Why Girls Will Be Girls

Last week a routine casemeeting turned into a teachable moment for California neuropsychiatrist Louann Brizendine and her eight medical residents. Briz-endine, who works at the Langley Porter Psychiatric Institute in San Francisco, was listening to a resident run through a new patient's medical history. A successful, high-functioning working mother had come in complaining of short-term memory loss and persistent anxiety. The resident ticked off the usual details: lab tests were normal, her overall mental health was strong, no fam-ily history of early-onset Alzheimer's. The young doctors around the table looked baffled. Brizendine, who has made a reputation for pinpointing the science behind a wom-an's most complicated and bewildering feelings, immediately focused on hormones. "Is she still breast-feeding?" she asked. The resident checked her notes and nodded. "And how's her sleep? Is her husband supportive?" A typical breast-feeding woman, Brizendine explained, is awash with the hormones oxytocin and prolactin, making her more wakeful, less interested in sex and, sometimes, hyperalert. Could this explain her symptoms?

Women and hormones has long been a marital minefield and the subject of innumerable off-color jokes, but Brizendine has made it her medical specialty. For 20 years, first as a medical student at Yale, then as a faculty member at Harvard Medical School, then as director of the Women's Mood and Hormone Clinic at UCSF, she's been developing what she describes as a female-centered strain of psychiatry focusing on the complex interplay between women's mental health, hard-wiring and brain chemistry. Now her first book, "The Female Brain," which she describes as a kind of owner's manual for women, is due in bookstores next month. Brizendine realizes she's going to take some heat. "I know it's not politically correct to say this," she says, "and I've been torn for years between my politics and what science is telling us. But I believe that women actually perceive the world differently than men. If women attend to those differences, they can make better decisions about how to manage their lives."

To write the book, Brizendine melded her rich clinical experience with thousands of research studies other neuroscientists have conducted over the past 10 years. Her conclusions will seem like common sense to some and nothing short of heresy to others: she not only discusses the biological reasons girls gravitate to dolls instead of trucks but tracks the hormonal imperatives at play when a teenage female becomes obsessed with text messaging and shopping. She describes the neurological reasons why women think about sex less than men but, in their drive to produce genetically superior babies, may be having more extramarital affairs than their frustrated husbands might imagine. She also explains how changing brain chemistry can prompt a postmenopausal woman to forgo marriage counseling and dial up a divorce lawyer instead. Her ideas are certain to spark controversy from some doctors and social scientists who think books like this undercut women and reinforce old gender stereotypes. Examining the biological underpinnings of gender difference is bunk, these critics say, because there aren't many. Last year prominent psychologist Janet Hyde examined decades of studies that compared the emotional and behavioral lives of men and women and concluded that most differences between the genders were statistically "close to zero." "There is no gender-difference phenomena to explain," she says.

At first glance, Brizendine doesn't seem like the backlash type. A smallish woman with a long auburn ponytail, Brizendine, 53, talks about women's mental health with the kind of zeal she learned from her parents, who were Protestant missionaries and civil-rights activists. As an architecture student at Berkeley in the 1970s, Brizendine had a part-time job in a feminist bookstore before an internship at an immunology lab changed her life. "I realized that I loved looking at complex puzzles," she says. And nothing, she found, was more complex than the mind--especially the female variety. Her professors, though, didn't share her passion. Throughout her medical-school years at Yale, she says, no one ever mentioned women and hormones in the same breath. "When I asked about it," she says, the professors said women weren't included in mental-health studies "because their hormones would mess up the results."

By the 1990s, though, the scientific community began to recognize that, medically, women were not just small men, and started throwing research dollars into studying gender-specific medicine. Briz-endine, then a single mother with a small son, started specializing in gender-specific psychiatry, including treating women with severe PMS. "When these patients tried to talk to their own doctors or psychiatrists about how their hormones were affecting their emotions, they would get the brushoff," she says. Twelve years ago she opened her clinic, which now treats about 600 women a year with hormone-replacement therapy, psychopharmacology and cognitive behavioral therapy.

In the past six years, Brizendine says, advances in neuroimaging and neuro-endocrinology began supplying exciting new insights into how women and men use their brains differently. For example, different levels of estrogen, cortisol and dopamine, she says, can cause a female to be more stressed by emotional conflict than her male counterpart. A few unpaid bills can set off a cascade of hormones in a woman that can catapult her into a fear of impending catastrophe, a reaction triggered in men only by physical danger. Women have 11 percent more neurons in the area of the brain devoted to emotions and memory. Because they have more "mirror neurons" they are also better at observing emotions in others, she says.

All of which outrages some of Briz-endine's peers. Hyde, a psychology and women's studies professor at the University of Wisconsin-Madison, who conducted the meta-analysis of men and women last year, says she's disgusted by scientists, writers and publishers who exploit trivial differences between the genders. Books like this "are bad for my blood pressure," she says. Dr. Nancy C. Andreasen, a psychiatrist and neuroimaging expert at the University of Iowa's medical school, says nurture plays such a huge role in human behavior that focusing on biology is next to meaningless. "Whatever measurable differences exist in the brain," says Andreasen, "are used to oppress and suppress women."

Brizendine is unfazed. This fall, she's expanding her hormone and mood clinic, opening it up to teenage girls as well as women. She's thinking about writing a brain book for young girls, too. She predicts that unlike women today, the next generation--and their psychiatrists--won't assume that brain difference implies inferiority. "Doctors will help women to better manage the subtle pressures and emotional nuances in their lives," she says. And what makes them unique, she says, will help empower them, too. That's a vision of the future few women would debate.