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 itâ€™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.
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.