Did you know that every brain starts out as female? At eight weeks of development, either a testosterone surge kills off cells in the communication center of the brain, and grows more cells in the sex and aggression areas (making it a "male brain,") or a surge of estrogen promotes brain growth in parts handling communication, feelings, emotional memory and anger-suppression (making it a "female brain").
In her book The Female Brain, Dr. Laura Brisendine M.D. explores the relationship between female hormonal fluctuations and the female brain. Dr. Brisendine explains that after girlhood, because of hormone fluctuations that continue until after menopause, the female brain actually changes daily, monthly and over a woman's life time. These fluctuations influence her thoughts, desires, emotions and behavior.
For up to two years after birth, a girl's brain is flooded with massive amounts of estrogen, and at around 24 months, hormones are turned off for a juvenile pause.
As a young woman ages, however, estrogen, progesterone and testosterone gradually increase in a monthly cycle. Believe it or not, the female brain changes a little every day once menstruation begins. (In fact, some parts change up to 25% every month!).
From a biological standpoint, puberty is the time when the female brain is conditioned to focus on becoming sexually desirable and attractive, with a primary focus on relationships and love interests. As she matures into having a "single woman brain," hormones urge her to find a mate and choose a life path compatible with raising a family.
Most of us intuitively know that motherhood changes a woman forever. But did you know that motherhood especially changes a woman's brain?
During pregnancy, birth, and child-rearing, the female brain undergoes radical changes structurally and functionally (many irreversible!). After these changes, the brain's #1 goal becomes ensuring the survival of the species.
The mommy brain transformation starts at conception when a woman's brain gets inundated with neurohormones manufactured by the fetus and placenta. Even the most career-oriented woman's brain circuits are changed during the process of motherhood, radically altering the way she thinks and feels and what she finds important.
This isn't bad news at all; it's part of evolution! After undergoing childbirth, the mother will feel a biological need to maintain close physical contact with her baby, revealing that her mothering behavior is coded deep in her genes. How? The brain, you guessed it!
After childbirth, new neurochemical pathways are formed in a mother's brain to reinforce maternal behavior, new responses, and priorities. Her brain and reality have both been transformed. And because of regular oxytocin rewards, the bonding and caring hormone, even fathers, adoptive parents, and care givers can experience similar differences when in close daily contact with an infant.
These brain changes are an essential part of motherhood, and certainly make the process easier on mom and baby alike. But that doesn't mean they don't also present challenges. In today's society where many women give birth and soon head right back to work, these brain changes can create profound conflict when it comes to what we often talk about as " work life balance."
For about six months, the parts of the mommy brain responsible for focus and concentration are preoccupied with protecting and tracking the baby. This can result in what feels like decreased brain power, and increased stress and anxiety when separated from the child — especially if nursing.
This is natural, plain and simple. During the child-rearing years that follow, oxytocin helps keep a woman focused on tending to and caring for the family and avoiding conflict to keep it together.
After the mommy brain stage, the female brain goes through a second major change, similar to adolescence called perimenopause, which can make a woman as moody as when she was a teenager. Her brain becomes less sensitive to estrogen, and her ovaries make erratic amounts of it before eventually stopping causing the well-known hot flashes and irritability as well as erratic sleep, fatigue, joint pain, decreased sex drive and anxiety.
This leads to menopause (which starts, on average, at 51). Since estrogen also effects the brain's neurotransmitters controlling mood and memory, many perimenopausal women suffer from depression and memory lapses.
But once again, this isn't just a bunch of bad news. Because brain circuits fueled by estrogen, oxytocin, and progesterone become less active, the mommy brain begins to unplug, and a woman's interests start to expand with her focus shifting to herself: staying healthy, improving well-being, and embracing new challenges which can result in positive life changes.
Once estrogen levels drop and the kids leave home, oxytocin also declines and the mature female brain gets a second wind. What had been important to women earlier in their lives (e.g. connection, communication, approval, children, making sure the family stayed together) is no longer their biological priority.
Her brain circuits are now free to entertain new thoughts, ambitions and ideas. Many women may feel sad, lost, and disoriented because the changing chemicals in their brains literally shift their realities — again. After the transition period, the twilight years for many 50+ women are characterized by an increased zest for life and appetite for adventure.
At this stage, the female brain actually becomes more stable with lower steady estrogen and oxytocin which translates into less emotion and more calm with brain circuits less reactive to stress.