological response to hormonal changes.

One key to restoring female libido is testosterone replacement therapy. Researchers discovered its effectiveness decades ago, but medical science in the United States has largely ignored or forgotten this information. Forty years ago, in the 1970s, doctors at the University of Chicago experimentally gave large amounts of testosterone to female patients suffering from breast cancer. Their thinking was that the hormone would lower the women’s levels of estrogen, which can promote cancer. It didn’t, but the subjects experienced a tremendous increase in their libidos and orgasmic capacity. The same effect was seen in the 1980s by Barbara Sherwin of McGill University. Sherwin replaced testosterone in women who had their ovaries removed. Those who didn’t get the hormone reported steep declines in their libidos; those who did get treatment reported that their sexual interest soon returned.

Studies are finally beginning to look at therapies for sexual dysfunction in women above the groin, targeting the female brain centers that are linked to pleasure and desire. And the treatment that does work—testosterone replacement—is finally moving into acceptance. In recent years, testosterone supplements have been a wildly popular treatment regimen for men. Only very recently, however, have doctors begun dispensing testosterone gels, patches, and creams for women patients. I’ve been prescribing testosterone replacement for women since 1994, and the results have been mostly positive.

When women complain of low libido, testosterone replacement therapy often brings their sexual interest back to par. We know that by giving testosterone we can increase a woman’s urge to masturbate and shorten her time to orgasm, but not necessarily increase her desire for partner sex. For some women, testosterone can improve sexual interest dramatically, but the hormone may not be the panacea we once thought for improving sexual interest in all women. Even men are discovering that testosterone or Viagra is not the magic bullet promised by the drug companies. However, there is no question that having a barely measurable or zero level of testosterone in men or women can be a cause of sexual dysfunction. This condition can be treated in both sexes with testosterone therapy. Women who complain of a lack of sexual interest—whether they are premenopausal or postmenopausal—deserve a trial of testosterone just as most doctors would prescribe for a man.

In addition to its effects on the brain’s sexual center, testosterone promotes mental acuity as well as muscle and bone growth. On the downside, it can contribute to thinning hair, acne, body odor, facial hair growth, and a lower voice. But the effects of testosterone on the brain—increased mental focus, better mood, more energy and sexual interest—are the reasons many men and women who take it say they are willing to assume the downside risks.

APPENDIX TWO

The Female Brain and
Postpartum Depression

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ten female brains will become depressed within the first year after giving birth. For some reason, this 10 percent of women have brains that do not entirely rebalance themselves after the massive hormone changes that follow giving birth. Postpartum psychiatric changes can range from maternity blues to psychosis, but the most common is postpartum depression. Women suffering from this condition are thought to have an increased genetic susceptibility to becoming depressed as a result of hormone changes. Ken Kendler of Virginia Commonwealth University found that there may be genes that alter the risk for depression in a woman’s response to cyclic sex hormones, particularly in the postpartum period. Such genes would affect women’s risk for major depression but would not be active in men because men lack the relevant hormonal changes. These results suggest a role for changes in estrogen and progesterone in precipitating mood symptoms among women with postpartum depression.

These 10 percent of women seem to get depressed postpartum for multiple reasons. The brain has had its stress-response “brakes” on during pregnancy; suddenly, after birth, they come off again. For 90 percent of women, the brain can return to a normal stress response, but for vulnerable women it is unable to do this. A vulnerable woman’s brain ends up hyperreactive to stress and she makes too much of the stress hormone cortisol. Her startle reflex will be up, she’ll be jumpy, small things will seem like enormous problems. She’ll be hypervigilant over the baby, hyperactive, and unable to get back to sleep after feeding the baby at night. She’ll be walking around day and night jittery, as though her finger is in a light socket even though she is exhausted.

The well-known predictors of depression after giving birth include a previous depression, depression during pregnancy, lack of proper emotional support, and high stress in the home. Women with postpartum depression were also struggling with their identities in the face of their new roles as mothers. They express feelings of loss of a sense of who they are as individuals. They feel overwhelmed by the responsibility for their child. They are coping with feeling abandoned by their partners and others close to them who aren’t supporting them enough, unreasonable worries that their child will die, and breast-feeding problems. They feel like “bad mothers,” but they never blame their child. Most mothers are reluctant to speak about their feelings and assign their moods to personal weakness rather than illness. They are struggling to keep their equality with their partners and to get the fathers involved in child care.

The transition to parenthood is often accompanied by depression and stress. It’s a whole new life and reality, so feeling rocked by the experience is understandable. In addition, mothers’ drastic hormone changes have created quantum shifts in their reality several times in less than a year. Women who are vulnerable to depression and stress may have a harder time rebalancing from these shifts. And if you’re having trouble rebalancing, a fussy child and no sleep will only increase your vulnerability to depression. For some women, these feelings of stress don’t peak until up to twelve months postpartum. Furthermore, postpartum depressive symptoms often remain hidden. Women are ashamed because they are expected to be so happy at the birth of their child. So it is important to understand the complexity of postpartum depressive mood as struggling with rebalancing brain hormones, a new identity, breast feeding, sleep, the child, and the partner.

Some scientists feel that breast feeding may be protective against postpartum depression in certain women. During lactation, mothers exhibit lower neuroendocrine and behavioral responses to several types of stressors, except possibly those representing a threat to the infant. This ability to filter relevant from irrelevant stimuli is viewed as adaptive for the mother-infant dyad, and the inability to filter stressful stimuli can be associated with the development of postpartum depression.