The Female Brain
As a medical student, Louann Brizendine was aware of the conclusive studies done around the world which showed that women suffer from depression at a ratio of 2:1 compared to men. Going through college at the peak of the feminist movement, along with many others she believed this was the result of ‘the patriarchal oppression of women’. But it came to her notice that, up until puberty, depression rates between boys and girls are the same. Could the hormonal changes to girls in the early teenage years might make them suddenly more prone to getting depressed? Later, as a psychiatrist, she worked with women suffering from the extremes of pre-menstrual syndrome, and was struck by the extent to which the female brain is shaped by dramatic changes in hormonal chemistry, driving a woman’s behavior and creating her reality.
In 1994, Brizendine established the Women’s Mood and Hormone Clinic in San Francisco, one of the first of its type in the world. The Female Brain, the culmination of the author’s 20 years practice as a neuropsychiatrist, pulls together her own research and the latest findings from a range of disciplines. Contrasting the relative stability of male hormonal brain states compared to the female, which involve an often complex cocktail of chemicals and change dramatically from girlhood to adolescence, early adulthood, motherhood and menopause, the book brilliantly shows why woman’s brain states and chemistry merit independent research, and why generalities about ‘human behavior’ usually relate to male behavior.
Brizendine includes fascinating chapters on the female brain in love, the neurobiology of sex, the ‘mommy brain’ (how a woman’s thinking changes according to altered brain chemistry in pregnancy) and the mature female brain, post-menopause. We focus on here on some of her insights regarding the infant and pubescent female brain.
Basic sex differences
Even taking into account differences in body size, Brizendine notes, the male brain is about nine per cent larger than the female. This fact was once interpreted as meaning that women were not as smart as men. In fact, women and men have the same number of brain cells, but the woman’s is more tightly packed into the skull.
In the areas of the brain dealing with language and hearing, women have a full 11% more neurons than men, and the part of the brain associated with memory, the hippocampus, is also larger in women. The circuitry for observing emotion on other peoples’ faces is again larger compared to the male. In relation to speech, emotional intelligence and the ability to store rich memory, therefore, women have a natural advantage.
Men, on the other hand, have more processors in the amygdala, a part of the brain which regulates fear and aggression. This perhaps explains why males are more likely to anger quickly and take violent action in response to immediate physical danger. Women’s brains also evolved to deal with possibly life-threatening situations, but in a different way. The female brain experiences greater stress over the same event as a man’s, and this stress is a way of taking account of all possible risks to her children or family unit. This is why, Brizendine suggests, a modern women can view some unpaid bills as catastrophic, as it will seem a threat to the family’s very survival.
The field of brain sex differences has received a huge boost through brain scanning and imaging technologies which actually allow us to see the workings of the brain in real time. The lights up in different places depending on whether we are in love, looking at faces, solving a problem, speaking or experiencing anxiety, and these hot spots differ between men and women’s brains. Women actually use different parts of the brain and different circuits than men to accomplish the same tasks, including solving problems, processing language, and generally experiencing the world.
One other basic brain difference is noteworthy. Studies have shown that men think about sex on average every 52 seconds, while for women it is once a day. As the parts of the brain where sexual thought and behavior is generated is two and a half times larger in the male, this is not surprising.
The baby female brain
Until they are eight weeks old, the brains of male and female foetuses look the same – ‘female is nature’s default setting’, Brizendine observes. At about eight weeks, a male foetus’s brain is flooded with testosterone, which kills off the cells relating to communication and helps to grow cells relating to sex and aggression. Biochemically, the male brain is now significantly different from a female one, and by the time the first half of the pregnancy is over, the differences between male and female brains are mostly set.
A female baby comes into the world wired to notice faces and hear vocal tones better. In the first three months of her life a baby girl’s abilities at ‘mutual gazing’ and eye contact grow 400 per cent. In the same period, these abilities do not grow at all in boys.
It is well-known that girls usually begin speaking sometime before boys, thanks to the more well-developed language circuitry of the their brains. This continues into adulthood, with women speaking on average 20,000 words a day and men averaging only around 7,000. (As Brizendine remarks, this higher ability ‘wasn’t always appreciated’, with some cultures locking up a woman or putting a clamp on her tongue to stop the chatter.)
One other important difference in infancy is that baby girls are more sensitive to the state of their mother’s nervous systems. It is important that infant girls do not have mothers who are stressed out, as when the girl grows up to have children of her own her ability to be nurturing will be reduced. However, armed with this knowledge, it is possible to break the cycle of mother-infant stress.
The teen girl’s brain
At puberty, a girl’s thinking and behavior changes according to the fluctuating levels of oestrogen (one of the ‘feel good’ hormones), progesterone (‘the brain’s valium’) and cortisol (the stress hormone) in her brain. Other important hormones produced are oxytocin (which makes us want to bond, love and connect with others) and dopamine (stimulates the brain’s pleasure centers).
The effect of these chemicals is to give a teenage girl a great need for, and pleasure in, gossiping, shopping, exchanging secrets, experimenting with clothing and hair styles – anything that involves connecting and communicating. Teenage girls are always on the phone because they actually need to communicate to reduce their stress levels. Their squeals of delight at seeing friends, and the corresponding panic at being grounded, is also a part of these changes. The dopamine and oxytocin rush girls experience is “the biggest, fattest neurological reward you can get outside of an orgasm”, Brizendine remarks.
Why exactly does the loss of a friendship feel so catastrophic to a teenage girl, and why is her group so important to her? Physiologically, she is reaching the optimum age for child-rearing, and in evolutionary terms she knows that a close-knit group is good protection, since if she has a small child with her she is not able to attack or run away as a man can. (Cannon’s 1932 concept of ‘flight or flight’ in response to danger is an observation of men rather than women.) As the threat of losing close ties to a group can be frightening, female friendships need to be tight. Close social bonds actually alter the female brain in a highly positive way, such that any loss of those relationships triggers a hormonal change which intensifies the feelings of abandonment or loss. The intensity of female pubescent friendships therefore also has a biochemical basis.
The teenage girl’s confidence and ability to deal with stress change according to the time of the month, and Brizendine has treated many ‘problem’ girls who experience higher than average hormonal changes. The most brash and aggressive girls often have high levels of androgens, the hormones associated with aggression. At normal levels, fluctuations in androgens can cause a girl to be more focused on power, whether within the peer group or over boys.
Incidentally, why do boys often become brooding and monosyllabic? The testosterone that marinates their brains not only drives them to ‘compelling masturbatory frenzies’, but also reduces their wish to talk or socialize if it does not involve girls or sport.
In summary, in the teen years the differing hormonal affects on the brain cause males and females to go off in different directions: boys gain self-esteem through independence from others, while females gain it through the closeness of their social bonds.
Brizendine began her career in psychiatric work and later moved to neurology. This unusual perspective has made her less willing to speculate on psychological or sociological ideas that have little to with how the brain actually works; though clearly a feminist, she warns that political correctness has no role in understanding behavior. Yes, we may be able to alter our cultural attitudes or policies to make a better world, but first we must understand the facts about how brain biology – so different between men and women* - shapes behavior.
Yet Brizendine says that “Biology powerfully affects, but does not lock in our reality.” That is, if we know about the physiological or genetic forces that shape us, we will be able to take account of them. The availability of estrogen in pill form and the fact that we can replace hormones (the author includes a long appendix on hormone replacement therapy) means that women can now control their day experience of reality, and perhaps such treatments will end up having as great an impact on women’s lives and destinies as the contraceptive pill.
Subtracting the copious appendices and notes, The Female Brain is only 200 pages long. As an enjoyable and often witty popular synthesis of the latest research on the subject, it is likely to be read for many years to come, in the same way that Anne Moir and David Jessel’s Brainsex: The Real Difference Between Men and Women provided an epiphany for many a reader on the biology of gender difference. With many additional insights into the male brain, this is a book for everyone.
* Brizendine weighs into the debate sparked by Harvard University president Lawrence Summers, who said in a 2005 speech that the differences in achievement between men and women in mathematics and the sciences was due to natural brain differences between the sexes. Brizendine notes that until puberty, boys and girls are exactly the same in mathematical or scientific achievement. However the testosterone that floods the male brain makes boys extremely competitive but also more willing to spend many hours studying alone or working on their computers. With the teenage girl’s flood of oestrogen, in contrast, she becomes a lot more interested in social bonding and her emotional life, and as a consequence is unlikely to sit for hours alone pondering mathematical puzzles or battling to top the class. Even as adults women are compelled by their brain chemistry to want to communicate and connect, and this favours them less for the sort of solitary work often required by mathematical, scientific or engineering careers. Brizendine’s theory in a nutshell: It is not lack of aptitude that makes women stay out of these fields, but brain-driven attitudes to the work involved.
Source: Tom Butler-Bowdon Psychology Classics: Who We Are, How We Think, What We Do. Insight and inspiration from 50 key books (Nicholas Brealey, London & Boston).
Brizendine’s first degree was in neurobiology from the University of California, Berkeley (1972-76), followed by medicine at Yale University, and psychiatry at Harvard Medical School (1982-85). After a stint teaching at Harvard, in 1988 she accepted a post at the Langley Porter Psychiatric Institute at University of California, San Francisco, where in 1994 her Women’s Mood and Hormone Clinic was established.
She continues to combine research work with clinical practice and teaching, focusing on the affects on mood, energy, sexual function and general well-being of hormonal influences on the brain. Her book The Male Brain was published in 2010.