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Louann Brizendine devotes an entire chapter of her popular book, The Female Brain, to the teen brain. While I think Brizendine overgeneralizes from the data and relies too heavily on rat research, she makes some good points.
First, moods fluctuate wildly in adolescent girls. My favorite research on this topic was conducted by Csikszentmihalyi and Larson. They gave adolescents beepers and self-report questionnaires to record their moods and activities for a week. The subjects were beeped at random times and asked to write down what they were doing and how they felt.
It probably comes as no surprise to parents that an in-depth analysis of individual girls shows moods fluctuating rapidly from negative to positive several times each day.For further study on this topic, the reader is directed to Being Adolescent: Conflict and Growth in the Teenage Years by Mihaly Csikszentmihalyi and Reed Larson.
While it is a broad conceptual leap from behavioral observations to hormonal levels in the blood and every beginning psychology student knows correlation does not imply causation, Brizendine attributes observed mood swings to hormones. In her book, Brizendine presents a useful graph of estrogen and progesterone waves during the monthly female cycle. The graph shows that estrogen peaks prior to ovulation and then drops. And, progesterone peaks prior to menses which explains PMS.
This is where I think Brizendine should be a little more careful. By aiming her book to a popular audience, she oversimplifies things. She implies that all women go nuts around the beginning of the month. Granted this is a serious problem for a few women but Brizendine is a psychiatrist and basing her conclusions on a clinical population. Her patients are a minority. What about the rest of us that aren't seeing psychiatrists? Many, many teens and women cope very successfully with premenstrual tension and experience few problems.
Brizendine's comments dangerously echo Freud's "biology is destiny." She notices that girls are more affiliative than boys. Girls seek intimacy in their relationships and love talking with friends. We avoid conflict. We are also better readers of non-verbal communication. Boys, on the other hand, are hierarchical and seek competition.
This is not new and has been documented by developmental and social psychologists for decades. In general, boy toddlers will seek out toy trucks and girl toddlers will approach baby dolls when given a choice. These differences appear way too young to explain by social conditioning. Furthermore, by the time they hit kindergarten, boys will play exclusively with each other and form dominance hierarchies based on who is the most athletic. Girls' games, like patty-cake and jump rope, tend to be more cooperative.
Brizendine sees these boy-girl differences in children she has known personally and attributes them to a "pivotal brain difference between males and females." She further states that "during the teen years the flood of estrogen in girls' brains will activate oxytocin and sex-specific female brain circuits, especially those for talking, flirting and socializing." No one can deny that boys and girls are different. But, where is her evidence? Where are the MRIs? Brizendine even goes so far as to graph her observations, like talking, on the same graph with estrogen surges. She is implying that estrogen increases talking at certain times of the month. Does she have replicated studies where girls are given estrogen and specific brain centers are stimulated on MRIs and increased talking is measured and documented?
I followed up Brizendine's citations and unfortunately the research she cites is weak. The few research studies she refers to are generally conducted on rats or mice. The one she relies on most heavily is conducted on a small sample of teens and is not replicated and studies cortisol, not estrogen or oxytocin. Saying things like teenage girls brains are "marinated" in hormones and this explains their need to bond with girls and talk, talk, talk, causes her book to look unscientific and lose credibility. Furthermore, gender differences have been studied by developmental and social psychologists with rigorous scientific methodology for decades. How can she ignore this body of scientific data?
In sum, Brizendine's book is neither new nor accurate. In 1969, my UCSD professor showed our freshman biology class the same graph of estrogen and progesterone cycles. That women have monthly hormonal cycles which start in adolescence is not new. But to say that intimacy and talking are caused by brains "marinated" in estrogen is unscientific and unconscionable by an MD affiliated with a prestigious medical center.
Brizendine oversimplifies a complex process and ignores rigorous experiments of gender differences from social, developmental, and experimental psych. Instead of basing her conclusions on scientific studies of gender differences, she observes friends and clinical cases and assumes their behavior is motivated by biology. Both her logic and evidence are weak.
The book, The Female Brain, is a light and entertaining read, but it is more Starbuck's Oprah and opinion than serious science.
