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  • Human and animal studies indicate that adoptive parents and fathers...

    Human and animal studies indicate that adoptive parents and fathers also reap brain benefits from taking care of offspring.

  • “I’d really love to believe ... that motherhood is making...

    “I’d really love to believe ... that motherhood is making me smarter and that at least my brain is getting a good workout in every day,” says Jodi Torres, a mother of two from Coto de Caza. Studies have indicated that this might be true.

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When Jodi Torres of Coto de Caza reflects back on the person she was 11 years ago, before she became a mother, she sees a completely different person. “My life was simple. I focused on my husband, my job and I traveled a lot,” said Torres, who worked as a pharmaceutical sales rep.

When she became pregnant with her second child, Torres quit her job and became a full-time mom. “With two kids, life has become really busy and really complicated,” she said.

Indeed, kids have changed everything: what Torres thinks about, what she does, what she wears and what she spends money on.

Veteran parents often warn the uninitiated that “kids change everything,” and the well-worn phrase is used in advertisements, parenting books and more. What most people don’t realize is that a woman is chemically changed by pregnancy, childbirth, lactation and parenting.

Researchers say that similar to early brain development in children, the maternal brain may represent a developmental milestone in a woman’s life. They also say that mothers’ brains, hormones and behavior potentially change to the point that it’s not surprising they become versions of their former selves. That change, however, isn’t bad.

Understanding mommy brain

“It’s common to hear this erroneous idea that the ‘mommy brain’ is something that’s negative,” said Kelly Lambert, Ph.D, a leading researcher on the maternal brain and a professor of psychology at Randolph-Macon College in Virginia. During pregnancy, a woman’s brain volume decreases slightly as a way for the body to conserve resources for the growing fetus. This can negatively influence memory, for example. “But this negative version of mommy brain is only temporary. What women don’t commonly understand is that there are some fairly substantial long-term brain development benefits to becoming a mother.”

The real mommy brain, Lambert said, belongs to a woman who is smarter, braver and better able to handle stress.

Maternal brain research

Though it hasn’t gotten widespread popular attention, maternal brain research – often done on lab rats and sometimes humans – has steadily been piling up since the mid-1980s, when Robert Bridges, Ph.D, now at Tufts Cummings School of Veterinary Medicine, reported that the production of estrogen and progesterone increased at certain points during pregnancy and that maternal behavior depended on this interplay of hormones and their eventual decrease.

Michael Numan, Ph.D., formerly of Boston College, added to the research by demonstrating that a part of the female brain’s hypothalamus, the medial preoptic area (mPOA), is largely responsible for maternal activity. After giving birth, the mPOA neurons direct the mother’s attention and motivation to her offspring, enabling her to care for, protect and nurture her kids with a collection of behaviors we call maternal. Studies like these were important because they established that maternal behavior is driven not only by social expectations, but by real brain adjustments in the new mother.

Gray matter increases

More recent work, such as a study published in 2010 in the journal Behavioral Neuroscience, posits that hormonal changes in the mother starting right after birth, including increases in estrogen, oxytocin and prolactin, literally reshape the maternal brain with long-term consequences.

Researchers in the Behavioral Neuroscience study performed baseline and follow-up high-resolution magnetic-resonance imaging on the brains of a small group of women who gave birth at Yale-New Haven Hospital. A comparison of images taken two to four weeks and three to four months after the women gave birth showed that gray matter volume increased a small but significant amount in various parts of the brain – something that only happens when, for example, significant learning is taking place. The increased brain areas corresponded with motivation (hypothalamus), reward and emotion processing (substantia nigra and amygdala), sensory integration (parietal lobe), and reasoning and judgment (prefrontal cortex).

And, research in Lambert’s lab, in collaboration with the lab of the late Craig Kinsley of the University of Richmond, looked at foraging behavior in nonmom rats vs. mother rats. “What we found is that females with maternal experience are actually more efficient at finding food; they seem to learn and remember quicker and they make fewer errors,” Lambert said.

Faster foragers

Additional research at the University of Richmond has also indicated that mother rats are faster than nonmothers at capturing prey. Slightly food-deprived mother and nonmother rats were each placed in a 5-square-foot enclosure with wood chips in which a cricket was hidden. The nonmother rats took an average of nearly 270 seconds to find the cricket and eat it, compared with just more than 50 seconds for the mother rats. Even when the experiment was manipulated so that the nonmothers were made hungrier than the mothers or when the sounds of the crickets were muffled, the mothers were still able to find the crickets more quickly.

Lambert says her research has demonstrated that mother rats nearly always beat nonmother rats in competitions that involve simultaneously monitoring sights, sounds, odors and other animals. Having more than one pregnancy seems to give a mother rat an even greater edge. One study looked at a race to find Fruit Loops cereal (a preferred food for rats). Rats who had two or more pregnancies were the first to nab the treats 60 percent of the time. Rats who had given birth just once captured the Fruit Loops 33 percent of the time, and nonmother rats got them only 7 percent of the time.

Improved memory

Other research has found that mother rats who are least 2 years old – equal to human females older than 60 – are much faster at spatial tests than age-matched nonmother rats and exhibit less steep memory declines.

At every age tested, the mother rats outshone their virgin sisters at remembering the locations of food rewards in mazes. When researchers looked at the brains of the mother rats after the testing, they also discovered fewer deposits of amyloid precursor proteins – which appear to play a role in the degeneration of the aging nervous system – in key parts of the brain of mom rats vs. nonmom rats.

“From everything we know now, we believe that the hormones of pregnancy, along with the enriching sensory environment of having to take care of offspring, might mitigate some of the effects of aging on cognition,” Lambert said.

Bolder mother rats

Other animal research has indicated that motherhood may make mothers less fearful and bolder. In one study, mom rats and nonmom rats were allowed on a raised maze with enclosed and open spaces. The mom rats spent far more time on the open sections of the maze vs. their nonmom counterparts, leading researchers to conclude that the mothers demonstrated bolder and less fearful tendencies.

The bigger picture

“All of the research on the maternal brain is interesting work and it’s also a natural extension of a huge movement right now overtaking not just neuroscience, but all medicine,” said Larry Cahill, Ph.D, professor of neurobiology and behavior at UC Irvine. “The differences between males and females has long been underappreciated and understudied to the detriment of women’s health.” Cahill contends we’re in the midst of a large cultural change that is finally taking women’s health and even motherhood more seriously. “There is a real zeitgeist shift happening throughout medicine.”

Research that indicates the female brain changes with pregnancy and parenting, Cahill says, could some day have important implications on medication side effects, dosing or even new discoveries on how to treat depression, anxiety and other mental health issues in many women.

“The bigger message here is that more and more research proves that women aren’t just men with testy hormones. Healthwise, there’s a lot more we need to know about being female and being a mother.”

Lambert says research on the maternal brain may have a variety of societal implications. For example, when researchers in her lab simulated poverty conditions for pregnant rats – for example, by not giving them enough bedding or paper towels to nest properly once they delivered – they found that the mother rats didn’t respond in the predicted maternal fashion. Instead, they became confused and overwhelmed. Of course, research like this could be important for social policy and mental health work.

Brain exercise

“What we know right now, though, is that being a mother under most circumstances is comparable to good exercise for the brain,” Lambert said. “And it’s exercise that could serve women well throughout their lives. We need more human research, but I can imagine that the flexibility required with being a mother, as well as the social attentiveness and the organization needed to raise children, might prove to make someone a better manager, a better executive, or just someone who is better able to get a lot of things done. It would be great if more people in our society recognized these benefits.”

Torres said that between ferrying her kids to school, heading up the elementary school yearbook, helping with fundraisers and dealing with sports games, practices, homework, doctor appointments, play dates and piano lessons, she’ll have to give mommy brain some more thought.

“I know that my body has changed due to motherhood, I know that my schedule has changed and my priorities have changed, but this is the first time I’ve ever heard that my brain may have changed for the better. I’d really love to believe, though, that motherhood is making me smarter and that at least my brain is getting a good workout in every day.”