The Female Brain (8 page)

A teenage boy feels alone in and ashamed by his thoughts. Until his buddies start to joke and comment about girls’ bodies, he thinks he is the only one consumed by such intense sexual fantasies and the constant fear that someone will notice the erections over which he seems to have no control. Compelling masturbatory frenzies overwhelm him many times a day. He lives in fear of being “found out.” He’s even more wary of verbal intimacy with girls, though he dreams of other kinds of intimacy with them day in and day out. For a few of the teen years, the teen girl brain and the teen boy brain have seriously different priorities when it comes to being close.

F
EAR OF
C
ONFLICT

Studies indicate that girls are motivated—on a molecular and a neurological level—to ease and even prevent social conflict. Maintaining the relationship at all costs is the female brain’s goal. This may be especially true in the teenage female brain.

I remember when my friend Shelley’s oldest teenage daughter, Elana, had sleepovers nearly every night with her best friend, Phyllis—and on the nights they didn’t, they talked on the phone until they had to go to sleep. They planned their outfits, talked about crushes on boys, and watched TV together over the phone. One day Phyllis started bad-mouthing a less popular girl in class, who had been close friends with Elana in grade school. Her meanness made Elana uncomfortable and angry, but as she thought about confronting Phyllis, her mind and body were seared by a wave of anxiety. It became real to her that if she made even a hint of criticism to Phyllis’s face, a fight that would spell the end of the friendship could result. Instead of risking the loss of her friendship with Phyllis, Elana decided to say nothing.

This is a tape that plays in the brain of every woman at the thought of conflict, even a small disagreement. The female brain has a far more negative alert reaction to relationship conflict and rejection than does the male brain. Men often enjoy interpersonal conflict and competition; they even get a positive boost from it. In women, conflict is more likely to set in motion a cascade of negative chemical reactions, creating feelings of stress, upset, and fear. Just the thought that there might be a conflict will be read by the female brain as threatening the relationship, and bring with it the real concern that the next conversation she has with her friend will be their last.

When a relationship is threatened or lost, the bottom drops out of the level of some of the female brain’s neurochemicals—such as serotonin, dopamine, and oxytocin (the bonding hormone)—and the stress hormone cortisol takes over. A woman starts feeling anxious, bereft, and fearful of being rejected and left alone. Soon she begins to jones for that good intimacy drug, oxytocin. She gets a feeling of closeness from the flood of oxytocin, which is boosted by social contact. But the minute that social contact is gone and the oxytocin and dopamine bottom out, she’s in emotional trouble.

As soon as a woman gets her feelings hurt, the hormonal shift sets off a fearful fantasy that the relationship will be over. This is why Elana decided to let Phyllis’s mean comment about her old friend go so she didn’t have to risk the fight that might end the friendship. That’s the fearful reality playing out in the female brain. This is why the breakup of a friendship, or just the thought of social isolation, is so stressful, especially among girl teens. Many brain circuits are geared to monitor closeness, and when closeness is threatened, the brain sounds the abandonment alarm loudly. Robert Josephs at the University of Texas has concluded that men’s self-esteem derives more from their ability to maintain independence from others, while women’s self-esteem is maintained, in part, by the ability to sustain intimate relationships with others. As a result, perhaps the greatest source of stress in the woman’s or girl’s brain can be the fear of losing intimate relationships and the lack of vital social support that might ensue.

A girl’s increasing stress and anxiety response at puberty may even be related to the formation of cliques and clubs. In fact, the formation of cliques may be the result of her stress response. Until recently, it was assumed that all human beings reacted to stress with the “fight or flight” response, a behavior described by W. B. Cannon in 1932. A person under stress or threat, the theory goes, will attack the source of that threat if there’s any reasonable chance of winning; otherwise, an individual will flee from a threatening situation. “Fight or flight” behavior, however, may not be characteristic of all humans. The UCLA psychology professor Shelley Taylor argues, in fact, that this is more likely to be the
male
response to threat and stress.

Both sexes, to be sure, experience a powerful flood of neurochemicals and hormones when they come under acute stress, preparing them to meet the demands of an imminent threat. And that cascade can make males spring into action—their aggression pathways are more direct than females’. But fighting may not have been as evolutionarily adaptive for females as it was for males because females have less chance of physically defeating the larger males, and even if they are matched in strength with their opponents, turning to fight could mean leaving a helpless child alone and vulnerable. In the female brain, the circuit for aggression is more closely linked to cognitive, emotional, and verbal functions than is the male aggression pathway, which is more connected to brain areas for physical action.

As for flight, females are generally less able to run when they’re pregnant, nursing, or caring for a vulnerable child. Research has found that female mammals under stress rarely abandon their infants once they’ve formed maternal bonds. As a result, females appear to have some stress responses in addition to “fight or flight” that allow them to protect themselves and their dependent children. One such response may be reliance on social ties. Females in a bonded social group are more likely to come to one another’s aid in a threatening or stressful situation. Members of a group can alert one another to conflict ahead of time, enabling them to move away from potential danger and continue safely tending dependent children. This pattern of behavior is termed “tend and befriend,” and it may be a particularly female strategy. Tending involves nurturant activities that promote safety and reduce distress for the self and offspring; befriending is the creation and maintenance of social networks that may aid in this process.

Remember, our modern female brain still has the ancient circuitry of our most successful foremothers. Early in mammalian evolution, females may well have formed social networks for support when threatened by males, as studies of some nonhuman primates indicate. In certain species of monkeys, for example, if a male is overly aggressive to a female, the other females in her group will come and face the male down, standing shoulder to shoulder, chasing him away with threatening cries. These female networks provide other types of protection and support, too. Many species of female primates will watch and care for one another’s infants, share information about where to find food, and model maternal behavior for younger females. The UCLA anthropologist Joan Silk found a direct link between the degree of social connectedness of female baboons and their reproductive success. Her sixteen-year study showed that mothers who were the most socially connected had the greatest number of surviving infants, increasing their success at passing on their genes.

Teen girls begin automatically building and practicing these friendship connections during their intimate talks in the school’s bathrooms. Biologically, they are reaching optimal fertility. The Stone Age brains within them are flooded with neurochemicals telling them to connect with other women so that they can help protect the young. The primitive brain is saying, “Lose that bond, and both you and your offspring are toast.” That’s a powerful message. No wonder girls find it unbearably hard to cope with feelings of being left out.

T
HE
B
RAIN
M
ARCHES TO THE
B
EAT OF
E
STROGEN’S
D
RUM

By the time Shana was ten years old, it was harder for Lauren to wake her up for school. Shana started sleeping until noon on weekends. Lauren was sure this sleep pattern reflected Shana’s bad habits—she waited until the last minute to finish big projects, and she liked to stay up watching television. Shana was beginning to feel depressed because her mom was calling her a lazy bum all the time, but Shana couldn’t see why. She was tired and wanted to sleep. Mother and daughter were locked in battle when I first saw them.

In reality, the sleep cells in Shana’s brain had been reset at puberty by her ovarian estrogen surges. Estrogen affects practically everything that a teen girl experiences, including responsivity to light and the daily light-dark cycle. Estrogen receptors get activated in the brain’s twenty-four-hour clock cells in the suprachiasmatic nucleus. These clusters of cells orchestrate the daily, monthly, and annual rhythms of the body, such as those of hormones, body temperature, sleep, and mood. Estrogen even directly influences the brain cells that control breathing. It turns on the uniquely female sleep cycle as well as her growth hormone. By puberty, estrogen sets the timing of everything in the female brain—the female and male brains end up marching to different drummers.

At around age eight to ten for girls—and a year or more later for boys—the brain’s sleep clock begins to change its settings, leading to later bedtimes, later wake-up times, and more sleeping time overall. One study showed that at age nine boys’ and girls’ brains had exactly the same brain waves during sleep. By age twelve girls had a 37 percent shift in their brain waves during sleep compared to boys. The scientists concluded that this indicated that girls’ brains mature faster. The pruning of excess synapses in teen girls’ brains starts earlier than it does in boys, thus moving them more quickly toward maturation of all their brain circuits. The female brain, on average, matures two to three years earlier than the male brain. A similar condition develops in boys’ brains a few years later, but their sleep phase is pushed even an hour later than girls’ by the age of fourteen. And this is just the beginning of being out of sync with the opposite sex. Females’ tendency to go to sleep and wake up a bit earlier than do males is a difference that will last until after menopause.

I saw Shana and her mother many times over the years. Things became even rockier as Shana got several years into the new rhythm that estrogen was establishing in her brain. It was day twenty-six of her cycle, and Shana wasn’t just screaming. She was shrieking. “I am going to the beach tomorrow and there’s nothing you can do about it. Just try to stop me.”

“No, Shana,” Lauren responded, “you’re not going with that group of kids. I told you I don’t like the fact that they throw around so much money, and I’m pretty sure they’re into drugs.”

“You don’t know what you’re talking about. You’re a stupid old prude who just doesn’t have a life. You never had one. You were ugly and boring and a goody-two-shoes kid. You wouldn’t know cool if it smacked you in the face. You can’t stand it that I’m smarter than you and cooler than you, and you just want to keep me down. You’re a fucking asshole!”

Lauren lost it. For the first time in her life, she slapped her daughter.

The most obvious cycle controlled by estrogen is the menstrual cycle. The first day a young girl gets her period can be exciting and bewildering. It is a moment to celebrate, not in a New Age, hippie sense but because each month the menstrual cycle refreshes and recharges certain parts of a girl’s brain. Estrogen acts as a fertilizer on cells—exciting her brain as well as making a girl more socially relaxed during the first two weeks. There’s a 25 percent growth of connections in the hippocampus during weeks one and two (the estrogen phase), and that makes the brain a little bit sharper. It functions a little better. You’re clearer and you remember more. You think more quickly and more agilely. Then at ovulation, around day fourteen, progesterone starts squirting out of the ovaries and reversing the actions of estrogen, acting more like weed killer on those new connections in the hippocampus. During the last two weeks of the cycle, progesterone causes the brain to become first more sedated and gradually more irritable, less focused, and then a little slower. This may be one of the pivotal reasons for the change in stress sensitivity during the second half of the menstrual cycle. The extra connections built during the weeks that estrogen is on the rise are being reversed by progesterone in the last two weeks.

In the last few days of the menstrual cycle, when progesterone collapses, this calming effect is abruptly withdrawn, leaving the brain momentarily upset, stressed, and irritable. This is where Shana was when she screamed at her mother. Many women say they cry more easily and often feel out of sorts, stressed, aggressive, negative, hostile, or even hopeless and depressed right before their periods begin. In my clinic we call them the “crying over dog food commercials” days, because even silly, sentimental things can trigger a tearful response during this short time. At first this abrupt mood change takes girls like Shana by surprise. Teens think that all they need to know about the menstrual cycle is to remember their Tampax and take Advil or Aleve for the cramps on the day the blood flow starts. The idea that even when they’re not bleeding there could be brain effects from their cycling hormones takes some getting used to. By adulthood, they know how to handle it. Most women know that, in weeks three and four, angry impulses fall under the two-day rule. They’ll wait two days and see if they still want to act on them.

It took another few days for Shana to realize she should not have spoken to her mother the way she did. And as her progesterone cycled out and her estrogen came back up, her irritability began to wane. Connections were once again sprouting in the hippocampus, and her brain gears were greased and working to full capacity. Pretty soon she was surprising everyone with her wisecracks and smart-alecky remarks, and they were getting her into a bit of trouble—the boys just couldn’t keep up at times, and she was riding the edge with the girls. Brain performance in some females can fluctuate with the hormonal changes of the menstrual cycle. One of the most estrogen-sensitive parts of the brain—the hippocampus—is a major relay station for processing memories for words. This may be one biological reason behind women’s increased verbal performance during the highest estrogen week—week two—of their cycles. I often joke with my female grad students that they should take their oral exams on day twelve of their cycles, which is the peak of their verbal performance. Maybe the same should go for teen girls and the SATs—or for wives wanting to win a fight with their husbands.