It’s all in your head

Susan Salter Reynolds is a Times staff writer.

IT was not until the 1990s that researchers began to study female neuroanatomy and psychology in their own right, despite growing evidence that women faced a 2-1 ratio of depression compared with men. The correlation between hormonal changes like those that trigger menstruation and increasing symptoms of depression led sociologists like Carol Gilligan to examine cultural factors, while scientists like UC San Francisco neuropsychiatrist Louann Brizendine looked at the way hormones affect brain function in various stages of a woman’s life.

In “The Female Brain,” Brizendine shares the results of two decades of research on female brain chemistry. “There are those,” she writes, “who wish there were no differences between men and women.... 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.”

Much of Brizendine’s data come from research gathered at UCSF’s Women’s Mood and Hormone Clinic, which she founded in 1994. Her book begins with a list of hormones and their effects, a list that strongly resembles the characters in a Greek tragedy: “Estrogen -- the queen: powerful, in control, all-consuming”; “Oxytocin -- fluffy, purring kitty; cuddly, nurturing, earth mother”; “Cortisol -- frizzled, frazzled, stressed out.” The author’s greatest gift to her readers is the way she takes us through the stages of a woman’s life to show the influence of hormone levels on every decision. It’s not just a matter of biology, she suggests, but also of how biology affects perception and our ability to function.


Until the age of eight weeks after birth, male and female brains are the same, Brizendine notes, as are 99% of all genetic coding. Male brains may be 9% larger, but male and female brains contain the same number of cells; female brains are more densely packed. The hippocampus (the center of emotion and memory formation) is larger in the female brain, “as is the brain circuitry for language and observing emotions in others.” The way women engage the world, as a result, is very different. Women use about 20,000 words a day, while men use 7,000. Eighty-five percent of men between the ages of 20 and 30 think about sex every 52 seconds, while women in that age group think about it, on average, once a day.

Once a child turns nine weeks, hormone types and levels begin inducing vastly different types of behavior. In female teens, this includes a propensity for drama (which increases with rising levels of estrogen and progesterone) and talking on the phone (increasing levels of oxytocin are triggered by intimacy). Predictably, Brizendine’s findings gather momentum when love and sex enter the equation. The most important challenge our early human ancestors faced, she notes, was reproduction, the passing on of genetic material and the propagation of the species.

Her take on love is distinctly unromantic: “The brain circuits that are activated when we are in love match those of the drug addict desperately craving the next fix.” Knowing what’s coming could (although it almost never does) prevent unfortunate souls from making critical decisions under the influence of love.

Chapters on “The Mommy Brain” and “The Mature Female Brain” show how changing hormone levels affect biological and emotional realities: The need for sex and the drive to care for others recede as estrogen, oxytocin and testosterone drop. This brings Brizendine to the thorny territory of hormone replacement therapy, which she discusses in an extended appendix.

For years, scientists and doctors have investigated the effects of prescribed estrogen on menopausal and post-menopausal women. Many studies indicate that it protects brain function, decreasing the moodiness and fuzziness associated with menopause. In 2002, however, the Women’s Health Initiative 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.” Brizendine believes that taking estrogen earlier, in the peri-menopausal years, decreases its dangers, and that its benefits, in the long run and in most cases, outweigh its risks.

The question that shadows “The Female Brain” is how the modern social contract (career, then love/marriage, then children) intersects with the hormonal timeline. If women spend their 20s working and begin having children in their late 30s, their 40s become a nightmare of small children and midcareer issues, all played out against peri-menopausal shifts. In light of what we now know, Brizendine reasons, this social contract should be reconsidered. “[U]nderstanding our innate biology,” she argues, “empowers us to better plan our future.”


Still, what this means in practice is vague. What gives? Job? Children? Love? Modern life is stressful, Brizendine writes, and a leading cause of depression is stress. Stress prevents women from realizing their full potential and “using the innate talents of the female brain.”

This is a lot to swallow, along with the certainty that more revelations will be coming as we continue to learn about neuroanatomy and neurochemistry. There are data, and there’s what we do with data. “I have chosen,” explains Brizendine, “to emphasize scientific truth over political correctness.” Trouble is, most scientists admit there’s no such thing as an objective observer.