Pregnancy Does Not Diminish Brainpower

 

Australian researchers have published evidence that so-called “baby brain” does not exist. Professor Helen Christensen and colleagues at the Australian National University examined the theory.
They recruited 1,241 women aged 20 to 24 years, and tested their cognitive speed, working memory, and immediate and delayed recall. The women were retested after four years and again after eight years. At followups, 76 women were pregnant. A further 188 became pregnant between testing sessions.

No significant differences were seen in their cognitive abilities. The experts believe that neither pregnancy nor motherhood have a detrimental effect on women’s cognitive capacity.
Professor Christensen said, “Part of the problem is that pregnancy manuals tell women they are likely to experience memory and concentration problems, so women and their partners are primed to attribute any memory lapse to the pregnancy.
“Pregnant women may also shift their focus away from work issues to help them prepare for the birth of their new baby, while new mothers selectively attend to their baby. However, this shift in attentional focus is adaptive, and certainly cannot be labeled a ‘cognitive deficit.'”
Details of the study are published in the British Journal of Psychiatry. The team writes, “Not so long ago, pregnancy was ‘confinement’ and motherhood meant the end of career aspirations. Our results challenge the view that mothers are anything other than the intellectual peers of their contemporaries.
“Women and their partners need to be less automatic in their willingness to attribute common memory lapses to a growing or new baby.”
The authors also call on doctors and midwives to put an end to this belief. However, the results of this study directly contradict previous findings which have shown that pregnant women perform worse than nonpregnant women on memory and other cognitive tests. Professor Christensen suggests that the earlier studies were biased because the participants were not tested prior to pregnancy.

“We already tested their cognitive function before they became either pregnant or mothers,” she pointed out. “This is critical as it is the first time that pre-pregnancy cognitive scores were available. We could thus see if pregnancy or motherhood produced any greater change in cognition compared to the controls. Our study used a representative population sample too, rather than a convenience sample.”
A recent study of rats found that pregnancy, motherhood and caring for offspring led to brain changes that suggested “greater resilience to stress, decreased anxiety, and better memory abilities.” The researchers believe the findings could hold true in humans. They say, “It appears that reproductive experience may confer some beneficial changes to human mothers in terms of lowering the anxiety/stress response and enhancing certain aspects of memory.”
Nevertheless, these recent findings contradict the majority of earlier studies. Dr. Julie Henry of the University of New South Wales, Australia, analyzed 14 studies comparing pregnant women with comparable nonpregnant women on memory.
Dr. Henry writes, “Although until recently much of the evidence for pregnancy-related deficits in memory was anecdotal or based on self-report, a number of studies have now been conducted that have tested whether these subjective appraisals of memory difficulties reflect objective impairment.”
She found that the studies “failed to yield consistent results,” but that pregnant women “are significantly impaired on some, but not all, measures of memory, and, specifically, memory measures that place relatively high demands on executive cognitive control.” There is a need to understand the causes of such pregnancy-related memory difficulties, she concludes.
There seems to be a wide gulf between pregnant women’s own self-reports and studies that use objective measures. About two thirds of women report having some kind of memory or attention problems due to their pregnancy. But objective tests are inconsistent.
Dr. Ros Crawley of the University of Sunderland, UK, believes, “Some of the inconsistency in objective tests might be methodological. There’s a lot of different tasks used to measure the same cognitive functions and when people talk about the tasks that they use, sometimes one paper uses it to measure one thing and another paper uses it to measure another, so it’s quite complicated.”
Dr. Crawley’s findings have convinced her that pregnancy is not associated with cognitive decline. “It’s absolutely time we exploded this myth,” she says.
References
Christensen, H., Leach, L. S. and Mackinnon, A. Cognition in pregnancy and motherhood: prospective cohort study. British Journal of Psychiatry, Vol. 196, February 2010, pp. 126-32.
Macbeth, A. H. and Luine, V. N. Changes in anxiety and cognition due to reproductive experience: a review of data from rodent and human mothers. Neuroscience and Biobehavioural Reviews, Vol. 34, March 2010, pp. 452-67.
Henry, J. D. and Rendell, P. G. A review of the impact of pregnancy on memory function. Journal of Clinical and Experimental Neuropsychology, Vol. 29, November 2007, pp. 793-803.

Pregnancy causes many hormonal changes, with some research suggesting it may even impact some of the brain's functions. A new study suggests there may be cognitive advantages to having a pregnancy later in life.

Having a pregnancy later in life may improve cognition in older age.

Pregnancy normally increases the levels of some hormones in the mother's body, such as estrogen, progesterone, oxytocin, prolactin, cortisol, and some endorphins.
Some studies have linked higher levels of estradiol and cortisol with lower attention and have suggested mothers may have poorer verbal memory during pregnancy.
Negative emotional states have also been reported during pregnancy. In fact, 1 in 9 women experience depression before, during, or after pregnancy, according to the Centers for Disease Control and Prevention (CDC).
However, in the long run, pregnancy hormones may lead to better cognition and memory. A new study investigates the link between age at last pregnancy and a mother's cognitive abilities later in life.

Assessing the link between reproductive history and cognition

Researchers at the University of Southern California examined the association between reproductive history, hormonal exposure, and cognition in postmenopausal women.
Factors that influence hormonal exposure and that were considered by the study included reproductive period, pregnancy, and use of hormonal contraceptives.
The analysis evaluated a total of 830 women, using data from two clinical trials.
The average age of the participants was 60 years. The researchers made the necessary adjustments for age, race and ethnicity, income, and education.
Participants were evaluated using a variety of cognitive tests and a reproductive history questionnaire. Researchers tested participants' verbal memory by asking them to remember a list of words or to retell a story after being distracted.
They also assessed their psychomotor speed, attention span, and concentration, as well as their planning abilities, visual perception, and episodic memory.
The findings have been published in the Journal of the American Geriatrics Society.

Pregnancy after 35 linked to better cognition

The study revealed several associations, some of which have been supported by previous research, while others were more surprising.
The study found that postmenopausal women who had their last pregnancy after the age of 35 had better verbal memory.
Those who had their first pregnancy when they were 24 or older had significantly better executive function. This includes attention control, working memory, reasoning, and problem solving.
The study also revealed that having the first menstrual cycle at an early age, along with a longer reproductive life, also led to better executive function in later life.
Estrogen has been shown in previous studies to impact positively on the brain's chemistry, function, and structure in animal studies, explains lead author Roksana Karim, assistant professor of clinical preventive medicine at University of Southern California's Keck School of Medicine. Progesterone has been associated with brain growth and development of brain tissue, she adds.

"Starting your period early means you have higher levels of the female sex hormone being produced by the ovaries. Girls are receiving the optimal levels early, so it's possible that their brain structures are better developed compared to those who are exposed to estrogen levels associated with menstrual cycles at a later age."

Roksana Karim

Researchers also found that women who had used contraceptives for 10 years or more had better verbal memory and critical thinking skills.
"Oral contraceptives maintain and sustain a stable level of sex hormones in our bloodstream," Karim says. "Stable is good."
One result that surprised the researchers was the positive effect an incomplete pregnancy seemed to have on cognitive function.
Women who did not carry their pregnancy to term had better cognition, verbal memory, and executive function, compared with women who had only one full-term pregnancy.
"The finding that even incomplete pregnancies are beneficial was novel and surprising," says senior author Wendy Mack, professor of preventive medicine at the Keck School of Medicine.
Parity was also found to associate positively with cognition. Women who gave birth to two children had better cognition in older age, compared with mothers of one child.

Results at odds with some previous research

This is the first time a study has investigated the association between age at last pregnancy and cognitive function in older age, Karim says. Having the last baby at a later age can be an indicator of a later surge in pregnancy hormones, the author explains.

"Based on the findings, we would certainly not recommend that women wait until they're 35 to close their family, but the study provides strong evidence that there is a positive association between later age at last pregnancy and late-life cognition."

Roksana Karim

However, previous studies have shown that pregnancy can have a negative effect on brain function. Some researchers have found that pregnant women have worse verbal memory and word-listing learning skills, as well as poorer fluency when compared with women who are not pregnant.
Mack explains that such results may have been influenced by other factors, such as other bodily changes or environmental stressors.
"The issue is the human studies have not followed women for the long term. They just looked at women during pregnancy." she says. "We are not sure if we can expect to detect a positive estrogen effect at that point, as the many bodily changes and psychosocial stressors during pregnancy also can impact women's cognitive and emotional functions."
Overall, the new findings are both "intriguing and are supported by other clinical studies and animal studies," adds Mack.
Read about how giving birth for the first time later in life may increase longevity.

Written by Ana Sandoiu